Association of particulate matter with autoimmune rheumatic diseases among adults in South Korea

OBJECTIVE: The primary objective of this study was to investigate adverse effects of ambient particulate matter of various sizes on the incidence of the prevalent autoimmune rheumatic diseases (AIRDs): RA, AS and SLE. METHODS: We investigated 230 034 participants in three metropolitan cities of South Korea from the National Health Insurance Service–National Sample Cohort (NHIS-NSC). Starting from January 2010, subjects were followed up until the first event of prevalent AIRDs, death, or December 2013. The 2008–2009 respective averages of particulate matter(2.5) (<2.5 μm) and particulate matter(coarse) (2.5 μm to 10 μm) were linked with participants’ administrative district codes. Adjusted hazard ratios (aHRs) and 95% CIs were estimated using Cox regression analysis in one- and two-pollutant models. RESULTS: Adjusted for age, sex, region, and household income, in the two-pollutant model, RA incidence was positively associated with the 10 μg/m³ increment of particulate matter(2.5) (aHR = 1.74, 95% CI: 1.06, 2.86), but not with particulate matter(coarse) (aHR = 1.27, 95% CI: 0.87, 1.85). In the one-pollutant model, the elevated incidence rate of RA was slightly attenuated (particulate matter(2.5) aHR = 1.61, 95% CI: 0.99, 2.61; particulate matter(coarse) aHR = 1.13, 95% CI: 0.80, 1.61), with marginal statistical significance for particulate matter(2.5). The RA incidence was also higher in the 4th quartile group of particulate matter(2.5) compared with the first quartile group (aHR = 1.83, 95% CI: 1.07, 3.11). Adverse effects from particulate matter were not found for AS or SLE in either the one- or two-pollutant models. CONCLUSION: The important components of particulate matter(10) associated with RA incidence were the fine fractions (particulate matter(2.5)); no positive association was found between particulate matter and AS or SLE.