Tag Archives: ozone

Ozone pollution is causing billions worth of damage to East Asian crops

In the upper atmosphere, ozone protects us from dangerous ultraviolet radiation but closer to Earth it can harm plants, animals, and even humans. In East Asia, a growing concentration of ground-level ozone is severely affecting air quality and crops, with a cost estimated at $63 billion a year due to lower yields, according to a new study. 

Image credit: Shawn Harquail / Flickr.

Surface ozone is created by the chemical reaction between nitrogen oxides (NOx) and volatile organic compounds (VOCs). This happens when pollutants emitted by power plants, cars, refineries, boilers, and other sources chemically react in the presence of sunlight. Ozone can be transported long distances, so even rural areas can be affected.

Ozone in the air we breathe can affect our health, especially on hot sunny days, when ozone can reach unhealthy levels. Elevated exposure can also affect vegetation and ecosystems. In particular, ozone can harm vegetation during growing season. When it enters a plant, it affects a plant’s ability to carry out photosynthesis (the process to convert sunlight into energy), which can severely affect or outright kill the plant.. 

In a new study, researchers from the Nanjing University of Information Science and Technology in China analyzed the threat of elevated surface ozone levels to crop production in East Asia, especially to wheat in China and rice across China, Japan, and South Korea. They combined air monitoring at 3,000 locations and ozone experiments, quantifying the damage and the cost caused by ozone pollution. 

“Despite the deceleration of the increase or even decrease in America and Europe in the last two decades, surface ozone concentration is increasing in Asia and has outweighed trends in other regions,” the researchers wrote in their paper on Nature. “Surface ozone poses a threat to food security due to its deleterious effects on crop production.”

The ozone challenges

In the study, the researchers found that an average of 33% of China’s wheat crop is lost every year because of ozone pollution, with 28% lost in South Korea and 16% in Japan. For rice, the average figure in China was 23%, though hybrid strains were more vulnerable. In South Korea, the figure was almost 11%, while in Japan it was over 5%.

This is an especially concerning issue for China, as it has to feed 20% of the world’s population with just 7% of the world’s farmland. The country has lost 6% of its arable land (or 7.5 million hectares) from 2009 to 2019, according to government data, a trend that is expected to continue by 2030 due to industry, energy, and urban expansion. 

“The quantification of the ozone impacts is a premise for any planned actions to protect Asian food production from the increasing threat of surface ozone. However, the real challenge would be to reduce the O3 levels, which should be achieved by applying drastic cuts in the emissions from road transportation and the energy sector,” the researchers wrote. 

In the study, they suggest rigorous emission regulation among Asian countries could lead to higher ozone reduction targets. Besides this, ozone-induced crop yield losses could also be reduced by implementing a combination of agronomic practices such as adjustment of water supply and breeding and selecting more ozone-tolerant cultivars and hybrids.

The study was published in the journal Nature.

This year’s ozone hole was “quite large”, says monitoring body

The ozone hole shifts in size with every year and season, but this year, it’s been the largest and deepest seen in recent times, according to scientists at the Copernicus Atmosphere Monitoring Service (CAMS).

Current readings (orange) and estimations for future (red) size of the ozone hole in 2020. Image credits CAMS.

The maximum annual size of the ozone hole above Antarctica was much bigger this year compared to recent years, hot on the heels of an “unusually small and short-lived” one in 2019, CAMS explained. This event highlights that there’s still work to be done on restoring the ozone layer and that we need to better enforce current bans on chemicals such as chlorofluorocarbons (CFCs), which are known to contribute to ozone depletion.

No ozone zone

“There is much variability in how far ozone hole events develop each year. The 2020 ozone hole resembles the one from 2018, which also was a quite large hole, and is definitely in the upper part of the pack of the last fifteen years or so”, said Vincent-Henri Peuch, director of CAMS.

The ozone layer in Earth’s upper atmosphere absorbs most of the incoming ultraviolet radiation (UV) from the sun that would otherwise be damaging to life on our planet.

Human-made chemicals, in particular refrigerant gases in the CFC family, however, have severely damaged this layer in the past. Countries all around the globe had to work together to ban such chemicals and help shield humans and wildlife from the very real danger of ozone depletion.

Despite the Montreal Protocol, which banned the production and use of CFCs, being signed in 1978, the ozone layer has not yet recovered fully. The ozone hole has become an unfortunate mainstay in the Earth’s upper atmosphere, showing yearly and seasonal variations in size. During the Arctic winter (these gases tend to concentrate at the poles), incoming force chlorine and bromine compounds into more reactive ones, which interact with ozone, depleting the layer.

CAMS explained that this year’s large rip in the layer was generated by a “strong, stable and cold polar vortex”. The polar vortex is an area of long-term low air pressures where temperatures can reach almost -80°C (-112°F); this vortex tends to remain centered around the Ross ice shelf area.

“With the sunlight returning to the South Pole in the last weeks, we saw continued ozone depletion over the area,” Peuch explains.

“After the unusually small and short-lived ozone hole in 2019, which was driven by special meteorological conditions, we are registering a rather large one again this year, which confirms that we need to continue enforcing the Montreal Protocol banning emissions of ozone-depleting chemicals.”

Ozone is considered a pollutant at ground level, and it has a pretty unpleasant smell, similar to that of chlorine-based cleaning compounds. It’s a very powerful oxidant (being an unstable molecule with 3 oxygen atoms) and will thus chemically attack living tissues in animals or plants. However, we wouldn’t be alive without it — the ozone layer blocks between 97 and 99 percent of all incoming UV light.

Antarctic ozone hole at its smallest recorded size ever

The ozone hole over the Antarctic registered its smallest annual peak on record (tracking began in 1982) according to an announcement by the National Oceanic and Atmospheric Administration (NOAA) and NASA on Monday.

Image credits NASA Ozone Watch.

Each year, an ozone hole forms during the Southern Hemisphere’s late winter as the solar rays power chemical reactions between the ozone molecules and man-made compounds of chlorine and bromine. Governments around the world are working together to cut down on the ozone-depleting chemicals that created this hole, and it definitely helps.

However, the two agencies warn that we’re still far from solving the problem for good. The small peak in the ozone hole’s surface likely comes from unusually mild temperatures in that layer of the atmosphere seen during this year, they add.

Good but not done

NASA and NOAA explain that the ozone hole consists of an area of heavily-depleted ozone in the upper reaches of the stratosphere. This hole is centered on Antarctica, between 7 and 25 miles (11 and 40 kilometers) above the surface. At its largest recorded size in 2019, the hole extended for 6.3 million square miles (September 8) and then shrank to less than 3.9 million square miles (during the rest of September and October). While that definitely sounds like and is a lot of surface, it’s better than it used to be.

“During years with normal weather conditions, the ozone hole typically grows to a maximum of about 8 million square miles,” the agencies said in a news release.

It’s the third time we’ve seen a similar phenomenon — weather systems slowing down stratospheric ozone loss — take place over in the last 40 years. Below-average spikes in the size of the ozone hole were also recorded in 1988 and 2002.

The stratosphere’s ozone layer helps deflect ultraviolet (UV) radiation incoming from the sun. That’s very good news if you like being alive as UV rays are highly energetic and will cause harm to the DNA of living organisms. UV exposure can lead to skin cancer or cataracts for animals and damages plantlife.

A host of chemicals that used to be employed for refrigeration, including chlorofluorocarbons (CFCs) and hydrofluorocarbons (HFCs), break down ozone molecules in the stratosphere — which exposes the surface to greater quantities of UV. These compounds can last for several decades in the atmosphere and are extremely damaging to ozone during that time, breaking it down in huge quantities.

Humanity bunched together to control the production and release of such chemicals under the Montreal Protocol of 1988, which has drastically reduced CFC emissions worldwide. The ozone layer has been steadily recovering since then, but there’s still a long way to go.

“It’s a rare event that we’re still trying to understand,” Susan Strahan, an atmospheric scientist at the NASA’s Goddard Space Flight Center in Maryland, said in a news release. “If the warming hadn’t happened, we’d likely be looking at a much more typical ozone hole.”

