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Air Quality Plans Focused on Tailpipes May Be Missing Summer Pollution Sources
In A Nutshell
- Over a summer month in one New York suburb, everyday chemical products such as perfume, cleaning spray and paint made up about 40% of measured air-polluting gas emissions, compared with 31% from traffic.
- Heat drives the shift: warm weather speeds evaporation from products and boosts releases from plants and homes, while traffic took the top spot in winter.
- A federal emissions database overestimated winter emissions by about 2.5 times, in part because its estimates barely changed between seasons.
- Results come from one suburb measured for about a month in summer and 20 days in winter, so other cities will need their own checks.
Tailpipes have long been the prime suspect for dirty city air. Over a summer month in one New York suburb, though, chemical products used in homes and businesses, from perfume and lotion to cleaning spray and paint, put more air-polluting gas into the sky than traffic did. Added up, those products accounted for about 40% of the area’s summer emissions of gases called volatile organic compounds, compared with 31% from traffic, according to a new study in Science Advances.
Winter reversed the ranking. When temperatures fell, those products gave off far less gas, and traffic, whose output held steadier year-round, took the top spot. Heat was the deciding factor: warm weather makes products evaporate faster and pushes plants and homes to release more.
That matters because these gases react with sunlight and other chemicals in the air to form ozone, a main ingredient of smog, and fine particles, both linked to breathing and heart problems. A federal database that estimates pollution from each source missed the seasonal swing, overestimating winter emissions by about 2.5 times.
Tower Readings Show Summer Air Pollution Gases Roughly Doubled
Estimating pollution from air samples can mislead, because wind and chemical reactions shuffle gases around after release. Here, daily rises and falls in how much of a gas hung in the air did not track how much was being released.
A team from Colorado State University, the University of Minnesota and other institutions instead measured what was actually rising off a neighborhood. They mounted instruments on a cell tower in Mineola, New York, about 17 miles from New York City, where homes, restaurants and a major highway fill a densely populated suburb. Sensors about 107 and 197 feet up tracked which gases were rising and which were being absorbed. Readings ran for about a month in summer 2023 and 20 days in winter 2024.
Summer emissions came out to more than double winter levels, and their total potential to form ozone and particles rose even more sharply. The tower picked up 126 different gases in summer but only 50 in winter. Ethanol, which comes from traffic, cooking and chemical products, led the list in both seasons, making up 22% of summer emissions and 28% of winter emissions.
Everyday Products Edged Out Traffic in Summer Air Pollution
To pin each gas on a source, the team sorted the readings by chemical makeup, time of day and wind direction. Five groups emerged. Chemical products, the top group when counted together, came from personal care products, cleaning products and paints spread across the area, plus specific businesses such as auto repair shops and lawn care operations. Traffic, the runner-up, showed rush-hour peaks around 8 a.m. and 5 p.m. and roughly half as much output on weekends, a sign that nearby roads serve largely as commuter routes.
Plants and homes added 23%. That group included chemical traces from building materials, such as wood, that break down faster in hot attics. Restaurant cooking made up 6% in summer, with its peaks centered on a cluster of restaurants north-northwest of the tower.
Several clues point to heat. Emissions from the spread-out chemical products climbed as temperatures rose, and the link was stronger over pavement and rooftops than over lawns and trees. Other cities point the same way. A separate study in Beijing found chemical products outranking vehicles, at about half of measured gas emissions versus 24%. An earlier study in Los Angeles found heat-sensitive emissions, mostly from plants, accounted for about 60% of the summer ozone and particle pollution those gases can form.
Cold Weather Put Traffic Back on Top and Exposed Gaps in a Federal Database
Winter shrank the heat-driven sources enough to hand traffic roughly half of the total. Traffic emissions dropped only about a quarter from summer, while chemical products, plants and homes slid from 63% of emissions to 40%. Frying-related gases from restaurants also disappeared, and cooking emissions shifted toward midday and evening peaks that match home kitchens.
Those swings tripped up the federal database. Because it covers only human-made sources, researchers set aside plant-driven emissions before comparing. Its figures changed by only about 4% between seasons, while measured human-made emissions fell by more than a third. Restaurant cooking was one big miss, with the database running up to 9.1 times too high, possibly because it assigns cooking emissions by population instead of by restaurant count. Menu choices matter, too: a separate study found tofu stir-fry released three to four times more ethanol than chicken stir-fry. Traffic went the other way, underestimated by about three times in both seasons.
Air quality plans built around tailpipes alone leave out a big piece of the summer picture. Databases that overstate restaurant cooking can exaggerate the payoff of exhaust scrubbers, while those that miss the heat effect may overlook side benefits of fixes such as urban greening. If summers keep getting hotter, particularly during heat waves, counting the heat effect could become an important part of protecting public health, alongside efforts to cut traffic pollution.
Disclaimer: This article is based on peer-reviewed scientific research but is intended for informational purposes only and is not intended to serve as medical advice, diagnosis, or treatment. Always consult a licensed physician or qualified healthcare provider with any questions regarding a medical condition.
Paper Notes
Limitations
Findings come from a single suburban footprint in the New York City area, measured for about a month in summer 2023 and 20 days in winter 2024. The authors note that emission sources, chemical makeup, and the link between temperature and evaporation can vary across cities and years, so more measurements in a wider range of places are needed. The instrument has low sensitivity to certain gases, including straight-chain and branched alkanes, and the analysis excludes others, such as formaldehyde, that can matter for city air chemistry. The authors estimate that unmeasured alkanes could add about 25% to summer emissions. The database comparison used 2021 estimates for a grid cell about 2.5 miles on each side, larger than the area the tower sampled. Calibration and calculation uncertainty could raise summer totals by up to 80% or lower them by 31%, and could raise winter totals by 41% or lower them by 18%, without changing the seasonal pattern. The five source groups are described as dominant categories rather than pure sources, because some mixing is expected when sources overlap in space and time.
Funding and Disclosures
Support came from the National Oceanic and Atmospheric Administration (NOAA) Climate Program Office’s Atmospheric Chemistry, Carbon Cycle, and Climate Program, the New York State Energy Research and Development Authority, and a National Science Foundation MPS-Ascend fellowship. The authors declare no competing interests.
Publication Details
Michael P. Vermeuel, Dylan B. Millet, Róisín Commane, Timothy J. Griffis, Trey A. Maddaleno, Emily B. Franklin, Katelyn L. Richard, Rose K. Rossell, Jeff Peischl, and Delphine K. Farmer wrote the study, “Surface temperatures drive strong seasonality in urban reactive carbon emissions.” Millet (University of Minnesota) and Farmer (Colorado State University) are the corresponding authors. It was published in Science Advances, a journal of the American Association for the Advancement of Science, volume 12, issue 41, article eaef9622, on October 7, 2026, after being submitted February 6 and accepted September 3, 2026. DOI: 10.1126/sciadv.aef9622.
