Data from Canada's most populous province add to emerging evidence that air pollution risks go beyond lung and heart health
SOURCE: McGill University
December 18, 2025
A new study in the journal Rheumatology has linked air pollution exposure to immune-system changes that often precede the onset of autoimmune diseases. McGill University researchers analyzing data from the province of Ontario, Canada, found that fine particles in air pollution are associated with higher levels of a biomarker linked with autoimmune diseases, such as systemic lupus.
"These results point us in a new direction for understanding how air pollution might trigger immune system changes that are associated with autoimmune disease," said Sasha Bernatsky, MD, PhD, Senior Scientist in the Infectious Diseases and Immunity in Global Health Program at the Research Institute of the McGill University Health Centre (The Institute). "We know some genetic factors play a role in autoimmune disease, but they don't tell the whole story."
More broadly, the findings add to mounting evidence that air pollution affects more than heart and lung health.
"These fine particles in air pollution are small enough to reach the bloodstream, potentially affecting the whole body," she added.
Comparing pollution levels across postal codes in Ontario
The researchers analyzed blood samples from over 3,500 people enrolled in CanPath, a national registry that has enrolled over 400,000 Canadians from Quebec, Ontario and other provinces.
They found that high levels of anti-nuclear antibodies (ANA) were more likely to come from people who lived in postal codes with higher levels of fine particulate matter (PM2.5) air pollution.
Bernatsky, who is also a James McGill Professor of Medicine in the Division of Rheumatology at McGill University, stressed that air pollution is not only an urban problem.
"Air pollution is often seen as an urban problem caused by traffic, but rural and suburban areas experience poor air quality too," Bernatsky said, citing wildfire smoke as a key potential contributor.
'No safe level' of PM2.5
Canada sets national standards for PM2.5, and awareness is growing among policymakers about the need to limit exposure, the researchers note. "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," said Bernatsky.
However, not every Canadian is equally vulnerable. Lower-income communities are sometimes closer to industrial emitters or major roadways, and autoimmune diseases like lupus disproportionately affect women and non-white populations, including Indigenous peoples.
In a 2017 Quebec study, also led by Bernatsky, living close to industrial sources of fine particles was found to raise blood markers linked to rheumatoid arthritis. The team's next study will turn to data in British Columbia.
About the study
"Fine particulate matter air pollution and anti-nuclear antibodies" by Naizhuo Zhao, Audrey Smargiassi, Hong Chen, May Y Choi, Marvin J Fritzler, Zahi Touma, J Antonio Aviña-Zubieta, and Sasha Bernatsky, was published in Rheumatology. The study was supported by the Canadian Institutes of Health Research. Methodologic oversight was provided by co-author Dr. Audrey Smargiassi, University of Montreal.
Contact information for media
Keila DePape
Media Relations, McGill University
keila.depape@mcgill.ca