The reactions that break down ozone take place most effectively on the surface of high-flying clouds, but milder-than-average temperatures above Antarctica this year inhibited cloud formation and made them dissipate faster, NASA explains. Since there were fewer clouds to sustain these reactions, a considerable amount of ozone made it unscathed. In a divergence from the norm, NOAA reports that there were no areas above the frozen continent this year that completely lacked ozone.

Warming in the shape of “sudden stratospheric warming” events, were unusually strong this year, NOAA adds. Temperatures in September were 29˚F (16˚C) warmer than usual (at 12 mi/19 km altitude) on average, “which was the warmest in the 40-year historical record for September by a wide margin” according to NASA.

Warmer air weakened the Antarctic polar vortex, a current of high-speed air circling the South Pole that typically keeps the coldest air near or over the pole itself, which slowed significantly (from an average wind speed of 161 mph / 260 kmph to 67 mph / 107 kmph). The slowed-down vortex allowed air to sink lower in the stratosphere, where it warmed and inhibited cloud formation. It’s also likely that it allowed for ozone-rich air from other parts of the Southern Hemisphere to move in.

City building.

Air pollution in large cities can damage your lungs as much as ‘smoking one pack a day’

Air pollution is driving up the number of cases of emphysema, a condition in which destruction of lung tissue leads to wheezing, coughing and shortness of breath.

City building.

Image via Pixabay.

Dirty air just isn’t that good for you. New research led by the University of Washington, Columbia University, and the University at Buffalo comes to report on a new way that air pollution impacts your lungs. The study shows that long-term exposure to all major air pollutants — especially ozone pollution, which is increasing with climate change — is linked with higher incidence of emphysema, a condition in which destruction of lung tissue leads to wheezing, coughing and shortness of breath.

As bad as smoking

“We were surprised to see how strong air pollution’s impact was on the progression of emphysema on lung scans, in the same league as the effects of cigarette smoking, which is by far the best-known cause of emphysema,” said the study’s senior co-author, Dr. Joel Kaufman, UW professor of environmental and occupational health sciences and epidemiology in the School of Public Health.

Living in an area with 3 parts per billion (ppb) higher ambient ozone levels for 10 years is roughly the equivalent of smoking a pack of cigarettes a day for 29 years, the team found, and is associated with the increase in emphysema. They also determined that ozone levels in some major U.S. cities are increasing by 3 ppb due in part to climate change. The annual averages of ozone levels in study areas were between about 10 and 25 ppb.

The findings are based on data from the Multi-Ethnic Study of Atherosclerosis (MESA) Air and Lung studies, an 18-year-long research effort that involved over 7,000 people, detailing the types and levels of air pollution they encountered between 2000 and 2018 in six metropolitan regions across the U.S.: Chicago, Winston-Salem, N.C., Baltimore, Los Angeles, St. Paul, Minnesota, and New York.

The team assessed the levels of air pollution participants encountered by collecting detailed measurements of exposure over several years in the six metropolitan regions. They also took measurements at the homes of many of the participants.

While most of the airborne pollutants are in decline due to successful efforts to reduce them, ozone has been increasing, the team reports. Ground-level ozone is mostly produced when ultraviolet light reacts with pollutants from fossil fuels.

Emphysema levels were measured from over 15,000 CT (computer tomography) scans that identify holes in the small air sacs of the participants’ lungs and lung function tests, which measure the speed and amount of air breathed in and out.

“Rates of chronic lung disease in this country are going up and increasingly it is recognized that this disease occurs in nonsmokers,” said Kaufman, also a professor of internal medicine and a physician at UW School of Medicine.

“We really need to understand what’s causing chronic lung disease, and it appears that air pollution exposures that are common and hard to avoid might be a major contributor.”

The findings are especially important, the team writes, as ground-level ozone levels are rising. The level of emphysema seen on the CT scans “predicts hospitalization from and deaths due to chronic lung disease,” said Dr. R. Graham Barr, professor of medicine and epidemiology at Columbia University who led the MESA Lung study and is a senior author of the paper.

All in all, it’s important that we continue efforts to scrub away air pollution from our homes and cities. At the same time, the authors say we need a better understanding of the ways air pollution impact our lungs, and more research into how we can prevent the diseases it causes.

The paper “Association Between Long-term Exposure to Ambient Air Pollution and Change in Quantitatively Assessed Emphysema and Lung Function” has been published in the journal JAMA.


Climate change and ozone layer holes form feedback loop, reports international panel

The frays in our planet’s ozone layer are leading to changes in the planet’s climate and ecosystem, new research shows.


Image via Pixabay.

Increased solar radiation levels, a consequence of damage to the ozone layer, are causing shifts in the climate which impact the Earth’s natural systems. These changes affect everything from weather to the health and distribution of sea life according to the study’s authors, members of the United Nations Environment Programme’s Environmental Effects Assessment Panel, which informs parties to the Montreal Protocol.

No-ozone zone

“What we’re seeing is that ozone changes have shifted temperature and precipitation patterns in the southern hemisphere, and that’s altering where the algae in the ocean are, which is altering where the fish are, and where the walruses and seals are, so we’re seeing many changes in the food web,” said Kevin Rose, a researcher at Rensselaer Polytechnic Institute who serves on the panel and is a co-author of the review article.

The 1987 Montreal Protocol on Substances that Deplete the Ozone Layer, often shorthanded as the ‘Montreal Protocol’, was the first ever multilateral environmental agreement ratified by all members of the United Nations. Its aim was to protect Earth’s ozone layer (which acts like a kind of planetary sunscreen, blocking UV radiation) by phasing out harmful handmade substances, most notably the chlorofluorocarbons class of refrigerants. All in all, the Protocol was a success, and total mean ozone levels are on track to recover to pre-1980s levels by the middle of this century.

Earlier this year, however, researchers reported detecting new emissions of ozone-depleting substances from East Asia, which could throw a wrench into the plan.

The link between ozone depletion and an increase in UV levels on the Earth’s surface is well known and well documented. However, the effect it has on climate isn’t. In fact, we’ve only recently wisened up to the fact that climate is also affected by ozone depletion. The current paper focuses on the Southern Hemisphere, where a hole in the ozone layer is currently centered around Antarctica.

The increased levels of UV radiation passing through this area have pushed the Antarctic Oscillation — the north-south movement of a wind belt that circles the Southern Hemisphere — further south than it has been in roughly a thousand years, the team reports. This shift is directly fueling climatic changes in the Southern Hemisphere, they add.

In effect, the hole is causing climate zones to shift southward, affecting rainfall patterns, sea-surface temperatures, and ocean currents across large areas of the southern hemisphere. For example, some areas of the oceans have become cooler and more productive, while others have warmed up and lost productivity.

These changes domino into terrestrial and aquatic ecosystems from Australia, New Zealand, Antarctica, South America, Africa, and the Southern Ocean. Warmer oceans are linked to declines in Tasmanian kelp beds and Brazilian coral reefs, and the ecosystems that rely on them. Cooler areas have helped some populations of penguins, seabirds, and seals, who now have more krill and fish to feed on.

Rose also points out to feedback loops linking climate to UV radiation. Higher concentrations of atmospheric CO2, for example, have increased overall ocean acidity. Acid attacks calcium carbonate, the main component of shellfish shells, which renders these animals more vulnerable to UV radiation. Even us, he adds, are likely to wear lighter clothes in the warmer atmosphere we’re creating, making ourselves more susceptible to damaging UV rays. Furthermore, the team found evidence that climate change is also impacting the ozone layer and its recovery.

“Greenhouse gas emissions trap more heat in the lower atmosphere which leads to a cooling of the upper atmosphere. Those colder temperatures in the upper atmosphere are slowing the recovery of the ozone layer,” Rose said.

As one of three scientific panels to support the Montreal Protocol, the Environmental Effects Assessment Panel focused in particular on the effects of UV radiation, climate change, and ozone depletion. Thirty-nine researchers contributed to the article. Rose, an aquatic ecologist, collaborated with the aquatic ecosystems working group, which is one of seven working groups that are part of the panel.

The paper “Ozone depletion, ultraviolet radiation, climate change and prospects for a sustainable future” has been published in the journal Nature Sustainability.

Credit: Max Pixel.

Scientists pinpoint China as major source of banned ozone-depleting chemicals

Credit: Max Pixel.

