Relationship between air pollution levels in Madrid and the natural history of idiopathic pulmonary fibrosis: severity and mortality.

Objective: We aimed to assess the relationship between major air pollutants and the natural history and mortality of idiopathic pulmonary fibrosis (IPF).

Methods: We conducted a retrospective cohort study from 2013 to 2019 among 52 patients with IPF from the pneumology department of a tertiary hospital. According to their geocoded residential address, each patient was assigned a mean concentration of carbon monoxide (CO), nitrogen dioxide, particulate matter 2.5 and 10, ozone, and sulfur dioxide, as measured at a single surveillance station in central Madrid, Spain. We analyzed forced vital capacity (FVC), CO diffusing capacity, 6-minute walking test, degree of dyspnea, radiologic pattern, and signs of pulmonary hypertension in all patients.

Results: Patients' mean age was 66 ± 10 years, and 79% were men. The mean predicted FVC was 78.9 ± 0.5%. Forty-two patients met the criteria for severe disease, and 18 patients died. Mortality was significantly associated with increased CO exposure (for each 0.1 mg/m increase: odds ratio 2.45, 95% confidence interval 1.39-4.56). We observed no association between any of the other investigated contaminants and IPF mortality or severity.

Conclusions: Air pollution, specifically that caused by carbon monoxide, can increase mortality in patients with IPF.