Wildfire Smoke Linked to New and Worsened Eczema, Study Finds

Exposure to wildfire smoke can wreak havoc on the lungs, heart, and other vital organs. Now, scientists are learning how this air pollution may harm the skin—our largest and most exposed organ.

One recent fire called the Camp Fire, burned near the San Francisco Bay Area from October 2018 to February 2019. It spewed ash and smoke, polluting the air of thousands of Californians. Maria Wei, MD, PhD, professor of dermatology at the University of California, San Francisco, says she watched ash rain from the sky and knew she needed to study how it impacted skin health.

“Our skin is the largest organ,” Wei tells Verywell. “It's out there, contacting the environment 24/7.”

As it turns out, there was a significant uptick in the number of both adult and pediatric patients visiting health clinics in San Francisco complaining of itchiness and eczema. The data was published last month in the journal JAMA Dermatology by researchers at the University of California, San Francisco, in collaboration with researchers at the University of California, Berkeley.

Quick Impact

The research team analyzed more than 8,000 dermatology clinic visits by more than 4,100 pediatric and adult patients over the course of the fire’s burn. They recorded patients’ reports of atopic dermatitis— or itchiness—before, during, and after the fire. They compared these numbers to the number of visits during the same time frame between 2015 and 2016.

During the fire, the rates of visits for eczema among children were 1.5 times greater than the number of visits during the nonfire period, adjusted for temperature, relative humidity, patient age, and total patient volume at the clinics. For adults, the number of visits was 1.15 times greater. Additionally, they found that 89% of the patients that experienced itch during this period did not have a known previous diagnosis of atopic dermatitis, also known as eczema.

Studies from other parts of the world indicate that air pollution from sources like traffic and industrial emissions can impact skin health. To understand the specific effects of wildfire smoke, the researchers chose a population that is typically exposed to relatively low amounts of air pollution but experienced a large increase as a result of proximity to a wildfire.

“The surprising thing was the effect was so quick,” Wei says. “Pollution has a very quick effect, and the effect is dramatic, requiring in some cases systemic medications like steroids.”

Even short bursts of exposure to the smoke, it appears, can noticeably damage the skin barrier. For people with eczema, the skin is usually already susceptible to dryness and inflammation.  The additional irritants from air pollution can cause flare-ups and itchiness.

For people with normal skin, too, the air pollution seems to cause itchiness and other symptoms of eczema. “Even normal skin, which is working perfectly normally as a barrier, has its limits," Wei says. "And you can overcome the good barrier function if you stress it enough, like with enough pollution."

The study is “intriguing” because a large number of patients felt the physical effects of atopic dermatitis, rather than just seeking a preventative evaluation, Lawrence Eichenfield, MD, director of pediatric dermatology at the University of California, San Diego School of Medicine and Rady Children's Hospital, San Diego, tells Verywell.

“It really reflects this influence of the external environment on the skin of this large population,” Eichenfield says.

Pollutants in Wildfire Smoke

Wildfire pollution contains fine particulate matter called PM2.5. These tiny particles are known in the medical community for getting lodged in the lungs and bloodstream, in turn causing problems for internal organs. Even though San Francisco is 175 miles from the origin of the Camp Fire, the city saw a nine-fold increase in baseline P2.5 levels.

Smoke contains various gases and liquids which can penetrate the outer barrier and damage cells. These can disrupt gene transcription and trigger oxidative stress or cause inflammation.

Though many wildfires mostly burn through vegetation, the Camp Fire incinerated a large residential area. The particular toxins released into the smoke from this type of burn may have impacted how the air pollution penetrated and damaged skin.

“We know that there's a variety of chemicals in the air: carbon monoxide, carbon dioxide, nitrogen oxides, organic compounds as well as particulate matter,” Eichenfield says. “It's very important for us to figure out which of those is the one that might have trigger triggered the actual flares in these patients.”

Additionally, Wei says the research doesn’t explain what amount of air pollution triggers a response in the skin. It’s also yet unclear if prolonged exposure impacts the skin differently compared to short-term exposure. It’s possible, Wei says, that the closer someone is to the source, the more pronounced the effect of the smoke on their skin, though more research is needed to know for sure.

How to Protect Your Skin During Wildfire Season

If you live in a place impacted by wildfires or you expect to be exposed to smoke, the best way to avoid skin damage during these periods of time is by remaining indoors, especially when the air quality is particularly bad. Indoor air conditioning can be especially helpful, as it can remove toxins and keep out heat—a possible trigger for eczema.  

“Patients with atopic dermatitis or people who have sensitive skin tendency should be very conscious when there are fires around them and follow instructions about staying inside when those recommendations are being made to the general population,” Eichenfield says.

When you do go outside, Wei says to opt for long sleeves and pants which will provide a layer of fabric protection to keep out some of the contaminants. It’s also important to bathe regularly to remove toxins from the skin. Wearing moisturizers can also protect the skin barrier. Both people with a history of eczema and those without should be cognizant of new rashes or itchiness.

“I would encourage people to make an appointment to see a dermatologist if they have a concern with regards to itch or worsening of their atopic dermatitis,” Wei says “If they don't have that diagnosis, and they're experiencing symptoms, definitely seeing a dermatologist will be helpful.”