Dr. Maria Wei, a professor of dermatology at the University of California, San Francisco, was helping a student come up with a project about how the environment affects skin when she looked out her office window and saw the ash falling from the sky. It was the first day of the California Camp Fire — the 2018 wildfire that was, at the time, the state’s deadliest and most destructive.
“I wondered how it would affect the skin, especially since I’d just biked in to work,” she said.
The study, published by Wei, her student, Raj Fadadu, and some of their colleagues in June, was the first to link skin disease (atopic dermatitis, aka eczema) to wildfire smoke.
It won’t be the last.
As climate change makes wildfires increasingly frequent and devastating — and as smoke from flames blows across the country — scientists are just beginning to untangle all the ways the changing environment threatens human health, including via the skin, the body’s largest and most exposed organ. Of course, beauty companies are right there with them, offering, among other things, products labeled “antipollution” or “pollution protection.”
You don’t need any of them.
But for anyone who has bandwidth enough to spare for skin care these days — and for those who don’t have the luxury of staying indoors — here’s what we know about what pollution does to your skin, and what you can do about it.
When researchers talk about pollution exposure, they’re generally talking about particulate matter smaller than 2.5 microns. (A human hair is at least about 20 microns in diameter.) These can get in the bloodstream, affect every organ and have a range of potentially frightening implications. Dermatologists, though, are interested in how these particles land on the skin — and possibly penetrate it — and create a cascade of inflammation, accelerating signs of aging and causing disease. Studies have already shown that air pollution increases wrinkles and age spots.
“We all sort of know that when someone is a chronic smoker, they have that aged appearance and that yellow, sallow skin,” said Dr. Markus Boos, a pediatric dermatologist at Seattle Children’s hospital who has studied climate change and skin health. “It’s kind of a variation on that.”
There are dozens of kinds of pollutants that produce the free radicals that damage lipids, proteins and DNA in skin cells, weakening the skin barrier. Some pollutants trigger receptors that regulate detoxifying proteins — a good thing — but at the same time stimulate other inflammatory pathways that make the skin more sensitive and leach it of water. The result: dry, scaly skin.
Things get worse when pollution mixes with ultraviolet, or UV, light. The combination of the two is synergistic, not additive. Particles in car exhaust, for example, are overactivated by sunlight, making them even more toxic, said Giuseppe Valacchi, a professor of regenerative medicine at North Carolina State University, whose lab simulates pollution so he can study its effect on the body. The combination of pollutants and UV also depletes the skin’s supply of antioxidants faster.
“It’s pretty dramatic,” said Dr. Karen Burke, an assistant clinical professor of dermatology at the Icahn School of Medicine at Mount Sinai in New York and an author of a study on UV light and pollution. The combination also causes more oxidative damage to cells, which leads to premature aging and skin disease, she said.
Underestimating wildfire’s effect
The specific effects of wildfire pollution on the skin are less clear, in part because every wildfire is unique depending on what it burns (building materials? trees? bushes?), its intensity and its temperature. The most toxic compounds are created at the highest temperatures, Valacchi said.The eczema and wildfire study focused on that disease because afflicted people have an impaired skin barrier, meaning they would be more likely to have a reaction to smoke, Wei said.
Some 7% of adults and 15% of children in the United States have eczema, but it’s not yet clear how this translates to the rest of the population since it’s not known if the incidence and severity of skin disease intensifies as pollution does, or if there’s a threshold of pollution at which the skin barrier completely fails, she said. (Exposure to air pollution from cars and industry takes place over a long period; wildfires are generally short but create intense exposure to hazardous air, Fadadu said.)
In the study, visits to the dermatology clinic for itches were up significantly during the roughly two weeks of the fire in November, and 89% of adult patients had no previous diagnosis. (During the same time period in previous years, some 50% of patients with eczema had no previous diagnosis.) Researchers don’t know if these people had subclinical eczema and the fire “unmasked it,” Wei said, or if “these were normal folks who actually had symptoms of eczema from the fire.”
Either way, Dr. Misha Rosenbach, an associate professor of dermatology at the University of Pennsylvania and a chair of the Climate Change and Environmental Affairs Expert Resource Group of the American Academy of Dermatology, said the impact of wildfires on skin was very likely much greater than what we knew now. He praised the eczema study but said it probably underestimated wildfires’ effects — most people with rashes tend to go to emergency rooms or their doctors, not dermatology clinics, which were the study’s data set.
Also, the study took place in San Francisco, 175 miles from the source of the fire. “We’ve had many days on the East Coast where the air quality is the worst it’s ever been because of the West Coast fires,” he said.
“This is a totally nascent field, so over the next five or 10 years, people who are interested in this are going to publish epi study after epi study after epi study” — that’s epidemiological — “showing increased flares of disease x, y and z after exposure to air pollution,” he added.
How to protect yourself
On poor air quality days caused by wildfires, wear long sleeves, long pants and a mask, Wei advised. You could also apply an emollient, which gives your skin an artificial barrier, she said.
Doctors and scientists agree that you almost certainly do not need to buy anything labeled “pollution protection” for everyday use.
“Companies like to look for exotic new compounds, and some are just marketing because there is no way they can be absorbed by the skin,” Valacchi said.
Dr. Whitney Bowe, a dermatologist in New York, advises applying a moisturizer or serum with ceramides to help create a physical barrier to which the tiny particles can stick (and so not penetrate the skin). Makeup doesn’t help much here, by the way — most foundations don’t have sufficient moisturizing properties to do the job, Bowe said.
Of course, this makes cleansing at night especially important, because “you don’t want all the pollutants you have been exposed to to sleep with you,” Valacchi said. Scrubbing can damage the same skin barrier you’ve been trying to bolster, so stick to using your fingers.
Besides the moisturizer, some dermatologists recommend vitamin C, which neutralizes free radicals. When you cut an apple or a banana and it almost immediately turns brown, that’s vitamin C oxidizing and protecting the fruit. But it’s because vitamin C is so active — and so unstable — that it’s extremely difficult to put in a beauty product, which means some companies use forms that either aren’t absorbed by the skin or aren’t able to act as an antioxidant, Burke said.
“So many topical creams just totally don’t work,” she said.
The label should say l-ascorbic acid — the only active form on the skin, Burke said — and for best results, you want a 15 to 20% concentration.
Better than vitamin C on its own is a product that combines vitamin C and vitamin E, which are synergistic — and regenerate each other, Burke said. For what it’s worth, all of the doctors willing to recommend products for this article recommended Skinceuticals C E Ferulic, $166.
You may also want to consider selenium, a trace mineral that’s a cofactor in a free radical-quenching enzyme called glutathione peroxidase. In one study volunteers who took selenium (in the form l-selenomethionine) got far fewer sunburns. You could take 100 micrograms a day or — if you’re not a fan of daily supplements — Burke recommends taking l-selenomethionine for the three weeks before any sun vacation, and also during the vacation itself.
“You get a reservoir of antioxidant protection in your body,” she said. (Burke’s research has shown that selenium is actually more effective as a topical cream, but there isn’t one yet because the mineral’s smell — like rotten eggs — is tough to mask.)
Another way to get that reservoir of antioxidants: Eat them. Polyphenols, the powerful antioxidants that give plants their bright colors, help protect skin from the inside out.
“I tell my patients to eat the rainbow,” Bowe said. It certainly can’t hurt.