Air pollution—particularly exposure to fine particulate matter (PM2.5)—is associated with increased disease activity and a higher risk of flare-ups in people with rheumatoid arthritis (RA), according to a new study by researchers in South Korea. The findings were published in the journal Annals of the Rheumatic Diseases.
Rheumatoid arthritis is a chronic autoimmune disease in which the immune system mistakenly attacks the joints, causing inflammation and progressive damage. The condition can also affect other organs and is often accompanied by systemic symptoms.
Researchers from Seoul National University followed 1,070 patients with rheumatoid arthritis over a four-year period, analyzing data from more than 12,500 clinical visits. They compared patients' disease activity with levels of six major air pollutants, including sulfur dioxide, nitrogen dioxide, ozone, carbon monoxide, and particulate matter (PM10 and PM2.5).
The strongest association was observed with PM2.5—ultrafine particles measuring less than 2.5 micrometers in diameter that are commonly found in smoke, soot, and dust. Prolonged exposure to elevated PM2.5 levels, particularly for more than two consecutive weeks, was linked to increased disease activity and a greater likelihood of rheumatoid arthritis flare-ups.
The researchers explain that PM2.5 particles are small enough to pass from the lungs into the bloodstream, allowing them to circulate throughout the body. Once there, they can trigger the production of reactive oxygen species, leading to cellular stress and inflammatory responses.
According to the study authors, the findings suggest that air quality may be an important environmental factor influencing the course of rheumatoid arthritis.
They recommend that people living with rheumatoid arthritis minimize prolonged exposure to heavily polluted environments whenever possible.
The researchers also caution that the study was conducted exclusively in patients from South Korea. Additional research involving other countries and more diverse populations will be needed to confirm whether the findings apply more broadly.
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