Credit: Max Pixel.

In the late 1980s, the world was shocked to learn that human activity had created a gaping hole in the ozone layer above Antarctica. What happens next, however, was simply amazing: all UN countries agreed to ban the use of ozone-depleting chlorofluorocarbons (CFCs) under the Montreal Protocol.

Three decades later, the ozone layer has recovered dramatically and scientists expect the hole to completely patch up by 2060. But they also noticed that in recent years the levels of CFCs in the atmosphere weren’t changing as expected. Someone hasn’t been playing by the rules, and according to a new study, this is happening in eastern China.

The smoking gun

At ground level, ozone (or smog) is a poisonous chemical often expelled by vehicle exhaust. High up in the stratosphere, ozone builds up at altitudes between 10 and 50 km where it acts as a shield against the harmful ultraviolet rays, which can cause cancer. Ozone holes occur naturally from cooling, but man-made chemicals — especially those containing chlorine — greatly accelerate their formation. Currently, the ozone hole above Antarctica is the size of North America.

In January 2018, researchers at NASA reported the first direct evidence that the ozone hole is recovering. They studied microwaves emissions that can identify and count trace gases even during the dark southern winter. According to the NASA researchers’ results, the ban on CFCs has resulted in about 20% less during the Antarctic winter compared to 2005. On average, chlorine levels are declining by about 0.8% annually, the authors reported in the Geophysical Research Letters. 

The hole in the ozone layer is getting smaller and smaller. Credit: ECMWF.

Considering the great challenges that had to be overcome to reach this level of global commitment, you can imagine how shocking it must have been to learn that there were signs of a trend reversal. That’s the case at least for CFC-11, one of the banned chemicals under the Montreal Protocol, which was used in refrigeration and the production of foams. Thanks to the global ban, CFC-11 levels have been declining year-to-year. However, in 2012, researchers noticed that the rate of decline of CFC-11 was slowing down which could only mean that someone somewhere was producing or emitting these chemicals which also trap 5,000 times more heat than CO2.

Many suspected China as the epicenter of this new pollution, but there wasn’t any official proof — until now. In an effort to pinpoint the source of the new emissions, researchers at the University of Bristol, Kyungpook National University, and the Massachusetts Institute of Technology looked at air quality data from monitoring stations in Hawaii, Japan, and Korea. Analysis of this data suggested that China accounted for 40% to 60% of the global increase in trichlorofluoromethane, or CFC-11, emissions between 2014 and 2017. These emissions primarily came from the Chinese northeastern provinces of Shandong and Hebei, according to the study published in Nature.

In 2018, the New York Times published a report accusing some Chinese factories of disregarding the Montreal Protocol by employing CFC-11 in the manufacturing of refrigerants and foams because it is cheaper.

“Several considerations suggest that the increase in CFC-11 emissions from eastern mainland China is likely to be the result of new production and use, which is inconsistent with the Montreal Protocol agreement to phase out global chlorofluorocarbon production by 2010,” the scientists wrote in the abstract of the study.

Chinese authorities started to crack down on the illegal production and use of CFC-11 following international pressure. Now, the authors of the new study hope that their findings will help authorities narrow down the sources and locations of pollutions.

Atmospheric readings show someone is producing illegal, ozone-depleting industrial gases

Atmospheric readings show that someone, somewhere, isn’t playing by the rules.


Aerosol used to widely incorporate these dangerous chemicals.
Image credits PiccoloNamek / Wikimedia.

Just last November, I’ve had the pleasure to report that, according to NASA’s measurements, 30 years of international effort and cooperation were doing the ozone layer some good. It was, all in all, very good news: it showed states could successfully and sensibly work together on ecological problems, and it meant we won’t get fried by solar radiation — both wins in my book.

However, a new study shows that not all is as well as we thought: someone has been cheating on the Montreal Protocol by producing new ozone-depleting chemicals on an industrial scale.

The ozone hole, renewed?

The Montreal Protocol of 1987 banned the production of three main ozone-destroying classes of chemicals: chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), and hydrofluorocarbons (HFCs). Since these compounds take an impressively long time to break down in the atmosphere, monitoring systems were set in place to make sure everything went smoothly. And good thing they did.

A team of researchers led by Stephen Montzka of the US National Oceanic and Atmospheric Administration (NOAA) reports that something is off with CFC-11 levels in the atmosphere. This chemical — previously used as a solvent, a refrigerant, as a precursor in styrofoam production, and a propellant in spray cans — is currently banned for production under the protocol. We used to employ a lot of it, however, and there are still sources of this gas leaking into the atmosphere (such as old refrigerators in landfills). However, these secondary sources should gradually decline, then disappear completely. As they do, we should see the decline of CFC-11 levels in the atmosphere accelerate.

But we aren’t. CFC-11 levels dropped some 2.1 ppt (parts-per-trillion) each year between 2002 and 2012. Afterward, however, the decline actually started to slow down: between 2015 and 2017, CFC-11 levels in the atmosphere dropped by only 1.0 ppt per year.

The concentration of CFC-11 in the Northern (red) and Southern (blue) Hemispheres compared to projected decline (gray lines).
Image credits Montzaka et al. (2018), Nature.

First, the team checked whether the change could come from natural processes. Some of these, however, could be ruled out quite easily: the first was whether weather-pattern-induced movements of CFCs in the stratosphere caused the observed variations. Another possible explanation, that a lot of old buildings using CFC-11-based ventilation systems were demolished at the same time, was also ruled out, as it didn’t plausibly fit the data, according to the team.

The team used atmospheric modeling to analyze what effect could lead to the observed rise. The concentration of these gases has always been higher in the (more developed, more industrialized) Northern Hemisphere than in the Southern one. Over the last few years, the team reports, this discrepancy between the two hemispheres has become more pronounced. Other gases haven’t followed the same pattern, the authors add, suggesting that the increase in CFC-11 emissions come from somewhere in the Northern Hemisphere.

Measurements taken at the Mauna Loa observatory in Hawaii also show that CFC-11 isn’t the only anthropic pollutant that’s seeing an uptick roughly since the year 2000. The team’s models showed that natural variability in atmospheric circulation (aka weather patterns) could only explain half of the observed increase — meaning that the only plausible explanation is an increase in emissions.

The team report that the source is most likely somewhere in Eastern Asia. They also estimate that around 6,500 to 13,000 tons of new CFC emissions would fit the observed trend in atmospheric concentrations.

“This is the first time that emissions of one of the three most abundant, long-lived CFCs have increased for a sustained period since production controls took effect in the late 1980s,” the researchers write.

“A delay in ozone recovery […] is anticipated, with an overall importance depending on the trajectory of CFC-11 emissions and concentrations in the future.”

The emissions are a direct violation of the Montreal Protocol. Signatories have taken it upon themselves to monitor CFC production and report it back to the United Nation group which oversees the protocol’s implementation. Against this backdrop, the team was very careful to spell out that they don’t have enough data to point towards a specific nation. They also add that its possible such production is taking place beyond the local government’s back — putting the ball in their court to safeguard the ozone layer.

The paper “An unexpected and persistent increase in global emissions of ozone-depleting CFC-11” has been published in the journal Nature.

NASA finds first direct proof that Ozone hole is recovering following chemical ban

Credit: NASA.

Almost 30 years ago, a UN emergency panel banned the use of chlorofluorocarbons (CFCs) under the Montreal Protocol. Scientists had learned that these chlorine-containing chemicals had triggered the formation of a gaping hole in the ozone layer right above Antartica. Since then, the ozone layer has clearly recovered, marking a great success — one of the few but highly commendable episodes where nearly all the world’s countries chose to set aside their differences and work for the common good of the planet and all life that call it home. Now, NASA scientists report that they have the first direct evidence that the ozone hole above the icy continent is clearly getting plugged.

Susan Strahan and colleagues at NASA’s Goddard Space Flight Center in Greenbelt, Maryland analyzed data from the Microwave Limb Sounder (MLS) aboard the Aura satellite, which has been taking measurements around the globe since 2004. Unlike other satellite instruments that rely on sunlight that bounces off molecules to measure atmospheric trace gases, MLS employs microwaves emissions that can identify and count trace gases even during the dark southern winter. During this season, the stratospheric weather is quieter and temperatures are low and stable.

