Association of Short-Term Wildfire Air Pollution Exposure and Health Care Usage: A Cross-Sectional Study Among Patients With Psoriasis From the Bay Area, United States

Background: Wildfire air pollution causes many adverse environmental and health effects, including adverse skin reactions. However, whether wildfire-associated air pollution and psoriasis disease activity are associated remains unknown. Objectives: To examine the association between short-term exposure to air pollution from wildfires and rates of psoriasis-related appointments and treatment prescriptions. Methods: This study is a cross-sectional time-series study. Air pollution exposure, clinic visits and treatment prescriptions data were collected for weeks around the 2018 California Camp Fire and equivalent weeks in 2015 and 2016 for adults with psoriasis. Results: We collected data on 5081 patients with 5185 psoriasis-related treatment prescriptions and 1387 clinic visits between October and December 2015, 2016, and 2018. A 10 μg/m³ fine particulate matter (PM) increase was significantly associated with a 5% (95% CI 2%–8%), 4% (2%–8%), and 3% (2%–8%) increased rate ratio of prescribed systemic psoriasis treatment in cumulative exposure–lag, respectively, for three, four, and 6 weeks before the prescriptions when adjusted for temperature and humidity. Conclusions: This study showed that short-term PM2.5 air pollution exposure from wildfires is associated with increased systemic psoriasis treatment prescriptions.