Boulder scientists show personal care products’ atmospheric impact – boulder daily camera power quiz questions

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That’s the conclusion of a new study published on Wednesday led by Matthew Coggon, a research scientist who works with the University of Colorado’s Cooperative Institute for Research in Environmental Sciences at Boulder’s National Oceanic and Atmospheric Administration.

The research upon which the new study was based was taken from data recorded in both Boulder and Toronto, detailing the emissions of volatile organic compounds (VOCs) from personal care products such as deodorants, lotions and antiperspirants. Those products react in the atmosphere with nitrogen oxides and other compounds to form ozone and particulate matter, which influence air quality and can have health consequences.

Such health care products evaporate rapidly and emit decamethylcyclopentasiloxane, a mouthful known as D5, or siloxane. Each person emits between 100 and 200 milligrams per day of D5, according to NOAA, which has a long lifespan and can move globally. D5 has been found in the Arctic, in the ocean, in women’s breast milk and even in the livers of Atlantic cod.

Coggon and his team made real-time measurements of ambient D5 in Boulder in 2015 and 2017, and also analyzed samples collected previously in Toronto. They found in both cities that the D5 emission rate is comparable to the emission rate of benzene, which is a marker of vehicle emissions.

"It peaks in the morning and then decays as it off-gases off your body, and it’s of similar magnitude to benzene," Coggon said. "It is going to be highest in the morning, and then slowly decay throughout the day. The morning and afternoon peaks are going to be somewhat comparable.

The new study, published Wednesdayin Environmental Science & Technology, leverages the work of CIRES scientist Brian McDonald, the lead author of a study published in February, which found that chemical products such as household cleaners, paints, perfumes and pesticides that contain compounds refined from petroleum now rival motor vehicle emissions as the top source of urban air pollution.

That earlier work by McDonald — who is also a contributor to Coggon’s new study — used chemical modeling of atmospheric chemistry measurements taken in Los Angeles to show that household products produce roughly 50 percent of the VOC emissions measured there, which is evidence that the impact of household products on VOC emissions is more than previously suspected. Coggon’s team’s study supports those findings.

"So it’s about three to five times lower (than vehicles) in terms of total mass. But the emissions that you see in the morning … they’re fairly close, which is the stunning piece. You driving your car, you’re emitting as much siloxane as your vehicle is emitting benzene. That’s the general gist."

"We don’t really know the toxicity of this compound, and from our standpoint, it’s not that D5 is a toxin in the air or that it’s a major pollutant," Coggon said. "It’s a marker for a really important source of pollution, which are consumer products.

"So, if we see this compound in the atmosphere, we know that air parcel was impacted by people’s deodorant, hair gels and other things. And there’s a whole litany of other compounds that are associated with this that we just don’t know enough about yet. We’re going to be able to do research for the next 10 years, trying to figure out what are the impacts of people putting on their deodorant."

The next phase of their work will include analysis of data already being collected in New York City, which by virtue of its far larger and denser development alone promises to provide a rich array of emissions — and scientific discovery — for the researchers.

"That way, we can start to get a better look at these emissions inventories. They may not have intrinsic air quality impacts, but they are extremely useful for the sciences, to start doing truth-checking on a lot of these different emissions inventories and chemical products."