The association between air pollution and the severity at diagnosis and progression of systemic sclerosis-associated interstitial lung disease: results from the retrospective ScleroPol study

Objective To investigate the association of air pollution exposure with the severity of interstitial lung disease (ILD) at diagnosis and ILD progression among patients with systemic sclerosis (SSc)-associated ILD. Methods We conducted a retrospective two-center study of patients with SSc-associated ILD diagnosed between 2006 and 2019. Exposure to the air pollutants particulate matter of up to 10 and 2.5 µm in diameter (PM 10 , PM 2.5 ), nitrogen dioxide (NO 2 ), and ozone (O 3 ) was assessed at the geolocalization coordinates of the patients’ residential address. Logistic regression models were used to evaluate the association between air pollution and severity at diagnosis according to the Goh staging algorithm, and progression at 12 and 24 months. Results We included 181 patients, 80% of whom were women; 44% had diffuse cutaneous scleroderma, and 56% had anti-topoisomerase I antibodies. ILD was extensive, according to the Goh staging algorithm, in 29% of patients. O 3 exposure was associated with the presence of extensive ILD at diagnosis (adjusted OR: 1.12, 95% CI 1.05–1.21; p value = 0.002). At 12 and 24 months, progression was noted in 27/105 (26%) and 48/113 (43%) patients, respectively. O 3 exposure was associated with progression at 24 months (adjusted OR: 1.10, 95% CI 1.02–1.19; p value = 0.02). We found no association between exposure to other air pollutants and severity at diagnosis and progression. Conclusion Our findings suggest that high levels of O 3 exposure are associated with more severe SSc-associated ILD at diagnosis, and progression at 24 months.