Greater ozone exposure is associated with greater severity of interstitial lung disease (ILD) in patients with systemic sclerosis, according to a study published in Respiratory Research. 

There is broad consensus that air pollution contributes, at least in part, to the pathophysiology of systemic sclerosis, a disease characterized by autoimmune features and endothelial/fibroblast dysfunction. Air pollution, in particular, has attracted academic interest in recent years; for example, a study shows that benzene exposure positively correlates with skin score, but inversely correlates with the diffusion of carbon monoxide in the lung. 

The authors of the study sought to assess in greater detail the relationship between ILD in systemic sclerosis and air pollutants; specifically, particulate matter up to 10 or 2.5 µm in diameter (PM10 and PM2.5), nitrogen dioxide (NO2), and oxide. The research team also assessed whether air pollution is associated with greater disease severity upon diagnosis and whether this influence carries forward, impacting disease progression as well. 

The authors accessed data from the French hospital discharge database, with a search period between January 1, 2006, and December 31, 2019. Two French centers were selected for the study. Patients must have been diagnosed with ILD associated with systemic sclerosis during the study period to be considered candidates for the study. 

Read more about systemic sclerosis etiology 

One hundred eighty-one patients matching the inclusion criteria were identified. According to the Goh staging algorithm, 29% patients had extensive ILD upon diagnosis. Specifically, ozone exposure was heavily linked to extensive ILD at diagnosis. In addition, researchers found that ozone was the only air pollutant studied that was associated with severe ILD upon diagnosis, as well as progression at 24 months. 

“The identification of O3 exposure as a preventable risk factor could lead to avoidance measures, particularly during periods of high O3 levels in warm weather,” the authors wrote. 


Roeser A, Sese L, Chassagnon G, et al. The association between air pollution and the severity at diagnosis and progression of systemic sclerosis-associated interstitial lung disease: results from the retrospective ScleroPol studyRespir Res. Published online June 8, 2023. doi:10.1186/s12931-023-02463-w