“During this period, Antarctic temperatures are always very low, so the rate of ozone destruction depends mostly on how much chlorine there is,” Strahan said. “This is when we want to measure ozone loss.”

The hole in the ozone layer is getting smaller and smaller. Credit: ECMWF.

The hole in the ozone layer is getting smaller and smaller. Credit: ECMWF.

At ground level, ozone or smog is a poisonous chemical often expelled by vehicle exhaust. High up in the stratosphere, ozone builds up at altitudes between 10 and 50 km where it acts as a shield against the harmful ultraviolet rays, which can cause cancer. Ozone holes occur naturally from cooling, but man-made chemicals greatly accelerate their formation. Chlorine, in particular, is very harmful since these atoms are extremely reactive with ozone. Currently, the ozone hole above Antarctica is the size of North America, which sounds humongous. However, it’s also the smallest it’s been since 1988, according to NASA.

After CFCs were banned, scientists eventually observed that the ozone layer started recovering. Previously, such research argued that ozone depletion is decreasing based on statistical analyses of changes in the ozone hole’s size. Now, Strahan and colleagues report not only the first direct measurements that prove ozone depletion is decreasing but also that the decrease is caused by fewer CFCs in the atmosphere.

The findings are based on yearly MLS measurements conducted between 2005 and 2016. These readings suggest that the ban on CFCs has resulted in about 20 percent less  during the Antarctic winter than there was in 2005. On average, chlorine levels are declining by about 0.8 percent annually, the authors reported in the Geophysical Research Letters. 

“This is very close to what our model predicts we should see for this amount of chlorine decline,” Strahan said. “This gives us confidence that the decrease in ozone depletion through mid-September shown by MLS data is due to declining levels of chlorine coming from CFCs. But we’re not yet seeing a clear decrease in the size of the ozone hole because that’s controlled mainly by temperature after mid-September, which varies a lot from year to year.”

Complete recovery will take decades, however. What’s more, this recovery is delayed by other ozone-burning chemicals like dichloromethane and 1,2-dichloroethane (heavily used in PVC manufacturing in China). According to scientists, the average date for ozone recovery, now set to 2050, could be delayed by 20-30 years, “depending on future emissions of things like dichloromethane.”

Ozone Hole.

Ozone hole at its slimmest after 30 years of international effort, keeps shrinking

The hole in our planet’s ozone layer is getting patched up. At its peak this year, the hole grew to be two and a half times the size of the US territory, its smallest proportions since 1988 according to NASA.

Ozone Hole.

It’s blue, it’s menacing, it’s a bit tinier than last year! Hurrah for progress!
Image via NASA / Ozone Hole Watch.

Spreading up to 7,6 million square miles (19.69 million km2) at its peak this year on September 11, the hole in our atmosphere’s ozone layer seems to be healing. The hole, currently looming above Antarctica, was 1.3 million square miles (3.36 million km2) smaller than last year, the smallest it’s ever been since 1988, and it keeps shrinking.

Atmospheric sunscreen

Ozone, sometimes called trioxygen, is an allotrope (a particular structural layout) of oxygen. It’s a molecule made up of three oxygen atoms, O3, and is less chemically stable than the regular O2 molecule. Ozone is a pale-blue, toxic and quite smelly gas, but that’s ok since it breaks down into regular oxygen in the lower atmosphere. It’s also a relatively rare gas, generally formed in the upper atmosphere under the action of UV rays and the charges they generate in the lower layers of the stratosphere.

Because chemistry has a sense of humor, that same ozone layer absorbs virtually all (98% to 99%) of incoming, medium-frequency UV radiation. Awesome news if you like being alive or at least not in constant agony from radiation burns, since UV radiation can wreak havoc on organisms living on land. Exposure to higher levels of UV radiation (such as those associated with a thinned ozone layer) significantly raise the risks of developing cataract and skin cancer. Wide-scale exposure to UV levels expected in the absence of the ozone layer would drastically impact whole ecosystems at a time, and would significantly change the shape of life on Earth as we today know it.

Heavy use of ozone-damaging chemicals — in particular, clorofluorocarbons and hydrochlorofluorocarbons (CHCs and HCHCs) used in old-timey fridges and spray cans — burned a gaping hole in this layer in the 70’s and 80’s. These substances break apart in the upper atmosphere, freeing chlorine and bromine to bind with the ozone. The reactions are quicker over Antarctica (where the hole currently looms) as the frozen polar stratospheric clouds offer surfaces upon which heterogeneous chemical reactions take place.

The hole understandably had everyone quite panicked. But it’s starting to show signs of healing up.

NASA researchers believe that the increasing temperatures we’ve seen in later years helped plug the hole, as warmer bodies of air in the stratosphere help limit the rise of damaging chemicals, such as chlorine and bromine, to the ozone layer.

“The Antarctic ozone hole was exceptionally weak this year,” Paul Newman, chief scientist for Earth Sciences at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, said in a statement. “This is what we would expect to see given the weather conditions in the Antarctic stratosphere.”

This effect, however, is like the jiggling of the gas indicator while your car is running — quite tiny, and quite chaotic. The lion’s share of the progress, the draining of the gas from your car’s tank in our metaphor, can be tracked down to the year 1987 when the evidence of ozone degradation grew so worrying authorities implemented the Montreal Protocol on Substances that Deplete the Ozone Layer. Over time, the protocol grew to be an international agreement which drove massive efforts, all throughout the world, to phase out most ozone-depleting chemicals.

Almost like international agreements on threatening environmental issues are a good thing in the long run and probably shouldn’t be abandoned, right?

Paris agreement.

Hint, hint, wink, wink, America.
Seen in April at the March for Science, Washington DC. Image credits Becker1999 / Wikimedia.

The good news marks the 30th anniversary of the ozone hole’s discovery. NASA further reports that the ozone hole was at its widest in the year 2000, at 11.5 million square miles (29.78 million km2) and will likely need a further 50 years to return to its 1980s size.

Overall, very encouraging news, but one that goes to show the huge inertia Earth’s systems have in relation to change. A lesson we should take to heart as we try to grapple climate change.

The ozone layer over Antarctica follows a natural thinning cycle each year, which man-made pollutants exarcerbates. Ozone depletion is usually worse the further from the equator and recently an Ozone hole (as defined by a distinct area of very low ozone levels) has been detected above the North Pole in the arctic. Credit: NASA.

Human activity is destroying the ozone layer — again

The ozone layer over Antarctica follows a natural thinning cycle each year, which man-made pollutants exarcerbates. Ozone depletion is usually worse the further from the equator and recently an Ozone hole (as defined by a distinct area of very low ozone levels) has been detected above the North Pole in the arctic. Credit: NASA.

The ozone layer over Antarctica follows a natural thinning cycle each year, which man-made pollutants exacerbate. Ozone depletion is usually worse the further from the equator and recently an Ozone hole (as defined by a distinct area of very low ozone levels) has been detected above the North Pole in the Arctic. Credit: NASA.

After scientists discovered a huge hole in the ozone layer above the Antarctic in 1987, an emergency UN panel banned the use of chlorofluorocarbons (CFCs) under the Montreal Protocol. CFCs build up in the atmosphere and react with the triple oxygen molecule to break it down. Thirty years later, the ozone hole is widely considered plugged — problem solved. Not so fast, caution scientists at the University of East Anglia in the UK. According to a new study, there are still threats to the delicate cushion in the stratosphere shielding us from harmful UV rays, which are due to harmful substances not regulated by the treaty.

A hole in the ozone (and the Montreal Protocol)

Many of the substances still harming the ozone layer were not included in the Montreal Protocol because their impact on the ozone layer was not considered damaging. Chemicals like dichloromethane, which has applications in paint stripping, agricultural fumigation, and pharmaceutical production, were thought to be “too short-lived to reach the stratosphere in large quantities,” explained David Oram, a research fellow at the UK’s National Centre for Atmospheric Science.

At ground level, ozone or smog is a poisonous chemical often expelled by vehicle exhaust. High up in the stratosphere, ozone builds up at altitudes between 10 and 50 km where it acts as a shield against the harmful ultraviolet rays, which can cause cancer. Ozone holes occur naturally from cooling, but man-made chemicals greatly accelerate their formation. Currently, the ozone hole above Antarctica is the size of North America.

