Analysis: Air Pollution Linked with Elevated Disease Activity in Bullous Pemphigoid

New retrospective research indicates a relationship between ambient air pollution and increased disease activity in patients with bullous pemphigoid (BP), compared to those with pemphigus.

Researchers analyzed 617 clinic visits from 115 BP patients and 1,237 visits from 152 pemphigus patients at a Southeastern U.S. autoimmune blistering disease clinic between 2014 and 2020. The researchers looked at correlations between air quality metrics and disease severity drawn from disease activity indices and publicly available U.S. EPA environmental data.

The Bullous Pemphigoid Disease Area Index (BPDAI) total activity score correlated with particulate matter ≤2.5 μm (PM2.5), sulphur dioxide (SO₂), and overall air quality index (AQI). Ozone was negatively correlated with BPDAI pruritus scores (P = .033). Carbon monoxide showed a weak negative association with Pemphigus Disease Area Index (PDAI) activity scores (P = .042).

“These observations suggest that air pollution may contribute to disease activity in BP to a greater extent than in pemphigus,” the authors wrote. “This corroborates prior findings that high concentrations of particulate matter is associated with disease severity in T helper 2 (Th2)–mediated inflammatory skin diseases.”

Study limitations include its retrospective design and inability to control for confounding factors such as allergic comorbidities or indoor pollutant exposure. 

“Future studies should be aimed at identifying potential mechanisms for this association,” the authors wrote. “Determining which environmental factors are the most important, particularly for disease flares, and other factors that contribute to this association.”

Source: Feldman R, Cole E. JID Innovations. 2025. doi:10.1016/j.xjidi.2024.100334