Journal Article

Short-term air pollution exposure and exacerbation events in mild to moderate COPD: a case-crossover study within the CanCOLD cohort

Hernandez, Paul, O'Donnell, Denis E, Marciniuk, Darcy, Bourbeau, Jean, Doiron, Dany, Benedetti, Andrea, Chapman, Kenneth, Sin, Don D, Walker, Brandie L, Ross, Bryan A, Maltais, François, Aaron, Shawn D, Tan, Wan

2023

Overview

BackgroundInfections are considered as leading causes of acute exacerbations of chronic obstructive pulmonary disease (COPD). Non-infectious risk factors such as short-term air pollution exposure may play a clinically important role. We sought to estimate the relationship between short-term air pollutant exposure and exacerbations in Canadian adults living with mild to moderate COPD.MethodsIn this case-crossover study, exacerbations (‘symptom based’: ≥48 hours of dyspnoea/sputum volume/purulence; ‘event based’: ‘symptom based’ plus requiring antibiotics/corticosteroids or healthcare use) were collected prospectively from 449 participants with spirometry-confirmed COPD within the Canadian Cohort Obstructive Lung Disease. Daily nitrogen dioxide (NO2), fine particulate matter (PM2.5), ground-level ozone (O3), composite of NO2 and O3 (Ox), mean temperature and relative humidity estimates were obtained from national databases. Time-stratified sampling of hazard and control periods on day ‘0’ (day-of-event) and Lags (‘−1’ to ‘−6’) were compared by fitting generalised estimating equation models. All data were dichotomised into ‘warm’ (May–October) and ‘cool’ (November–April) seasons. ORs and 95% CIs were estimated per IQR increase in pollutant concentrations.ResultsIncreased warm season ambient concentration of NO2 was associated with symptom-based exacerbations on Lag−3 (1.14 (1.01 to 1.29), per IQR), and increased cool season ambient PM2.5 was associated with symptom-based exacerbations on Lag−1 (1.11 (1.03 to 1.20), per IQR). There was a negative association between warm season ambient O3 and symptom-based events on Lag−3 (0.73 (0.52 to 1.00), per IQR).ConclusionsShort-term ambient NO2 and PM2.5 exposure were associated with increased odds of exacerbations in Canadians with mild to moderate COPD, further heightening the awareness of non-infectious triggers of COPD exacerbations.

• Publisher: BMJ Publishing Group Ltd and British Thoracic Society,BMJ Publishing Group LTD
• Subject: Air pollution / Airborne particulates / Airway management / Antibiotics / Chronic obstructive pulmonary disease / Cities / Clinical epidemiology / COPD epidemiology / COPD exacerbations / COPD exacerbations mechanisms / Gender / Lung diseases / Nitrogen dioxide / Outdoor air quality / Pollutants / Population / Spirometry / Temperature