TOPLINE:

Long-term exposure to fine particulate matter (PM_2.5) and its components was associated with a risk of developing systemic autoimmune rheumatic diseases (SARDs).

METHODOLOGY:

• Researchers assembled a retrospective, population-based open cohort using the Québec Integrated Chronic Disease Surveillance System to assess the association of long-term exposure to PM_2.5 and its components with the risk for SARDs.
• The analysis included 7,482,397 residents (51% women) who had no prior history of SARDs and represented 98,039,305 person-years of follow-up.
• New cases of SARDs were identified using diagnostic codes related to physician claims or hospitalization, including codes for systemic lupus erythematosus, Sjögren disease, and others.
• Long-term exposure was estimated using annual concentrations of PM_2.5 obtained for residential postal codes, and proportions of each component were assessed using modeling results and calibration with ground observations.
• The components of PM_2.5 included ammonium, black carbon, mineral dust, sea salt, nitrate, sulfate, and organic matter.

TAKEAWAY:

• During follow-up, 55,267 incident SARD cases were recorded (5.6 per 10,000 person‐years). Among individuals with an incident SARD, most were women (70%) and older than 50 years, and many lived in urban regions.
• Exposure to PM_2.5 was linked to an increased risk for SARDs (adjusted hazard ratio [aHR], 1.036; 95% CI, 1.002-1.070 per one interquartile range [IQR] of PM_2.5 of 3.3 μg/m³).
• Exposure to PM_2.5 was also associated with an increased risk for SARDs among urban residents (aHR, 1.071; 95% CI, 1.032-1.111 per IQR increase of 2.1 μg/m³ in PM_2.5).

IN PRACTICE:

“This large population-based cohort study suggests that exposure to PM_2.5 and to the mixture of its components may be associated with the development of SARDs. It reinforces that effects of exposure to PM_2.5 may extend beyond the lungs, potentially to the immune system,” the authors wrote.

SOURCE:

The study was led by Mareva Geslin, MD candidate, Département de Santé Publique, Hôpital Pontchaillou, Centre Hospitalo-Universitaire, Rennes, France. It was published online on June 12, 2025, in Arthritis & Rheumatology.

LIMITATIONS:

Misclassification of PM_2.5 exposure may be possible particularly in rural areas where one postal code may cover extensive regions. Estimates based on postal codes may not reflect individual movement or exposures at work or during commutes. Residual confounding could not be ruled out owing to lack of data on factors such as smoking.

DISCLOSURES:

This study was supported by a grant from the Canadian Institutes of Health Research. The authors reported having no other conflicts of interest. 

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.