Want Cleaner Air? Try Using Less Deodorant

Want Cleaner Air? The deodorants, perfumes and soaps that keep us smelling good are fouling the air with a harmful type of pollution — at levels as high as emissions from today’s cars and trucks.

That’s the surprising finding of a study published Thursday in the journal Science. Researchers found that petroleum-based chemicals used in perfumes, paints and other consumer products can, taken together, emit as much air pollution in the form of volatile organic compounds, or V.O.C.s, as motor vehicles do.

The V.O.C.s interact with other particles in the air to create the building blocks of smog, namely ozone, which can trigger asthma and permanently scar the lungs, and another type of pollution known as PM2.5, fine particles that are linked to heart attacks, strokes and lung cancer.

Smog is generally associated with cars, but since the 1970s regulators have pushed automakers to invest in technologies that have substantially reduced V.O.C. emissions from automobiles. So the rising share of air pollution caused by things like pesticides and hair products is partly an effect of cars getting cleaner. But that breathing room has helped scientists see the invisible pollutants that arise from a spray of deodorant or a dollop of body lotion.

The researchers said their study was inspired by earlier measurements of V.O.C.s in Los Angeles that showed concentrations of petroleum-based compounds at levels higher than could be predicted from fossil-fuel sources alone. Concentrations of ethanol, for example, were some five times higher than expected. And those levels were increasing over time.

“You can see these really rapid decreases in tailpipe emissions,” said Brian C. McDonald, a scientist at the Cooperative Institute for Research in Environmental Science at the University of Colorado, Boulder, who led the study. “It just made sense to start looking at other sources and seeing whether they could be growing in relative importance.”

Even though drivers can use gallons of gasoline each week, “it’s stored in an airtight tank, it’s burned for energy, and converted mostly to carbon dioxide,” said Jessica B. Gilman, a research chemist at the National Oceanic and Atmospheric Administration also involved in the study. Those carbon dioxide emissions are not smog-forming V.O.C.s, though they are a major driver of human-caused climate change.

“But these V.O.C.s that you use in everyday products — even though it may just be a teaspoon or a squirt or a spray — the majority of those kinds of compounds will ultimately end up in the atmosphere, where they can react and contribute to both harmful ozone formation and small-particle formation,” Dr. Gilman said.

Forty percent of the chemicals added to consumer products wind up in the air, the researchers found.