Long-term exposure to air pollution linked to heightened autoimmune disease risk

Long term exposure to air pollution is linked to a heightened risk of autoimmune disease, finds new research.

The study found environmental air pollution from vehicle exhausts and industrial output can trigger adaptive immunity – whereby the body reacts to a specific disease-causing entity – but sometimes this adaptive response misfired, prompting systemic inflammation, tissue damage, and ultimately autoimmune disease.

The research, published online in RMD Open, found the risk is especially high for developing certain autoimmune conditions including rheumatoid arthritis, connective tissue and inflammatory bowel diseases.

The incidence and prevalence of autoimmune diseases have steadily increased over the past decade, but the reasons for this are not yet clear.

The researchers mined the national Italian fracture risk database, tracking diagnoses of autoimmune diseases and linking participants to the nearest air quality monitoring system run by the Italian Institute of Environment Protection and Research.

They found exposure to PM2.5 was not associated with a heightened risk of an autoimmune disease diagnosis, but PM10 was associated with a 7% heightened risk for every 10µg/m3 increase in levels, after accounting for potentially influential factors.

Long term exposure to PM10 above 30 µg/m3 and to PM2.5 above 20 µg/m3 were associated with, respectively, a 12% and 13% higher risk of autoimmune disease.

Long term exposure to PM10 was specifically associated with a heightened risk of rheumatoid arthritis, while long term exposure to PM2.5 was associated with a heightened risk of rheumatoid arthritis, connective tissue diseases and inflammatory bowel diseases.

Overall, long term exposure to traffic and industrial air pollutants was associated with an approximately 40% higher risk of rheumatoid arthritis, a 20% higher risk of inflammatory bowel disease, and a 15% higher risk of connective tissue diseases.

Although the study was observational so cannot establish cause, air pollution has previously been linked to immune system abnormalities, and smoking – which shares some toxins with fossil fuel emissions – is a predisposing factor for rheumatoid arthritis.

Photo by Towfiqu barbhuiya