THURSDAY, Aug. 6, 2026 (HealthDay News) -- Exposure to air pollution, especially fine particulate matter (PM2.5), is associated with an increased risk for rheumatoid arthritis (RA) disease activity and flare risk, according to a study published online Aug. 5 in the Annals of Rheumatic Diseases.
Sung Cheol Jung, from the Seoul National University College of Medicine in South Korea, and colleagues examined the associations of air pollution with disease activity and flare rate in a prospective cohort study involving patients with RA treated between January 2021 and December 2024. Monthly mean concentrations of six air pollutants (sulfur dioxide, nitrogen dioxide, ozone, carbon monoxide, PM10, and PM2.5) were used to estimate air pollution exposure. At each outpatient visit, disease activity and flares were recorded longitudinally.
The analyses included 12,583 outpatient visits from 1,070 patients. The researchers found that among the six pollutants, PM2.5 was significantly associated with increased flare risk (adjusted odds ratio, 1.113) and with a higher Disease Activity Score based on 28 joints (DAS28) with C-reactive protein (CRP), Clinical Disease Activity Index, 28-tender joint count, and 28-swollen joint count. Women and nonsmokers had a more pronounced association between PM2.5 and DAS28-CRP. Prolonged cumulative exposure to PM2.5 over more than two weeks was associated with increased RA flare risk in the case-crossover sensitivity analysis.
"Our study has important implications for public health policy making," lead author Eun Bong Lee, M.D., Ph.D., also from the Seoul National University College of Medicine, said in a statement. "While further studies are warranted to determine whether improving air quality can reduce disease activity in RA patients, we would recommend these patients avoid prolonged exposure to poor air quality, particularly high PM2.5 levels."
One author disclosed ties to the biopharmaceutical industry.
