A series of devastating forest fires occurred in June last year torn through the Canadian province of Quebec, releasing huge plumes of acrid smoke floating throughout North America. Two hundred miles away in Boston, dermatologist Shadi Kourosh noticed something strange. “We had an unusual spike in dermatology visits,” said Kourosh, director of community health in the department of dermatology at Massachusetts General Hospital and an assistant professor at Harvard Medical School.
Patients whose flare-ups of eczema or itchy skin would normally only be a problem in winter came to her clinic in mid-summer. Like New York, Detroit and other cities in the northern United States, Boston was experiencing above-average air pollution due to the wildfires, and Kourosh suspected this could be impacting people’s skin.
To prove this, her team collected five years of data from the U.S. Environmental Protection Agency on particulate matter and carbon monoxide levels in Boston, and linked it to anonymized patient records from Mass General Brigham Hospital, the largest hospital group in the world. Massachusetts.
She found it a link between air pollution levels and hospital visits for atopic dermatitis, the most common form of eczema. In June 2022, carbon monoxide levels in Boston were less than 0.2 parts per million, and the number of clinic visits for atopic dermatitis and eczema was less than 20. In June 2023, during the wildfires, carbon monoxide levels were three times higher. at 0.6 parts per million, and the number of dermatology visits had increased to 160.
It is not only acute events such as forest fires that can affect the skin; daily pollution from vehicles and industry also has an effect. In 2021, scientists in China found a clutch between higher baseline levels of air pollution and conditions such as eczema in children in Guangzhou.
“Many of these components of air pollution are irritating to the skin,” Kourosh explains. On contact, they can cause inflammation and cause the skin to age faster. “People with eczema have a weakened, more fragile skin barrier, which allows pollutants to penetrate deeper and activate the immune system,” she says. This leads to flare-ups and explains the spike in visits she noticed at her clinic.
Air pollution has been linked to a host of health problems, ranging from asthma and lung cancer to diabetes and obesity. In that context, focusing on the skin may seem trivial. But it is extremely important. More than 99 percent of the world’s population live in places where pollution levels exceed World Health Organization guidelines, and serious skin conditions such as atopic dermatitis can be intensely disabling. “Yes, it doesn’t kill anyone, but if you suffer seriously from it, you have a terrible quality of life,” says Carsten Flohr of the British Association of Dermatologists. “The sleep disorder, especially if you have eczema from a young age, is a form of torture. You can never establish the right body rhythm, and that has all kinds of other consequences: anxiety, depression, social withdrawal.”
What starts as a skin condition in childhood can quickly develop through what is known as the “atopic march”, to food allergies and asthma. It is thought that air pollution can make people more sensitive to other allergens by putting the immune system into a hyper-alert state. “It’s almost as if the air pollution ‘opens up’ the skin and makes contact between the skin’s immune system and the environment more likely,” says Flohr. “Air pollution is like a catalyst in a chemical reaction.”