Association between acute exacerbation of chronic obstructive pulmonary disease and short-term exposure to ambient air pollutants in France

Abstract

Background: Ambient air pollution is recognized as a major risk factor for chronic obstructive pulmonary disease (COPD) which is the third leading cause of death worldwide. We examined whether variations in daily outdoor air pollutants levels were associated with excess hospital emergency room visits (ERV) for acute exacerbation of COPD (AECOPD).

Methods: This two-center ecological cohort study was conducted in Amiens, France. We collected all consecutive ERV for AECOPD throughout 2017 and developed single pollutant models to assess the association between AECOPD and nitrogen dioxide (NO₂), ozone (O₃), or particulate matter (PM_2.5 and PM₁₀) levels, while adjusting for temperature, hygrometry, influenza circulation and pollen allergy risk. For a subgroup of patients, we also applied geographical modeling to analyze annual exposure to outdoor air pollutants.

Results: We recorded 240 ERV among 168 COPD patients in 2017 and identified 9 peaks of ERV. There was a statistically significant positive correlation between the daily ERV for AECOPD and the daily average concentrations of PM_2.5 (RR = 1.06 (95%CI = [1.00-1.11]), p = 0.049), but no correlation with NO₂, O₃ or PM₁₀ (p = 0.073, p = 0.114 and p = 0.119, respectively). Our geographical modeling study revealed that long-term exposure to any of the four outdoor air pollutants was not associated with more frequent AECOPD.

Conclusion: Even though the pollution levels measured generally remained below or near the 2021 short-term air quality guidelines issued by the World Health Organization, significant aggregate-level associations were found between severe AECOPD leading to ERV and daily concentrations of PM_2.5.

Clinical trial registration: NCT03079661.

Keywords: Chronic obstructive pulmonary disease; Morbidity; Nitrogen dioxide; Ozone; Particulate matter.

Fig. 1

Concentrations of the different pollutants recorded during 2017 and peaks of emergency room visits for acute exacerbation of COPD. Panels A, B, C, and D show data for O₃, NO₂, PM_2.5, and PM₁₀, respectively. Peaks in emergency room visits are indicated by blue shading. The influenza epidemic period is indicated by the violet arrows, and periods with a high pollen allergy risk index are marked with brown arrows

Fig. 2

Modeling map showing the mean annual concentration of NO2 in the study area, along with the localization of subjects’ residences Subjects’ residences are indicated by small circles. The black arrow in the color scale represents the French long-term quality objective for NO2 (40 µg/m³)