Association Between Short-term Ambient Air Pollution and Psoriasis: A Time-Stratified Case-Crossover Study

This time-stratified case-crossover study evaluated the association between short-term exposure to ambient air pollution and psoriasis. A total of 107 462 psoriasis cases between 2002 and 2016 were retrieved from Taiwan's National Health Insurance Research Database. Conditional logistic regression was used to estimate the association between air pollutants (O₃, CO, NO₂, SO₂, PM_2.5, and PM₁₀) and psoriasis with each interquartile range (IQR) increase. Consistent associations for psoriasis for each IQR increase in NO₂ and CO exposure were noted at lag 0 both in single-pollutant and multiple-pollutant model. Exposure on lag 0 had the highest odds ratio (OR), decreasing consecutively from lag 1 to lag 3. Both NO₂ and CO had a stronger influence among men, older patients (>60 years old), and patients with chronic disease. Short-term NO₂ and CO exposure was associated with psoriasis. This link might provide insights into how air pollution, at least in part, affects the epidemiology and pathogenesis of psoriasis.