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Bottles of sun protectant lotion are seen for sale on Wednesday, August 11, 2021, in Denver. (Olivia Sun, The Colorado Sun)

When Matt Coggon and his team of federal air researchers drive their white utility vans past beaches like Boulder Reservoir on a scorching hot day, their instrument panels instantly detect a cloud of volatile chemicals ascending into the blue Colorado sky.

It’s the sunscreen.

New papers from the National Oceanic and Atmospheric Administration shows that volatile chemicals from personal consumer products make up a large portion of ozone-causing air pollution plaguing Colorado’s Front Range and every major city in America. 

While those fighting air pollution have long assumed volatile organic compounds (VOCs) from automobiles and the oil and gas industry are the largest sources of ozone worth tackling, the research increasingly shows volatile chemicals from consumer products are another major culprit. 

The chemicals that evaporate from consumer products like sunscreen, shampoo, hair gel, bug spray, perfume — even scented garbage bags — make up 42% of human-caused volatile organic compounds in the atmosphere above Boulder, the NOAA research shows. Transportation emissions make up nearly all the rest, said Coggon, a CIRES scientist working at NOAA. 

In densely populated areas like New York, with more consumers and public transit and less industry, the consumer products make up 78% of the total of ozone-causing compounds, their research shows. 

“If someone walks by our van, we can see their plume,” Coggon said. “We can see that happening in real time.” 

Their research was published in Proceedings of the National Academy of Sciences, and follows on similar NOAA findings in cities from New York to Las Vegas to Los Angeles.

Ground-level ozone — separate from beneficial upper-atmosphere ozone that protects the earth from dangerous ultraviolet radiation — is created when VOCs mix with nitrogen oxides and bake under the hot western sun. The resulting compound inflames the lungs, and causes health problems for children with asthma and adults with a variety of respiratory problems or heart conditions. Wildfire smoke drifting from states farther west adds particulate matter, or PM2.5, to the mix, adding to the health impacts. 

Smog is seen near the National Western Stock Show Grounds on Monday, July 26, 2021, in Denver. (Olivia Sun, The Colorado Sun)

Colorado’s health department has declared 51 ozone action alert days in 2021, and appears certain to surpass 2018’s total of 52, the highest since new ozone standards were set in 2016. 

The Environmental Protection Agency has repeatedly lowered the maximum of ground-level ozone allowed in U.S. cities before local governments are required to make stringent pollution cuts. The current standard is 70 parts per billion of ozone. The northern Front Range has been routinely violating those standards for years, and will move into a “severe” nonattainment category from its current “serious” status if the EPA confirms state measurements. 

If there is good news for air pollution regulators in the new NOAA study, Coggon said, it’s that the personal care products and industrial materials like paints and coatings have enough of an impact on ozone that if they were controlled better, it could help some cities reach attainment status. 

“We’ve shown that completely removing volatile chemical products can reduce ozone by as much as five to 10 parts per billion, which gets you underneath the standard in some regions,” he said. 

Air experts have an almost-ironclad rule about human-made ingredients and ozone: If you can smell it, it’s likely bad. The compounds that make a product smell perfumy, clean or industrial-strength are often derived from petroleum-based materials, which become volatile on evaporation. 

Before they began pinpointing their measurements a few years ago, Coggon said, U.S. and European atmospheric researchers assumed the vehicle traffic highly visible in every city was mainly responsible for ozone-related pollution. But cars have been getting cleaner for decades, and cities once famous for smog have had some success in cutting transportation-related emissions. 

The instruments the NOAA researchers pointed at homes, apartments and public gathering sites can pick up pollutants in the parts per trillion. The researchers have driven behind city trash trucks filled with lotion bottles, paint cans, makeup kits and countless other consumer products, and have tracked the resulting cloud in real time. 

“It’s a little stunning even to us,” Coggon said. “People just throw this stuff into the trash, and we can see it. Everything we do just ultimately ends up in the atmosphere. I like to think of the home as the new tailpipe.” 

The contribution of consumer products to ozone pollution is significant, Coggon said, but researchers and manufacturers in the past have been able to make product changes that reduced ozone-producing evaporation. Paint manufacturers, for one, have altered the molecular structure of their mixes in order to release fewer volatile chemicals into the air. 

The NOAA researchers do not make policy recommendations as a rule, Coggon said. But it should be clear from the precision of the research that new efforts to limit or reformulate consumer chemical releases could be part of overall air pollution control efforts, he said. 

“It’s another tool in the strategy,” Coggon said. 

Colorado’s state Air Pollution Control Division said it recognizes the contributions of consumer products to the ozone problem, and has moved to limit their impact. The state Air Quality Control Commission passed Regulation 21 in 2019 that took aim at some consumer products and architectural and industrial maintenance coatings, said Jessica Bralish, spokeswoman for the Colorado Department of Public Health and Environment.

The regulation required certain products sold starting in 2020 to meet new standards, Bralish said. The state will evaluate any new research on ozone precursors, she said, and also monitor results of regulations in California, which has imposed complex rules about chemical use. 

As for what consumers themselves can do about the chemicals, Coggon suggested looking for home maintenance and cleaning products that are water-based or which are labeled as low-VOC content. 

People can limit their use of chemical or fragrance-laden personal care products like deodorants and perfumes, he added. But they might want to check with their partners or families first. 

Michael Booth is The Sun’s environment writer, and co-author of The Sun’s weekly climate and health newsletter The Temperature. He and John Ingold host the weekly Sun-Up podcast on The Temperature topics every Thursday. He is co-author with...