LOS ANGELES--When it comes to air quality, the products you use to smell nice or scrub your kitchen could be just as bad as the car you drive. A new study of the air around Los Angeles finds that consumer and industrial products now rival tailpipe emissions in creating atmospheric pollutants.
The findings, published Thursday in the journal Science, reveal a shift in the balance of polluting power in cities -- one that may prompt researchers and regulators to focus even more on a wide range of common consumer and industrial goods like hairspray, paint and deodorant.
Air pollution exposure is a leading cause of health problems worldwide. Among risk factors to human health, it ranks fifth behind malnutrition, poor diet, high blood pressure and tobacco, according to a report last year in the journal Lancet.
Much of the stuff in air pollution forms from reactions with volatile organic compounds, or VOCs, a wide range of carbon-based chemicals that easily escape into the air and that humans produce in huge amounts.
In the past, car exhaust was responsible for much of those man-made VOCs. That's been especially true in Los Angeles, a freeway-laced land of long commutes that a few decades ago was wreathed in dark, heavy layers of smog.
But as restrictions on tailpipe emissions have tightened and automotive technology has improved, the amount of VOCs has dropped and the air has cleared. (Cars still produce tons of carbon dioxide, an invisible greenhouse gas that scientists say is contributing to global warming, but that's another story.) Scientists wanted to see what that meant for L.A.'s air pollution profile.
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"As the mix of chemicals in the atmosphere has changed, how is that impacting air quality in the region -- and generally, in any urban environment?" said study co-author Christopher Cappa, an environmental engineer at the University of California, Davis.
Cappa and his colleagues looked at data on the contents of outdoor air to see what pollutants they would find. They soon noticed that levels of certain VOCs, like ethanol and acetone, were far too high to be explained by vehicle emissions alone.
"That implies that there's some other source," Cappa said.
The scientists went looking for those sources. They found that many common products, including pesticides, coatings, paints, printing inks, adhesives, cleaning agents and personal care products such as body spray and hairspray, were full of volatile organic compounds that could be released into the air.