Besides dichloromethane, another highly concentrated chemical identified in the stratosphere includes 1,2-dichloroethane — an ozone-depleting substance used to make PVC, a popular construction material. PVC manufacturing has surged in the last couple of years in China, its main hotspot. What was unexpected, however, was the steep rise in dichloromethane emissions (mainly sourced from China) since this is not only expensive but also toxic. “One would expect that care would be taken not to release [dichloroethane] into the atmosphere,” Oram commented in a public statement. Over the past decade, dichloromethane became approximately 60% more abundant in the atmosphere as compared to the early 2000s.

“Our estimates suggest that China may be responsible for around 50-60% of current global emissions [of dichloromethane], with other Asian countries, including India, likely to be significant emitters as well,” says Oram.

Even though these emissions originate in China and other locations around East Asia, these industrial pollutants can easily leach into the tropics, where the air is more readily lifted into the upper atmosphere. In other words, these chemicals, albeit short-lived, have the time to interact with the ozone layer before breaking down.

“We found that elevated concentrations of these same chemicals were present at altitudes of 12 km over tropical regions, many thousands of kilometres away from their likely source, and in a region where air is known to be transferred into the stratosphere,” says Oram.

Ozone layer recovery could be delayed by as many as 30 years by rising industrial pollutants

Right now, the chemicals in question are not present in quantities significant enough to tear a new hole in the ozone layer but at the current rate of development, that may change. As such, the authors of the new paper published in the journal Atmospheric Chemistry and Physics suggest this gap in the Montreal Protocol should be addressed by banning the chemicals or, at least, limiting their capability to leach into the atmosphere. According to Oram, the average date for ozone recovery, now set to 2050, could be delayed by 20-30 years, “depending on future emissions of things like dichloromethane.”

This is not the first study that identifies ‘very short-lived substances’ (VSLS) — chemicals which break down in less than six months — as ozone depleters. In 2015, a study published in Nature Geoscience found VSLS, dichloromethane included, are increasingly contributing to the depletion of the stratospheric shield.

“In the Antarctic region, where the ozone hole forms each year and where ozone decreases are the most dramatic, we estimate that VSLS account for about 12.5 per cent of the total ozone loss.”

“Globally averaged, the ozone loss due to VSLS in the lower stratosphere could be as much as 25 per cent, though it is much smaller at higher altitude,” Ryan Hossaini of the University of Leeds, UK, and lead author of the study said at the time.


Climate change could add twice as many smog days in the United States

The ozone layer is a protective blanket of triple oxygen atoms that makes up the stratosphere and shelters life on Earth from ultraviolet radiation. A couple decades ago, a huge hole was punctured into the ozone layer above Antarctica which got a lot of people worried. Thankfully, it’s been sealed since thanks to a remarkable international effort that drastically reduced the chemical in the air that were puncturing. At ground level, however, ozone is pretty bad if you inhale it and is one of the main components of smog. As the planet warms, polluted air will react more often with the sun’s ray to form more ozone. A new study suggests that in the United States, residents might experience three to nine more days of unhealthy ozone levels by 2050.


Credit: NASA

Ozone occurs naturally at ground-level in low concentrations. The two major sources of natural ground-level ozone are hydrocarbons, which are released by plants and soil, and small amounts of stratospheric ozone, which occasionally migrate down to the earth’s surface. Neither of these two can release enough ozone for it to be considered a threat to health. That’s where man-made activities come in.

Since 1900, the amount of ozone near the earth’s surface has more than doubled. We make ground-ozone by emitting hydrocarbons and nitrogen oxides from automobiles, gasoline vapors, fossil fuel power plants, refineries and other industries. When these chemicals react with sunlight, particularly ultraviolet rays, ozone — a molecule comprised of three oxygen atoms (O3) — is formed.


Credit: nh.gov

Researchers at the Paulson School of Engineering and Applied Sciences (SEAS) looked at how tropospheric ozone generation will be affected across the United States based on projected temperature increases due to climate change. The team was careful to include ozone suppression into their equations, a phenomenon in which very hot temperatures actually impede ozone formation.

“Ozone production accelerates at high temperatures, and emissions of the natural components of ozone increase. High temperatures are also accompanied by weak winds, causing the atmosphere to stagnate. So the air just cooks and ozone levels can build up,” said Harvard’s Loretta Mickley, who also worked on the study.

Despite ozone suppression, many regions of the United States will experience more ozone and, consequently, more smog. California, already the state with the most air pollution, the Southwest, and the Northeast could all get up to nine extra days a year of ozone past safe levels.

These are mean changes from 2000-2009 to 2050-2059 in ozone episode days due to climate change. Credit: Lu Shen/Harvard University

These are mean changes from 2000-2009 to 2050-2059 in ozone episode days due to climate change. Credit: Lu Shen/Harvard University

“In the coming decades, global climate change will likely cause more heat waves during the summer, which in turn could cause a 70 to 100 percent increase in ozone episodes, depending on the region,” Lu Shen, a graduate student at Harvard’s School of Engineering and Applied Sciences, who led the study, said in a statement.

Ozone pollution is linked to shortness of breath, asthma attacks, increased risk of respiratory infections, heart disease and even infertility.

“This research gives us a much better understanding of how ozone and temperature are related and how that will affect future air quality,” Mickley said. “These results show that we need ambitious emissions controls to offset the potential of more than a week of additional days with unhealthy ozone levels.”

Findings appeared in the journal Geophysical Research Letters. 



Nasa graphic showing the extent of the ozone hole over Antarctica Public domain

Short-lived chemicals that burn a hole in the ozone layer are on the rise

After scientists discovered a huge hole in the ozone layer above the Antarctic, an emergency UN panel banned the use of chlorofluorocarbons (CFCs) in 1987. These build up in the atmosphere, react with the triple oxygen molecule and break it down. Since then, ozone has thankfully replenished, thought it might take decades before it reverts to pre-1980 levels. Progress is slow because there are still some plants through out the world who illegally use CFCs (the stuff that used to go into refrigerants or deodorants), but also because there are other ozone-depleting chemicals out there – some recognized, others new and extremely dangerous.  One class of chemicals that has been allowed in the industry since the Montreal Protocol, despite the danger it posses to ozone, is made up of so-called ‘very short-lived substances’ (VSLS) which breakup in under six months. A new study, however, found that these have dramatically increased over the past couple of years and despite their short reaction times, these could prove to be extremely dangerous.

Short lived, but dangerous

Nasa graphic showing the extent of the ozone hole over Antarctica Public domain

Nasa graphic showing the extent of the ozone hole over Antarctica Public domain

At ground level, ozone or smog is a poisonous chemical often expelled by the exhaust of vehicles. High up in the stratosphere, ozone builds up at altitudes between 10 and 50 where it acts as a shield, filtering harmful ultraviolet rays which can cause cancer. Ozone holes occur naturally because of cooling, but man-made chemicals greatly accelerate their formation. Currently, the ozone hole above Antarctica is the size of North America.

Though CFCs have been banned, there are other chemicals that contribute to the Antarctic ozone hole. Ironically, one chemical called dichloromethane that has been officially deemed as a replacement for CFCs following the Montreal Protocol can found in a report authored by researchers at Leeds University which highlights VLSL  that deplete the stratospheric shield. These chemicals   usually break down in less than six months, but simulations show VSLS account for a significant portion of ozone loss in the stratosphere.

“In the Antarctic region, where the ozone hole forms each year and where ozone decreases are the most dramatic, we estimate that VSLS account for about 12.5 per cent of the total ozone loss.

“Globally averaged, the ozone loss due to VSLS in the lower stratosphere could be as much as 25 per cent, though it is much smaller at higher altitude,” Ryan Hossaini of the University of Leeds (U.K) and lead author of the study,

It’s important to consider than over 90% of VSLS occur from natural processes, like the bromine compounds produced by seaweed and the ocean’s phytoplankton. About 10% are man-made chlorine compounds. At first glace, dichloromethane – one of the most abundant man-made VSLS that we know of – doesn’t seem to be that important. The computer models suggest it reduces the ozone layer by less than one per cent, the researchers note, but  atmospheric concentration of dichloromethane has increased dramatically in recent years. In some places, the concentration has doubled since late 1990s levels, which makes it a genuine concern. The findings appeared in  Nature Geoscience. 

