The deodorant you roll on in the morning, the sun block you slather on in the afternoon, and the bug spray you apply at night all contribute to what’s become a significant source of air pollution in urban areas such as Philadelphia, according to a new study led by the National Oceanic and Atmospheric Administration.

Add to that dryer sheets, air fresheners, cleaners, and just about anything that emits a fragrance.

The new research from NOAA found that personal care products can generate half or more of the volatile organic compounds (VOCs) in an urban area. VOCs, a class of carbon compounds, are a primary ingredient in forming ground-level ozone.

Ground-level ozone is created by chemical reactions between oxides of nitrogen (NOx) and volatile organic compounds (VOC), combined with the reaction under sunlight, one reason why it is likely to reach unhealthy levels on hot sunny days in a city. Ozone can be harmful to people, especially those with asthma, as well as children, older adults, outdoor workers, and those who are otherwise active outdoors.

Pollutants emitted by cars, power plants, industrial boilers, refineries, chemical plants, and other sources are often cited as the chief cause. Decades of regulations on motor-vehicle tailpipe emissions have helped to greatly reduce VOCs.

However, volatile chemical products (VCPs) are now responsible for much of the petrochemical VOCs emitted in major urban areas, according to the findings published this week in the Proceedings of the National Academy of Sciences.

VCPs are a category of VOCs.

The study looked at overall ozone pollution in Philadelphia but did not specifically break out how much of that was due to VCPs. But it did look closely at Manhattan. There, the research found about half of VOCs collected from air samples in 2018 could be attributed to products that produce volatile chemicals.

“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,” researcher Matthew Coggon, a CIRES scientist working at NOAA who was lead author of the new study, said in a statement.

Coggon’s study built on another report published earlier this year in Environmental Science & Technology that found VCPs in consumer products, which also included paints and cleaners. That research found that more than three-quarters of VOCs in Manhattan, compared with about one-fifth for transportation, were generated by VCPs.

VCPs must evaporate in order to function. They carry scents as in dryer sheets, for example, or cause a residue to stick to a surface, such as in bug spray. The evaporating ingredients are typically derived from fossil fuels.

Though the research says VCPs have become near ubiquitous, current air-quality models do not accurately capture their emissions.

“We know now that these products are making ozone pollution worse,” Coggon said.

The research was carried out with the help of scientists from the University of Colorado, University of Maryland, City College of New York, NASA, Virginia Polytechnic Institute, University of Kansas, and Switzerland-based Tofwerk.