Air Pollution and Disease Flares in RA
Across 12,583 outpatient visits in 1,070 patients with established RA in Seoul, higher fine-particle air pollution (PM2.5) was associated with more flares and with higher disease activity, and a case-crossover analysis suggested the effect builds over about two weeks of exposure rather than from a single bad day. The associations are real in the data but small, and the flare finding appears only after adjustment.