“The increases observed for dichloromethane are striking and unexpected; concentrations had been decreasing slowly in the late 1990s, but since then have increased by about a factor of two at sites throughout the globe,” said study co-author Stephen Montzka of the National Oceanic and Atmospheric Administration.

infographic ozone depletion

A graphic shows how very short-lived substances deplete ozone. (Photo: University of Leeds)

Scientists aren’t exactly sure what’s causing the growth of dichloromethane.

“It could be partly due to the fact that dichloromethane is used in the manufacturing process of some HFCs, the ozone-friendly gases which were developed to replace CFCs,” Hossaini said.

Texas chief toxicologist: No need for smog regulations, just stay indoor

Dr. Michael Honeycutt, the top toxicologist in the state of Texas argued that the Environmental Protection Agency (EPA) shouldn’t tighten smog rules because there would be little to no health benefit.

“Ozone is an outdoor air pollutant because systems such as air conditioning remove it from indoor air,” he argues on a blog post on the TCEQ website. “Since most people spend more than 90 percent of their time indoors, we are rarely exposed to significant levels of ozone.”

I don’t even know where to start – so I’ll try to take it slow. The overwhelming majority of scientists argue that the EPA should tighten ozone restrictions. In 2008, the agency set the current ozone standard at 75 parts per billion (ppb). However, in June this year, the EPA’s Clean Air Scientific Advisory Committee (CASAC) somewhere between 60 and 70 ppb. A judge then ruled that the EPA has to draft a tighter smog rule by December, and the agency is expected to do so. However, Dr. Honeycutt, the head of the toxicology division of the Texas Commission on Environmental Quality (TCEQ) has a different opinion. He has joined Texas Republicans and others nationwide who firmly oppose imposing tighter rules on pollution.

Downtown Houston in October, 2008. The city has severe smog issues and new research suggests that pollution from fracking contributes significantly to the problem.

He offers two main arguments – the first one being that ‘people already spend 90 percent of their time indoor’, so why bother reducing smog levels? Well, I’m not gonna bother and explain why that argument is flawed on so many levels, and instead, I’m gonna discuss the second argument. He claims that the slight increase in premature deaths that could result if ozone standards are lowered — due to the fact that lowering levels of nitrogen oxide can temporarily increase ozone levels because nitrogen also helps dissipate ozone. This is indeed true – or at least this is what the accepted models show; but that doesn’t mean that this is a good argument, because in the long run, lowering smog levels would definitely save lives. Elena Craft, a senior health scientist at the Environmental Defense Fund compared this situation to smokers who quit smoking, and have a higher risk of lung cancer right after quitting smoking.

“That doesn’t mean that you don’t quit smoking,” Craft said. The premature death prediction “does not mean pollution is good for you. It means that you need to double down on the efforts to reduce emissions in the air.”

A recent study suggests that the increasing activity in shale gas and oil drilling in the state of Texas has contributed significantly to an increase in ozone levels.

Cropland bordering rainforest in Iguacu National Park, Argentina, Brazil. Photo: Watson Institute, Brown University

World deforestation surprisingly results in net cooling effect


Photo: Altar Places

In the 1950s rainforests  covered 14% of the earth’s land surface; now they cover a mere 6% and experts estimate that the last remaining rainforests could be consumed in less than 40 years. It’s believed that deforestation accounts for about 20% of global emissions of CO2, because of the a reduced carbon storage capacity. Yet there may be a hidden side to deforestation and how it influences climate, however, that few people see. Writing in Nature Climate Change, Professor Nadine Unger of the Yale School of Forestry & Environmental Studies (F&ES) reports that large-scale forest losses during the last 150 years have reduced global emissions of biogenic volatile organic compounds (BVOCs). These compounds, when combined with other found in the atmosphere, produce pollutants that contribute to global warming. Overall, Unger and her team found that the forests transformed into croplands worldwide triggered a net cooling effect on global temperatures, contrary to popular wisdom.

Turning forests into croplands cools the earth

Cropland bordering rainforest in Iguacu National Park, Argentina, Brazil. Photo: Watson Institute, Brown University

Cropland bordering rainforest in Iguacu National Park, Argentina, Brazil. Photo: Watson Institute, Brown University

Plants and animals emit VOCs and the release of these gaseous compounds affects the chemical and physical properties of the atmosphere. In the presence of NOx, produced by fossil fuel combustion and natural processes, biogenic VOCs react in the atmosphere to form tropospheric ozone, an important pollutant. These reactions may also cause a decrease in the concentrations of the hydroxyl radical (OH) and so lead to the accumulation of methane and other greenhouse gases. A further consequence of these reactions is the formation of secondary organic aerosol particles, a component of PM10 in the atmosphere, which has known adverse effects on human health.

The emissions of VOCs by plants are several orders of magnitude higher than by animals and account for a relevant amount of carbon fixed by photosynthesis, especially under stress conditions. So, these VOCs actually hinder how much carbon trees can soak, but why are these emitted in the first place and at such a large cost of resources? This is still debated, but scientists seem to agree that VOCs act as powerful deterrents against pathogens and herbivores, and also contribute to wound sealing. In the case of flowers, VOCs attract pollinators.

Using sophisticated climate modeling, Unger calculated that a 30-percent decline in BVOC emissions between 1850 and 2000, largely through the conversion of forests to cropland, produced a net global cooling of about 0.1 degrees Celsius. During the same time frame, average global temperatures have risen by 0.6 degrees Celsius, largely because of man-made CO2 emissions. While trees mitigate global warming, on one hand, by capturing and storing carbon, Unger’s model suggests that in the broader picture deforestation produces cooling.

So, carbon is sequestrated by the trees and kept from accumulating in the atmosphere where it traps heat and causes surface temperatures to rise. Meanwhile, the disappearance of dark-colored forests has also helped offset temperature increases through the so-called albedo effect – radiation that bounces off the planet back into space. Dark forests absorb heat, but light colored fields actually reflect heat back into space.

BVOCs when coming in contact with other naturally occurring or man-made substances can produce aerosols – fine, liquid or solid particles that  contribute to global “cooling” since they generally reflect solar radiation back into space. Therefore, the model showed that a 50 percent reduction in forest aerosols has actually spurred greater warming since the pre-industrial era. Yet, the broader picture still resulted in a net cooling effect, since the percentage of the planet covered by cropland has more than doubled, from 14 percent to 37 percent since the mid-XIXth century.

“Land cover changes caused by humans since the industrial and agricultural revolutions have removed natural forests and grasslands and replaced them with croplands,” said Unger, an assistant professor of atmospheric chemistry at F&ES. “And croplands are not strong emitters of these BVOCs — often they don’t emit any BVOCs.”

More sophisticated climate models

It’s rather surprising, in light of these findings, that most climate models do not take into account BVOCs, since these emissions are generally perceived as a “natural” part of the earth system. Clearly, if you change the amount of surface covered by forests, then it doesn’t become a natural process anymore.

“Without doing an earth-system model simulation that includes these factors, we can’t really know the net effect on the global climate. Because changes in these emissions affect both warming and cooling pollutants,” she noted.

Unger is careful to note that her model doesn’t suggest that cutting down more trees will help the planet cool down. Instead, she argues that the findings should spark a greater interest in including BVOCs into climate models. Further  research into the matter is also advised, since BVOCs and their interaction with the atmosphere are yet to be fully understood. A 2011 study by researchers at the same Yale School of Forestry & Environmental Studies found that  “if you cut trees in the boreal region, north of 45° latitude, you have a net cooling effect. You release carbon into the atmosphere by cutting down trees, but you increase the albedo effect, the reflection of sunlight.” But in other parts, deforestation can cause warming. For instance, north of Minnesota the temperature has decreased on average 1.5°F because of deforestation, researchers found, while south of 35° latitude, the level of North Carolina, deforestation has led to increased warming. Also, let’s not forget that deforestation causes soil erosion, floods, desertification and, worst of all, loss of biodiversity – how do these elements fit into the greater picture?

