Relationship between exposure to air pollutants and development of systemic autoimmune rheumatic diseases: a nationwide population-based case–control study

Air pollutants are a heterogeneous mixture of gases and particles including particulate matter <2.5 µm in size (PM2.5), particulate matter <10 µm in size (PM10), nitrogen dioxide (NO2), carbon monoxide (CO), sulfur dioxide (SO2) and ozone (O3). Air pollutants have proinflammatory effects and are therefore among the environmental factors contributing to the generation of inflammation and autoimmunity. However, there is scanty data supporting the correlation between air pollution and systemic autoimmune rheumatic diseases (SARDs), which mainly include systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), systemic sclerosis and autoimmune myositis. We investigated the relationship between air pollutants exposure and SARDs in a nationwide population-based case–control study. From the National Health Insurance Research Database, we identified Chinese adult incident cases afflicted with one of SARDs as well as age-matched and gender-matched controls in a 1:4 ratio from 1 January 2012 to 31 December 2013 (table 1). Long-term residential exposure to air pollutants was estimated based on the monitoring data from Environmental Protection Agency in 2011. …