Smoke from fires in Northern California lowers visibility of the Bay Bridge and San Francisco as viewed from Yerba Buena Island on October 2, 2020. File Photo by Terry Schmitt/UPI | License Photo
Long-term exposure to air pollution can wreak havoc on your lungs and heart, but new research suggests another vulnerability: It may increase your risk of rheumatoid arthritis and other autoimmune diseases.
For the study, the researchers analyzed health information on more than 81,000 people in Italy submitted by more than 3,500 doctors between June 2016 and November 2020. Most of the patients were women (92%), with an average age of 65.
More than 9,700 (12%) of the patients were diagnosed with an autoimmune disease -- including rheumatoid arthritis, lupus, inflammatory bowel diseases (such as ulcerative colitis), connective tissue diseases (such as osteoarthritis) and multiple sclerosis -- during the data collection period.
The researchers also examined readings from 617 air quality monitoring stations in 110 Italian provinces where the patients lived, with a focus on levels of particulate matter (PM10 and PM2.5) air pollution. Levels of 30 µg/m3 for PM10 and 20 µg/m3 for PM2.5 are the thresholds generally considered harmful to human health.
Average long-term exposure between 2013 and 2019 was 16 µg/m3 for PM2.5 and 25 µg/m3 for PM10, the findings showed.
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, according to the report.
Long-term exposure to PM10 was specifically associated with an increased risk of rheumatoid arthritis, while long-term exposure to PM2.5 was associated with an increased risk of rheumatoid arthritis, connective tissue diseases and inflammatory bowel diseases.
Long-term exposure to traffic and industrial air pollutants was associated with about a 40% higher risk of rheumatoid arthritis, a 20% higher risk of inflammatory bowel disease and a 15% higher risk of connective tissue diseases, Giovanni Adami, from the rheumatology unit at the University of Verona, and colleagues found.
Their report was published online Tuesday in the journal RMD Open.
This was an observational study, so it can't establish cause, the study authors noted in a journal news release. However, they pointed out that previous research has linked air pollution to immune system abnormalities, and that smoking -- which emits some of the same toxins found in fossil fuel emissions from vehicles and industry -- is a risk factor for rheumatoid arthritis.
There's more on autoimmune diseases at the U.S. National Institute of Arthritis and Musculoskeletal and Skin Diseases.
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