Thus it becomes clear that the effects of deforestation are widely varied and complex – we need to know more before we can make any conclusive comments, but that’s what science is for. To study, to debate, to reach the truth.

Ground ozone pollution in India destroys enough crops to feed 94 million

Smog in India. Ozone, the main component of smog, is a plant-damaging pollutant formed by emissions from vehicles, cooking stoves and other sources. Credit: Mark Danielson/Flickr

Smog in India. Ozone, the main component of smog, is a plant-damaging pollutant formed by emissions from vehicles, cooking stoves and other sources. Credit: Mark Danielson/Flickr

Like most developing nations, India is burning a lot of coal to catch ground. As always the case with compromises such as these, economic growth comes at the expense of the environment. Pollution in Delhi, the capital, has reached levels comparable to Beijing, which is when you know you’ve hit a new low. A new study found high concentrations of surface ozone killed enough crops to feed 94 million people who are living below the poverty line. The total damage during 2005, the year the researchers gathered and analyzed data for their work, is worth over $1 billion.

The study

Surface ozone is formed when nitrogen oxides, carbon monoxide and volatile organic compounds react with sunlight after the chemicals’ release from vehicles, industry, or burning of wood or other plant or animal matter. You can recognize it easily when it’s in high concentrations – it has an acrid smell like the one you sense when you’re around spark producing machinery.

When ozone comes in contact with plants, it attacks them, halting growth and ruining crops. An international team comprised of scientists from India and the US calculated the amount of total crop damage from ozone pollution by comparing emissions estimates from 2005 with data about how much ozone each of the target crops could withstand (wheat, rice, soybean and cotton).

The data they gathered was fed into a model which showed during the growth season crops were exposed to ozone levels more than 40 to 50 parts per billion over most of the country. Plants start to exhibit damage when they are exposed to ozone levels that reach 40 parts per billion or above. At the end, the researchers found that India’s economic loss from ozone’s harm to crops amounted to $1.29 billion in 2005, most of the loss being attributed to rice and wheat damage.


Indian farmers harvest rice, one of India’s major crops. A new study shows that, in 2005, ozone pollution damaged enough crops to feed 94 million people living in poverty in India.
Credit: Gates Foundation/Flickr

In total, 6 million metric tons (6.7 million U.S. tons) of India’s wheat, rice, soybean and cotton crops were destroyed in 2005 as a result of ozone surface pollution or enough to feed 94 million people below the line of poverty. There are about 270 million Indians that live in poverty, according to the study which was published in the journal Geophysical Research Letters, a journal of the American Geophysical Union.

Win some, lose some – how will policymakers in India decide?

The researchers say their findings might help policymakers craft new ozone pollution standards. This idea becomes increasingly important when you factor in that the Indian government wants to introduce a new law that subsidizes grain for two-thirds of the country’s residents. The study, the first of its kind to quantify the effects of ozone pollution on crops in India, suggests that 9.2 percent of the new law’s subsidized cereal requirement are lost.

Reducing ozone generation, especially around the big cities, is no easy task. The number of  vehicles on the road in India has nearly tripled in the past decade, with 130 million vehicles on the road in 2013 compared to 50 million in 2003, according to the International Council on Clean Transportation. Also, there are many coal plants and factories being built. To make things worse, there aren’t any long term measurements of surface ozone in India.

One thing’s for sure, policymakers can not afford to ignore these findings. New bills for clean air that include vehicle emission  and tight industry regulation should be carefully drafted.

The ozone hole (purple and blue) covered much of Antarctica in 2006. Image: CAROLYN GRAMLING

Ozone-depleting chemicals still spewed in atmosphere despite international ban

The ozone hole (purple and blue) covered much of Antarctica in 2006. Image: CAROLYN GRAMLING

The ozone hole (purple and blue) covered much of Antarctica in 2006. Image: CAROLYN GRAMLING

In 1985, scientists first noticed a massive “ozone hole” was seasonally appearing over Antarctica and if left unchecked the environmental consequences could grow to become nothing short of catastrophic. To mitigate this issue, the world’s governments convened and agreed in 1987 to sign the The Montreal Protocol – an international treaty designed to protect the ozone layer by phasing out the production of numerous substances that are responsible for ozone depletion. Today, almost thirty years later, despite in theory at least everybody agreed not to spew anymore ozone-depleting chemicals in the atmosphere, NASA reports significant quantities of carbon tetrachloride (CCl4) continue to be released.

Someone has a leak

CCI4 was widely used as a raw material in many industrial uses, including the production of chlorofluorocarbons (CFCs), and as a solvent. After 2007, the more than 200 signatories of the Montreal Protocol reported no new emissions of CCl4, yet the latest NASA measurements  show an average of 39 kilotons are still emitted every year or about 30 percent of what peak emissions were before the substance was regulated.

“We are not supposed to be seeing this at all. It is now apparent there are either unidentified industrial leakages, large emissions from contaminated sites or unknown CCl4 sources,” said Qing Liang, an atmospheric scientist at NASA’s Goddard Space Flight Centre in Greenbelt, Maryland.

“Is there a physical CCl4 loss process we do not understand or are there emission sources that go unreported or are not identified?” Liang asked.

[ALSO READ] Four newly discovered man-made gases destroy the ozone layer

Is it maybe the case that substance stays longer in the atmosphere than thought? The NASA team used the agency’s 3-D GEOS Chemistry Climate Model and data from global networks of ground-based observations to investigate the issue and found that indeed CCI4 stays in the atmosphere 40 percent longer than previously thought. Even in these conditions, atmospheric concentrations of the compound should have declined at an expected rate of 4 per cent per year. Instead, scientists are seeing a decline rate of only one percent.

Despite ‘the law’, someone could care less.

“If you take a train with 100 tanker cars of carbon tetrachloride derailing once a month, that’s how much is being emitted,” says Paul Newman, an atmospheric chemist at NASA Goddard Space Flight Center in Greenbelt, Maryland. “That’s a lot.” The question is “Where’s this stuff coming from? We really don’t know.”

If there would actually be no ozone-depleting chemicals leaching into the atmosphere, the ozone would recover to 1980 levels by 2050.


NOAA researcher Bryan Johnson (left) and University of Colorado, Boulder, researcher Detlev Helmig (right) prepare a tethered balloon that will collect air samples above Utah’s Uintah Basin. Photo: Chelsea Thompson

Oil and gas fields near rural Utah up to 100 times more polluted than busiest cities

Researchers at the  National Oceanic & Atmospheric Administration have published findings that demonstrate what was speculated for a long time – oil and gas drilling in the vicinity of rural Utah is leaking important quantities of volatile chemicals, particularly high ozone levels, that are much higher than those typically found in busy cities. In fact, the pollution in the Uintah Basin is equivalent to that expelled by 100 million cars, even though the region is home to a scarce populace.

One of the largest oil- and gas-producing regions in the U.S., with more than 10,000 wells in operation, the  Uintah Basin also has one of the largest polluting clouds in the world. Unusually high ozone levels have been in the area, and now researchers have found that the atmosphere is packed with  benzene, a carcinogen, and compounds that are precursors of ozone, suggesting serious leaks are happening.

Over two winter months in 2012 and 2013, they used gas chromatography to measure VOC concentrations in ambient air at a site on the northern edge of the basin’s most extensive gas field. Air samples were taken using tethered baloons at a range of altitudes.  Methane and other hydrocarbon volatile compounds known to be released in oil drilling were targeted. This includes benzene and toluene, which are directly toxic to humans.

NOAA researcher Bryan Johnson (left) and University of Colorado, Boulder, researcher Detlev Helmig (right) prepare a tethered balloon that will collect air samples above Utah’s Uintah Basin. Photo: Chelsea Thompson

NOAA researcher Bryan Johnson (left) and University of Colorado, Boulder, researcher Detlev Helmig (right) prepare a tethered balloon that will collect air samples above Utah’s Uintah Basin. Photo: Chelsea Thompson

Most importantly, ozone levels were measured using an ultraviolet absorption monitor. In the stratosphere, the sheet of ozone is imperious to life’s well being on Earth, blocking harmful ultraviolet rays. At low altitudes, close to the ground, ozone is one of the components of smog and is regarded as a pollutant. In urban centers,   ozone forms after  nitrogen oxide  released by the fum exhaust expelled by cars reacts with light.

