Daijiworld Media Network - New Delhi

New Delhi, Jun 23: Long-term exposure to particulate matter (PM) pollution may increase the risk of developing alopecia areata (AA), an autoimmune condition that causes patchy hair loss, according to a large nationwide epidemiological study.

Researchers examined the link between prolonged exposure to fine particulate matter (PM2.5) and coarse particulate matter (PM10) and new cases of AA by analysing annual pollution exposure data along with national health screening records of individuals tracked between 2006 and 2022.

Incident cases of alopecia areata were identified through healthcare records, with researchers considering patients who had at least three outpatient claims carrying relevant diagnostic codes within a year.

The study found that higher exposure to both PM2.5 and PM10 was associated with a significant rise in AA risk. A 10 μg/m³ increase in PM2.5 exposure was linked to a 45% higher risk of developing AA, while the same increase in PM10 exposure was associated with a 32% higher risk.

The strongest association was observed in alopecia universalis, the most severe form of the condition, which causes extensive hair loss from the scalp and body. Researchers found that increased PM2.5 exposure more than doubled the risk of alopecia universalis, while PM10 exposure raised the risk by 82%.

To understand the possible biological mechanism, researchers conducted laboratory experiments using human hair follicle outer root sheath cells exposed to PM10-like particles for 24 hours.

The exposure triggered oxidative stress and inflammatory responses, increasing levels of immune-related molecules including IL-1β, IL-6, IL-8 and IL-15RA. Pollution exposure also activated inflammatory pathways involving p38 and STAT3, which may contribute to damage linked to hair follicle disorders.

The researchers suggested that air pollution could be a modifiable environmental factor contributing to autoimmune hair loss by promoting inflammation and oxidative stress in hair follicle cells.

The findings highlight the need for reducing particulate matter exposure as part of wider public health measures. However, researchers noted that further studies are required to establish a direct cause-and-effect relationship and determine whether lowering pollution exposure can reduce the risk of alopecia areata.