New research makes a compelling argument for cutting back on personal-care products that may be harmful to the environment. 

Amanda MacMillan
May 02, 2018

When you’re lathering on lotion, applying your makeup, spraying dry shampoo, or dabbing on perfume every morning, you’re probably not thinking much about how those products could affect the air outside your home. But a new study suggests that maybe you should.

Emissions from these types of products now account for a large portion of air pollution in urban areas, say researchers at the University of Colorado at Boulder—especially during the a.m. rush hour when we’re all commuting to work.

It used to be that automobile emissions (along with factories and other industrial sources) made up the vast majority of toxic fumes emitted into the atmosphere in big cities. But cars and trucks have gotten much cleaner over the last 50 years, say Matthew Coggon, PhD, and Carsten Warneke, PhD, research scientists at UC Boulder’s Cooperative Institute for Research in Environmental Sciences.

Now, the researchers say, a significant portion of the emissions recorded during rush-hour traffic aren’t coming from the vehicles themselves. They’re coming from the people inside them–and from the personal-care products they use on their skin and hair.

In a new study published in Environmental Science and Technology, the UC Boulder team measured levels of more than 100 different volatile organic compounds (VOCs) in the air, both from the roof of a research lab and from a mobile laboratory driving around Boulder.

VOCs come from a variety of sources, including car exhaust and off-gassing from everyday household products. When they interact with sunlight, they mix with other compounds to form ozone and particulate matter—two types of pollution that affect air quality and human health.

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Some of the VOCs the researchers found in Boulder were expected—like benzene, a common marker of vehicle exhaust. What was surprising, though, was that levels of another compound—called D5 siloxane—were just as high. Siloxane isn’t present in auto emissions, but it is commonly added to shampoos, lotions, and deodorants to give them a smooth, silky feeling.

The researchers noticed that siloxane levels were highest during the morning rush hour, most likely because that’s when people first left their homes after applying personal-care products in the morning. Levels were lower in the evenings, as most of these products would have evaporated throughout the day.

Emissions from personal-care products make their way into the atmosphere when we have the windows open or spend time outside, say the researchers, but also through the ventilation systems of our cars, homes, and workplaces. They call the mix of chemicals that humans leave behind as they move from place to place their “personal plumes.”

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These findings support another recent study, conducted in Los Angeles, that found that consumer and industrial products—including personal-care products, household cleaners, paints, and pesticides—are now responsible for about half of the VOC emissions measured in urban areas.

“It’s kind of stunning in that, when you think of sitting in traffic behind the tailpipe of a semi-truck, you assume that exhaust is the big contributor to air pollution,” says Coggan. “But now that car engines are much cleaner, we are able to see that emissions are also impacted by personal-care products that people in the vehicle are using.”

The next step, the researchers say, is to learn more about how these emissions affect air quality—and which ingredients, specifically, consumers should be on the lookout for. “We’re not clear yet on what components of these emissions are the biggest contributors to ozone formation or aerosol formation,” says Coggon, “so that’s what we’ll be trying to figure out.”

Fragrances are certainly a big part of VOC emissions, says Warneke. But even products without a noticeable scent can still give off VOCs. “Personal-care products are designed to evaporate,” says Coggon. “Just because you can’t smell something, it doesn’t mean components aren’t still evaporating and interacting with the environment.”

If you've ever wanted to minimize your morning routine or cut back on the number of products you're using on a daily basis, this study may provide some motivation to do just that. After all, while there are certainly companies out there making smart choices for human health and the environment, the beauty and personal-care industries—and the chemicals used in their products—remain mostly unregulated

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The researchers can’t say yet what products people should avoid if they want to contribute less to air pollution. But they do know that emissions from personal-care products are becoming more important, and that consumers should be aware of what they’re putting on their bodies every day.

“We all have a personal plume, and nowadays your personal plume can be just as big of a contributor to ozone as your vehicle,” says Coggan. “You do have a personal choice, so thinking about what products you want to use is certainly something to consider.”