Long-term particulate matter exposure and risk of alopecia areata: a nationwide epidemiological study with preliminary <i>in vitro</i> evidence

This nationwide epidemiological study investigates the link between long-term exposure to particulate matter (PM) and the risk of developing alopecia areata (AA). The study analyzed data from individuals who underwent national health screenings from 2006 to 2022, finding that higher exposures to PM2.5 and PM10 were associated with an increased risk of AA, particularly the alopecia universalis subtype. The study also included preliminary in vitro experiments showing that PM10 exposure led to increased reactive oxygen species and inflammatory cytokine expression in human hair outer root sheath cells. The findings suggest that PM exposure is a modifiable environmental risk factor for AA, highlighting the importance of public health measures to reduce PM levels and potentially lower AA risk.