This prospective cohort study examined whether exposure to 6 air pollutants (SO₂, NO₂, ozone, CO, PM10, PM2.5) was associated with disease activity and flare risk in 1,070 RA patients across 12,583 outpatient visits at a South Korean tertiary center (January 2021–December 2024).
PM2.5 was the only pollutant significantly linked to flare risk (adjusted OR 1.113, 95% CI 1.017–1.218) and higher DAS28-CRP, CDAI, tender joint count, and swollen joint count; the effect was stronger in women and nonsmokers, and cumulative PM2.5 exposure >2 weeks was associated with increased flare risk in case-crossover analysis.
Single-center study in South Korea limits generalizability to other populations and pollution profiles; air pollution was estimated using regional monthly mean concentrations rather than individual-level monitoring; residual confounding from unmeasured lifestyle or environmental factors cannot be excluded.
Clinicians managing RA—especially in women and nonsmokers—should be aware that sustained PM2.5 exposure (>2 weeks) may trigger flares; advising patients to limit outdoor activity during high pollution periods is a reasonable, low-risk precaution while further evidence accumulates.
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