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.
New research from NOAA finds 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, or VOCs, that were generated by people but not produced by 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 of all ages 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 researcher Matthew Coggon, a CIRES scientist working at NOAA who was lead author of the new study.
Now researchers in NOAAs Chemical Sciences Laboratory have turned their attention to two of the largest metropolitan areas in the Southwest U.S. They’ve been on the road since July conducting mobile laboratory and ground-site measurements in collaboration with university colleagues and stakeholders as part of the SUNVEx field research mission, investigating VOCs and other sources of urban air pollution in Las Vegas and Los Angeles.
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. Despite those gains, a groundbreaking paper published by NOAA scientists in 2018 showed that 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 another study published earlier this year in Environmental Science & Technology, which found volatile chemical products including paints, cleaners, and personal care products were responsible for 78% of the Manhattan VOC budget, versus just 22%for transportation.
The lead author of that study, 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, Colorado 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 these volatile consumer products were still responsible for 42% of human-caused VOCs in the local atmosphere, with the transportation sector responsible for the rest. Gkatzelis estimated that averaged nationwide, 50-80% of pollution-forming urban VOCs are associated with volatile chemical products.
Engineered to evaporate
VOCs are a class of carbon-based compounds that arise from many different sources, both natural, like pine forests, and man-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 – including the fragrances featured in a wide array of products – 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
The growing body of work shows that emissions from volatile chemical products are ubiquitous, contributing up to half or more of the total anthropogenic VOC emissions in the U.S. and European cities that were investigated. Vehicle traffic dominates the remainder.
Coggon said the current generation of air quality models do not accurately simulate both the emissions and atmospheric chemistry of these consumer products and must be updated in order to capture their full impact 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.”