Everyday chemicals rival cars as a source of air pollution

Los Angeles Times

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.

“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.

Given that many of these VOC-containing products are used indoors, the scientists checked previous research on the air quality of interior spaces. Sure enough, the indoor concentrations of VOCs from these products were roughly seven times higher than they were in ambient air.

Cappa and his colleagues believe that some of those compounds were probably leaking out of those buildings and polluting the greater environment.

Putting all of this together to create a coherent portrait of air pollutant sources was no easy task, said John Seinfeld, an atmospheric chemist at Caltech who was not involved in the paper. “It’s a landmark accomplishment to have done this,” Seinfeld said. “It will stand as an important piece of work.”

Keep in mind, scientists said, VOC-filled products like deodorant and hand sanitizer account for only about 5 percent of the oil and natural gas used in Los Angeles. The vast majority is used to make fuel, including the stuff that goes into your gas tank.

And yet, consumer and industrial products emit roughly the same level of VOCs as fuel-burning vehicles.

Part of the problem is in the very nature of these household items, scientists said. While fuel is meant to be burned, the VOCs in many consumer products are meant to escape into the air.

“Many of the volatile chemical products that we use every day are intended to simply evaporate,” said study co-author Jessica Gilman, a research chemist with the National Oceanic and Atmospheric Administration. “Think of using hand sanitizer in cold and flu season, scented products, the time spent waiting for paint, ink and glue to dry.”

All of these, she said, involve “waiting for these volatile chemical products to evaporate.”

The study authors pointed out that while U.S. regulations on VOC-containing products emphasize the need to mitigate the ozone and other toxins that are created when VOCs react in the atmosphere, those regulations currently exempt many chemicals that lead to secondary organic aerosols — which make up much of urban air pollution.

This new work points to a need to adapt research, and perhaps tailor regulations, to the changing pattern of emissions in cities, said Alastair Lewis, a researcher at the University of York in England who was not involved in the research.

“As knowledge of VOC chemistry improves, it will become possible to develop more targeted approaches to reducing impacts,” Lewis wrote in a commentary that accompanied the study. “Prioritizing those VOCs with the greatest aerosol formation potential — for example, through reformulation of consumer products — would be one option. Industry sectors that have until now been left outside of VOC emissions controls may, in a cleaner electrified future, receive more direct attention from regulators.”

But figuring out exactly which VOCs are the most problematic will take more research, the scientists said.