Millions of Americans apply personal care products every morning before heading to work or school.
But these products don’t stick to our bodies permanently.
Over the course of the day, compounds in deodorants, lotions, hair gels and perfumes evaporate from our skin and eventually make their way outdoors.

Colorado researchers say over the course of the day, compounds in deodorants, lotions, hair gels and perfumes evaporate from our skin and eventually make their way outdoors.
HOW DO BEAUTY PRODUCTS CAUSE POLLUTION?
The compound in question, decamethylcyclopentasiloxane (or D5 siloxane), contains silicon, which uniquely differs from the organic compounds normally detected.
By reviewing scientific literature, researchers found that pure D5 siloxane is produced mainly as an additive for deodorants and hair care products.
On average, people use products that contain a total of about 100-200 milligrams of D5 every day – roughly the weight of half an aspirin tablet.
Some fraction of these products end up going down the drain when we shower, but the majority of what remains on our bodies ends up in the atmosphere.
D5 concentrations were highest in the morning, the team found – the time when most people shower, apply personal care products and then leave the house to commute to work.
D5 can also be found in many other places, including soil, oceans and the tissues of fish and human beings.
Now there’s new evidence to suggest that these products are major sources of air pollution in urban areas.
For decades, motor vehicles were considered the primary source of air pollutants in major U.S. cities.
Vehicle exhaust contains multiple pollutants that worsen air quality, including nitrogen oxides, particulate matter and volatile organic compounds (VOCs) – a group of reactive gases that contribute to smog formation.
Thanks to advances in catalytic converters and improvements in fuel economy, combined emissions of common pollutants from cars have decreased by 65 percent since the 1970s.
Air pollution is still a problem in urban areas like Los Angeles, but only a fraction of it can be attributed to vehicles.
Today, scientists are finding that other non-combustion sources – including common household products – are also major contributors.
In a recent study with U.S. and Canadian colleagues, our lab found that these sources can include personal care products.
We analyzed urban air in two cities: Boulder, Colorado, and Toronto, Ontario, Canada.
In Boulder, our lab had recently invested in new instrumentation, which we wanted to use to measure wood stove emissions during winter months.
For five weeks we sampled air from the roof of the NOAA David Skaggs Research Center in hope of measuring air parcels contaminated with smoke from residential wood stoves.
Surprisingly, we noticed a signal that stood out unexpectedly from all the other data.
This compound, which we identified as decamethylcyclopentasiloxane (or D5 siloxane), contains silicon, which uniquely differs from the organic compounds we normally detect.

How pollution forms: Volatile organic compounds (VOCs) react in the air with nitrogen oxides to form ozone and smog