Air pollution might play a role in people's risk for developing autoimmune diseases like lupus and rheumatoid arthritis, a new study says.
People exposed to particle air pollution had higher levels of anti-nuclear antibodies, a characteristic marker of autoimmune rheumatic diseases, researchers recently reported in the journal Rheumatology.
"These results point us in a new direction for understanding how air pollution might trigger immune system changes that are associated with autoimmune disease," senior researcher Dr. Sasha Bernatsky, a professor of medicine at McGill University in Canada, said in a news release.
For the study, researchers collected blood samples from more than 3,500 people living in Canada's Ontario region, looking at their levels of anti-nuclear antibodies.
Anti-nuclear antibodies are produced by the immune system as part of an autoimmune disease. These antibodies mistakenly target the body's own cells and tissues.
The team compared those blood test results to people's average exposure to particle pollution, based on air pollution tracking data for their home address.
People with the highest levels of exposure to air pollution were 46% to 54% more likely to have high levels of anti-nuclear antibodies, the study found.
Fine particle pollution involves particles that are 2.5 microns wide or smaller, according to the U.S. Environmental Protection Agency. By comparison, a human hair is 50 to 70 microns wide.
"These fine particles in air pollution are small enough to reach the bloodstream, potentially affecting the whole body," Bernatsky said.
She stressed that such pollution is not just a problem for big cities.
"Air pollution is often seen as an urban problem caused by traffic, but rural and suburban areas experience poor air quality too," Bernatsky said, pointing to wildfires that choke the sky with smoke.
The results underscore why standards to reduce air pollution are important, she concluded.
"Even though air quality is overall better in Canada than in many other countries, research suggests there is no safe level, which is why Canadian policymakers need research like ours," Bernatsky said.
More information
Johns Hopkins has more on autoimmune diseases.
SOURCES: McGill University, news release, Dec. 15, 2025; Rheumatology, Oct. 22, 2025