Association between Air Quality Index and the risk of rosacea: a nationwide population-based cohort study

Air pollution is associated with several inflammatory skin disorders. However, the association between air quality and rosacea remains unclear. To investigate the association between the Air Quality Index (AQI) and incidence of rosacea. In total, 21 709 479 participants without rosacea before 2008 were recruited from the Taiwan National Health Insurance Research Database. The long-term average AQI value for each participant was acquired from the Taiwan Air Quality Monitoring System Network and calculated from 1 January 2008 until the diagnosis of rosacea, withdrawal from the National Health Insurance programme, or 31 December 2018. We observed a significant association between AQI and the incidence of rosacea, with each unit elevation in the AQI increasing the risk of rosacea by 5%. We then categorized participants equally into four groups by quantiles (Q) of AQI values, with mean AQI values of: Q1, 69.0 (SD 6.4); Q2, 79.0 (SD 2.3); Q3, 89.9 (SD 3.6); and Q4, 103.9 (SD 6.8). Compared with the Q1 group, the Q2, Q3 and Q4 cohorts exhibited 1.82-fold, 4.48-fold and 7.22-fold increased risk of rosacea, respectively. Additionally, exposure to particulate matter (PM)2.5 (airborne particulate matter with a diameter ≤ 2.5 μm), sulfur dioxide (SO2) and carbon monoxide increased the risk of rosacea, whereas exposure to PM10 (airborne PM with a diameter ≤ 10 μm) was associated with a lower risk. This study supported a significant dose-response relationship between AQI and the incidence of rosacea.