If you live in a city or near a busy road, it might not just be your lungs bearing the brunt of air pollution – your skin could be suffering too. A recent study has found a significant link between high levels of fine particulate matter (PM2.5) and incidence of eczema – a chronic inflammatory skin condition marked by itching, redness and discomfort.
The research, conducted on more than 280,000 people across the US, revealed that people exposed to higher concentrations of PM2.5 were more than twice as likely to have eczema compared to those in less polluted areas.
This study sheds new light on how our external environment may affect our skin health and raises questions about how we can protect ourselves as pollution levels climb.
Particulate matter and skin health
PM2.5 is shorthand for particulate matter that is less than 2.5 micrometres in diameter. These particles are so small that you’d need a microscope to see them – yet they have significant health risks.
Emitted from sources such as cars, industrial sites and even wildfire smoke, these tiny particles contain harmful chemicals – including polycyclic aromatic hydrocarbons (PAHs). These chemicals are carcinogenic and been linked to respiratory, cardiovascular and developmental health issues.
Although we have a good understanding of the significant effect PM2.5 has on the health of our lungs, scientists are only just beginning to uncover all the ways these particles affect the health of our skin.
This latest study provides yet more evidence of the effects that pollution appears to have on our skin health. The study found that participants with eczema had been exposed to slightly higher than average PM2.5 levels than those without the condition. This difference was linked to a significantly higher incidence of eczema in those exposed to high levels of air pollution. This was true even after the researchers adjusted their analysis to account for other factors that may have affected a person’s risk of eczema.
While this study can’t directly prove that air pollution caused or worsened eczema in these participants, numerous studies have pinpointed the ways in which air pollution affects the skin. This may help to explain the link the study found.
Research shows the tiny size of PM2.5 allows it to infiltrate the skin barrier – the body’s first line of defence. This means it can penetrate skin cells directly, reaching deeper layers where it can cause even more damage to cells. This disruption can impair the skin’s natural defences, leading to increased inflammation and skin sensitivity. For people already struggling with eczema, this intrusion is like pouring salt on an open wound.
Other studies may point to reasons why air pollution could trigger or worsen eczema in the first place.
It appears that PM2.5 may interact with our skin’s immune responses in ways we are only beginning to understand. When these particles reach the skin, they bind to a receptor called the aryl hydrocarbon receptor (AhR), a protein known to mediate how cells respond to environmental toxins. This interaction can ignite a cascade of immune responses – essentially triggering an inflammatory response in the skin. For someone prone to eczema, these immune responses can result in the itching, swelling and redness that define the condition.
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Previous studies have also found that people with eczema have an impaired skin barrier, making them more susceptible to absorbing external irritants such as pollutants. In addition, research supports the idea that PM2.5 might exacerbate eczema by further compromising the skin barrier.
Health risks
These findings couldn’t come at a more critical time. Globally, air pollution levels are rising – and urban populations are being exposed to ever-higher amounts of PM2.5. According to the World Health Organization, around 90% of people globally breathe air with unsafe levels of pollutants. Already vulnerable groups – including children, the elderly and those with pre-existing skin conditions – could be most at risk of developing eczema.
It’s becoming increasingly clear that pollution affects health in multifaceted ways, beyond just respiratory issues. Our skin, the body’s largest organ, is also at risk. Recognising these connections could guide policies to enforce stricter air quality controls, protecting not only the air we breathe but also the skin we rely on for protection.
On a personal level, reducing direct exposure to polluted air can be beneficial – especially for those prone to eczema. Some ways of doing this include staying indoors on high-pollution days, using air purifiers and covering exposed skin.
There’s also promise in treatments targeting the AhR pathway. Current research into treatments that activate “good” pathways of AhR in the skin shows potential for managing eczema symptoms – especially for those exposed to elevated PM2.5 levels. Tapinarof, a cream investigators are currently testing, could potentially counterbalance the harmful effect of pollution on the skin if proven successful. This could provide hope to eczema sufferers.
This emerging understanding on the hidden impacts of air pollution suggests that it could be a hidden culprit in the global rise of skin issues such as eczema.
The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.
