Cooperative Institute for Research in Environmental Sciences at the University of Colorado Boulder

Fragrant Consumer Products a Key Source of Ozone-Forming Pollution in New York City

CIRES and NOAA scientists now turning their attention to Las Vegas and Los Angeles

It’s hot. Time for deodorant, sun block, and bug spray; some conditioner to keep your hair from turning to straw; and maybe a little air freshener for the laundry room where a damp pile of workout clothes awaits.  

A new CIRES-led study found that personal care products like these are now responsible for a significant amount of the ozone pollution known as smog that plagues major urban areas. In New York City, for example, air samples collected during a 2018 field mission by an instrumented NOAA mobile laboratory showed that fragrant personal care products generated about half of the volatile organic compounds (VOCs) produced by people but not vehicle exhaust. VOCs are a primary ingredient in the formation of ground-level ozone, which can trigger a variety of health problems in children, the elderly, and people who have lung diseases such as asthma.

The findings were published this week in the Proceedings of the National Academy of Sciences.

“The big takeaway is how much VOC emissions from consumer products increase as urban population density increases, and how much these chemicals actually matter for producing ozone,” said Matthew Coggon, a CIRES researcher working at NOAA and lead author of the new study. 

Now, researchers in NOAA’s Chemical Sciences Laboratory have turned their attention to two of the largest metropolitan areas in the southwest United States, Las Vegas and Los Angeles. They are conducting mobile laboratory and ground-site measurements in collaboration with university colleagues and stakeholders as part of the SUNVEx field research mission, which is investigating VOCs and other sources of urban air pollution.

A new threat to air quality emerges 

For decades, air quality regulators made progress in reducing urban smog by controlling VOCs generated by the transportation and electric power sectors. In 2018, a groundbreaking paper published by CIRES and NOAA scientists showed that, despite those reductions, fossil fuel-based chemicals in a wide range of consumer products had emerged as a rival to tailpipes as a source of VOCs.

Coggon’s study built on a study published earlier this year in Environmental Science & Technology, which found that volatile chemical products (VCPs) including paints, cleaners, and personal care products were responsible for 78 percent of the Manhattan VOC budget, versus just 22 percent for transportation. 

this map shows the route driven by the NOAA CSL mobile lab from Boulder, colorado, to New York City, with a 3-D representation of population density. The pie charts show the fractions of human-caused VOC emissions that can be attributed to Volatile Chemical Products and vehicle traffic for Boulder and New York City. CREdit: chelsea Thompson, cires/noaa (published in Gkatzelis et al., 2021)

The lead author of that study, former CIRES scientist Georgios Gkatzelis, said he was initially skeptical that consumer products could play such a big role in ozone pollution. “Seeing all those cars when biking to work in Boulder convinced me they had to be the dominant VOC source,” said Gkatzelis, now a research scientist in Germany. “But after driving our NOAA van though New York City and watching our instrument displays, Matt and I were often shouting at each other in amazement at what we were seeing.” 

Measurements taken in much less densely developed Boulder, Colorado, showed VCPs were still responsible for 42 percent of human-caused VOCs in the local atmosphere, with the transportation sector responsible for the rest. Gkatzelis estimated that averaged nationwide, 50-80 percent of pollution-forming urban VOCs are associated with VCPs.

Engineered to evaporate

VOCs are a class of carbon-based compounds that arise from many different sources, both natural, like pine forests, and human-made, like fossil fuel emissions. Volatile chemical products are a category of VOCs that share two common characteristics. Key ingredients must evaporate in order for them to function, to carry scent for example, or to cause a residue to stick to a surface. These evaporative ingredients are typically derived from fossil fuels. 

VOCs are one of two critical constituents needed to produce ground-level ozone pollution and urban smog—nitrogen oxides (or NOx) being the other. In the air, sunlight can trigger VOCs to react with NOx to form ozone and particulate matter. Air quality regulations typically target both to control ozone pollution.

A new challenge for health officials 

A growing body of work shows that VCPs are ubiquitous, contributing up to half or more of the total anthropogenic VOC emissions in the U.S. and European cities that the researchers investigated. Vehicle traffic dominates the remainder.

According to Coggon, current air quality models do not accurately simulate both the emissions and atmospheric chemistry of these VCPs, so the models must be updated to capture the full impact of VCPs on urban air quality. In areas where ozone pollution is a problem, new strategies to control VOC sources may need to be devised, he said.

“We know now that these products are making ozone pollution worse,” Coggon said. “We can’t control what the trees are emitting, but what we can do is look for ways to make these common everyday products less polluting.” 

This story was written by NOAA Communications.

CIRES at CU Boulder has partnered with NOAA since 1967.


Matt Coggon
CIRES and NOAA scientist
Karin Vergoth
CIRES Communications
Theo Stein
NOAA Communications

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