Tag Archives: pollutants

People are the “dominant source” of volatile organic compounds in the office

New research at Purdue University measures how much pollution in your office or home is due to you.

Image via Pixabay.

We influence our surroundings just by virtue of being alive — we take oxygen and pump out CO2, our skin sheds, our hairs fall out, our heat dissipates out. Factor in elements like deodorant, and we have a surprisingly significant effect on the areas we spend our time in, such as an office or home. But, to find out just how large this influence is, a team of engineers at Purdue University has been conducting one of the largest studies of its kind in the office spaces of a building rigged with thousands of sensors.

The house of noses

“If we want to provide better air quality for office workers to improve their productivity, it is important to first understand what’s in the air and what factors influence the emissions and removal of pollutants,” said Brandon Boor, an assistant professor of civil engineering with a courtesy appointment in environmental and ecological engineering.

The present study is the largest of its kind to date. The team used an office space rigged with thousands of sensors to identify all types of indoor air contaminants and recommend ways to control them through adjusting a building’s design and operation. The building is called the Living Labs at Purdue’s Ray W. Herrick Laboratories and uses an array of sensors to monitor the flow of indoor and outdoor air through the ventilation system over four open-plan office spaces. The team further added temperature sensors (embedded in each desk chair) to keep track of people’s activities throughout the day.

People and ventilation systems have shown the greatest impact on the chemistry of indoor air in such environments, they explain. This chemistry is dynamic and “changes throughout the day based on outdoor conditions, how the ventilation system operates and occupancy patterns in the office,” Boor said.

In collaboration with researchers at RJ Lee Group, Boor developed an instrument called a proton transfer reaction time-of-flight mass spectrometer — a mechanical ‘nose’. Using this device, they recorded levels of volatile compounds in human breath, such as isoprene, in real-time.

These compounds linger in the office even after people have left the room. They also see greater build-ups when a larger number of people uses the same room.

“Our preliminary results suggest that people are the dominant source of volatile organic compounds in a modern office environment,” Boor said. “We found levels of many compounds to be 10 to 20 times higher indoors than outdoors. If an office space is not properly ventilated, these volatile compounds may adversely affect worker health and productivity.”

Ozone (considered an outdoor pollutant) breaks down inside office areas as it interacts with indoor compounds and furnished surfaces. The team adds that ozone and compounds called monoterpenes (these are aromatic compounds, such as those released by peeling an orange) break down into particles as small as one-billionth of a meter. At such a tiny size, they could be toxic as they can get into — and clog — pulmonary alveoli, the sacs in the lungs where blood-atmosphere gas exchange takes place.

Chemicals emitted from self-care products such as deodorant, makeup, and hair spray may elevate pollution levels outdoors as they are vented outside by the ventilation system, the team adds.

The team will present its initial findings at the 2019 American Association for Aerosol Research Conference in Portland, Oregon, on Thursday 16th, as the poster “Spatiotemporal Mapping of Ultrafine Particles in Buildings with Low-Cost Sensing Networks”.

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.