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. 2025 Jul;77(7):808-816.
doi: 10.1002/art.43113. Epub 2025 Feb 3.

Associations of Fire Smoke and Other Pollutants With Incident Rheumatoid Arthritis and Rheumatoid Arthritis-Associated Interstitial Lung Disease

Vanessa L Kronzer  1 , Yangyuna Yang  2 , Punyasha Roul  2 , James L Crooks  3 , Cynthia S Crowson  1 , John M Davis 3rd  1 , Jeffrey A Sparks  4 , Jeffrey R Pierce  5 , Katelyn O'Dell  6 , Brian C Sauer  7 , Grant W Cannon  7 , Joshua F Baker  8 , Ted R Mikuls  2 , Bryant R England  2
Affiliations

Associations of Fire Smoke and Other Pollutants With Incident Rheumatoid Arthritis and Rheumatoid Arthritis-Associated Interstitial Lung Disease

Vanessa L Kronzer et al. Arthritis Rheumatol. 2025 Jul.

Abstract

Objective: The aim of this study was to determine whether pollutants such as fire smoke-related particulate matter <2.5 μm (PM2.5) are associated with incident rheumatoid arthritis (RA) and RA-associated interstitial lung disease (RA-ILD).

Methods: This patient-control study used Veterans Affairs (VA) data from October 1, 2009, to December 31, 2018. We identified patients with incident RA and RA-ILD using validated algorithms, matching each patient to ≤10 controls on age, sex, and VA enrollment year. We obtained pollutants including fire smoke PM2.5, carbon monoxide, nitrogen oxides (NOx), ozone, overall PM2.5, PM10, and sulfur dioxide (SO2) at least one year before the index date. We fit conditional logistic regression models to estimate adjusted odds ratios (aORs) with 95% confidence intervals (CIs) for incident RA and RA-ILD, adjusted for confounders.

Results: We identified 9,701 patients with incident RA (mean age 65 years, 86% male), including 531 patients with RA-ILD (mean age 69 years, 91% male), and 68,852 matched controls. Fire smoke PM2.5 was not associated with RA (aOR 1.07, 95% CI 0.92-1.23) but was associated with RA-ILD (aOR 1.98, 95% CI 1.08-3.62, per 1 μg/m3). Increased levels of NOx were associated with RA (aOR 1.16, 95% CI 1.06-1.27, highest vs lowest quartile). The highest quartiles of ozone (aOR 1.19, 95% CI 1.06-1.34) and PM10 (aOR 1.25, 95% CI 1.10-1.43) were associated with seronegative RA. Carbon monoxide, overall PM2.5, and SO2 were not, or negatively, associated with RA and RA-ILD.

Conclusion: Increased fire smoke PM2.5 was associated with RA-ILD, whereas NOx, ozone, and PM10 were associated with RA risk. Thus, air pollution may increase the risk of RA and RA-ILD.

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Figures

Figure 1
Figure 1
Forest plot depicting associations of fire smoke PM2.5 with risk of RA by exposure time period. Models are per 1‐μg/m3 increase in PM2.5 and adjusted for age, sex, enrollment, duration of pollutant exposure data, race and ethnicity, body mass index, and smoking status. PM2.5, particulate matter <2.5 μm; RA, rheumatoid arthritis.
See this image and copyright information in PMC

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