Needless to say, light alkane volatile compounds in the rural Utah atmosphere were measured at 10 to 100 times greater in concentration that those found in major U.S. cities. Snow cover drives this buildup: It prevents the ground from heating up, which slows surface air from mixing with colder, clean air from higher in the atmosphere. As a result, a layer of air about 50 to 100 m deep stagnates at the surface, accumulating pollutants. These periods coincided with ozone levels that exceeded EPA air quality standards.

Other popular gas and oil drilling sites are experiencing similar problems,  Wyoming or the Colorado Front Range. As a result, gas and oil operators in Colorado were recently forced to tighten their leaks and  capture 95% of their hydrocarbon emissions, including VOCs. Hopefully, similar regulations may become in place at the other sites.

The findings were reported in the journal Environmental Science & Technology.

Gamma-ray burst illustration. (c) NASA

Gamma-ray bursts might cause mass extinction on Earth

Gamma-ray burst illustration. (c) NASA

Gamma-ray burst illustration. (c) NASA

Most of us tend to believe the Earth is a safe heaven, with little regard to outerwordly consequences. The truth is our planet, although without a doubt a true gem within our galaxy, is susceptible to a slew of events triggered from within or well beyond our solar system. A lot of them are very dangerous to life on Earth, be it a menacing asteroid, a solar flare or even a terrifying gamma-ray burst.

Researchers of Washburn University, in Topeka, Kan. have studied gamma-ray bursts and its potential consequences, and now claim the Earth quite probably has been met by such events during its history, with dramatic consequences on the life harbored within it.

Gamma-ray bursts typically occur  when two stars collide, a process which leads to a giant energy burst into outer space. The gamma-ray bursts have the capability of depleting stratospheric ozone, allowing the most powerful and damaging forms of ultraviolet radiation to reach the Earth’s surface. Researchers are now beginning to connect the timing of these gamma-ray bursts to extinctions on Earth that can be dated through the fossil record.

“We find that a kind of gamma-ray burst — a short gamma-ray burst — is probably more significant than a longer gamma-ray burst,” study researcher Brian Thomas of Washburn University, in Topeka, Kan., said in a statement. “The duration is not as important as the amount of radiation.”

There are two types of gamma-ray bursts:  a longer, brighter burst caused by two collinding stars, as discussed earlier, and a short timed burst. The later caused by the collision of two black holes or neutron stars are even more harmful bursting an outrageous amount of radiation, even though the event only lasts a second.

Such an event, the researchers say, happens about once per 100 million years in any given galaxy. But if one did happen here, the results would be devastating. According to the scientists treating the study, if such an event should occur inside the Milky Way, dire consequences might afflict the Earth. The radiation, after reaching the atmosphere, would caused the depletion of the ozone by  knocking free oxygen and nitrogen atoms so they can recombine into ozone-destroying nitrous oxides. Earth would have been hit by several of these short-hard events over the course of its 4.5-billion-year history, according to the study authors.

The researchers are now looking of evidence of such an event. If a gamma-ray burst would have hit the Earth, the best sign of this would be the discovery of isotope iron-60. Isotopes like these   can reveal the strata of the events, it then becomes a matter of looking for extinction events that correlate and examining which species died and which survived.

“I work with some paleontologists and we try to look for correlations with extinctions, but they are skeptical,” said Thomas. “So if you go and give a talk to paleontologists, they are not quite into it. But to astrophysicists, it seems pretty plausible.”


Venus Express has two solar cell panels per wing comprising alternating rows of standard triple junction solar cells as well as highly reflective mirrors to reduce the operating temperatures. (c) ESA

Ozone layer found on Venus

Venus Express has two solar cell panels per wing comprising alternating rows of standard triple junction solar cells as well as highly reflective mirrors to reduce the operating temperatures. (c) ESA

Venus Express has two solar cell panels per wing comprising alternating rows of standard triple junction solar cells as well as highly reflective mirrors to reduce the operating temperatures. (c) ESA

ESA’s Venus Express spacecraft has found an ozone layer high in the atmosphere of Venus, similar to that surrounding Earth and Mars according to astronomers. Ozone is considered fundumental to providing an environment capable of supporting life, as it absorbs much of the sun’s harmful ultraviolet ray. This recent discovery will provide highly valuable insight as to how life formed on our planet, as well as more refined parameters for scientists’ hunt for extraterestial life.

The study was recently presented at the Joint Meeting of the European Planetary Science Congress and the American Astronomical Society’s Division for Planetary Sciences. Franck Montmessin from the Laboratoire Atmospheres, Milieux, Observations Spatiales (LATMOS) in Guyancourt, France, led the team who carried out this study.

“This detection gives us an important constraint on understanding the chemistry of Venus’ atmosphere,” Franck Montmessin, who led the research, said in a press release.

The find was made with the help of SPICAV, an instrument aboard Venus Express, which analyzed the starlight around the planet and found characteristic fingerprints of gases in the atmosphere as they absorbed light. Ozone was detectable because it absorbed some of the ultraviolet from the starlight

Previous to this discovery, ozone has been observed on Earth and Mars only. The build-up of oxygen, and consequently ozone, in Earth’s atmosphere began 2.4 billion years ago. Scientists believe the ozone formed as a result of ancient microbes excreting oxygen as a waste gas, along with primitive plant life, which to this day are the main source of replenishing ozone. Greenhouse emissions gathered in the atmosphere in more than 100 years has taken its significant toll on Earth’s ozone along the years. It wouldn’t be too hard for Earth to become a second Venus in the future.

Venus’ ozone layer sits at an altitude of about 62 miles, which is about four times higher in the atmosphere than Earth’s.  ESA said astrobiologists believe that a planet’s ozone concentration must be 20 percent of Earth’s value before life should be considered as a cause of it. Common sense would dictate that on a planet where acid rains and furnace hot surface temperatures dictate, any talk of signs of life would sound trivial, but bacteria and other sorts of micro organisms can find their niche even in the harshest of environments – even on a hellish planet like Venus.

“We can use these new observations to test and refine the scenarios for the detection of life on other worlds,” says Franck Montmessin, who led the research.


Dead human skin gathered in dust is good for the air

Ironically, while most tidy people in the world are busy dusting off furniture, electronics, ceilings, cats, whatnot, researchers have shown in a  recent study that the same dust is actually very good for the air, reducing ozone levels by 2 to 15 percent. All because of dead human skin.

Ozone is crucial for preventing potentially damaging electromagnetic radiation from reaching the Earth’s surface, but in the lower atmosphere, say ground level, it acts as an air pollutant with harmful effects on the respiratory systems of animals and will burn sensitive plants.

Squalene, an oil found on skin cells, has six double carbon bonds in its molecules which interact with, and break apart, ozone. Chemist Charles Weschler and his team analyzed dust from non-floor surfaces in Demark, showing that squalene was more effective than cholesterol, which is another oil found on skin, at removing ozone.

Squalene human skin dust isn’t the only anti-ozone agent found in a household either – other chemicals that contain double bonds between atoms, like oleic acid found in certain cooking oils, and some surfaces, like those made of rubber or neoprene, also consume ozone, according to Weschler. Squalene found in living human skin also shows a contribution to reducing ozone levels, although in a smaller percentage.

“Basically, human beings are large ozone sinks. We have only found this out within the last five years!” Weschler wrote in an email to LiveScience. “In an occupied room humans consume more ozone than dust [does]. However, dust continues to react with ozone even when the room is not occupied.”

The average human sheds around 500 million skin cells per day, which means that your squalene levels will get replenished everyday, and although dust can be considered in this case beneficial, it will build up and at some point dusting is required. Dust can irritate allergies or even pass along microbes, so one should be always careful.

“The skin flakes shed by one person may trigger an allergic response in another person or may serve to pass along microbes that could cause an adverse effect,” Weschler wrote. “While it is a good thing that dust consumes ozone, we should continue to clean — to remove dust. Human occupants will continue to ‘recharge’ squalene in dust and on the surfaces that they contact.”

Story courtesy of Popsci.