Background Infections 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. Methods In 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. Results Increased 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). Conclusions Short-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. Data are available upon reasonable request.

中文翻译：

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轻度至中度 COPD 的短期空气污染暴露和恶化事件：CanCOLD 队列中的病例交叉研究

背景 感染被认为是慢性阻塞性肺病（COPD）急性加重的主要原因。非传染性危险因素，例如短期空气污染暴露，可能在临床上发挥重要作用。我们试图估计患有轻度至中度慢性阻塞性肺病的加拿大成年人短期空气污染物暴露与病情加重之间的关系。方法 在这项病例交叉研究中，前瞻性地从 449 名参与者中收集了病情加重情况（“基于症状”：≥48 小时的呼吸困难/痰量/化脓；“基于事件”：“基于症状”加上需要抗生素/皮质类固醇或医疗保健使用）加拿大阻塞性肺病队列中经肺活量测定证实患有慢性阻塞性肺病（COPD）的患者。每日二氧化氮 (NO2)、细颗粒物 (PM2.5)、地面臭氧 (O3)、NO2 和 O3 复合物 (Ox)、平均温度和相对湿度估计值均从国家数据库获得。通过拟合广义估计方程模型，对“0”天（事件日）和滞后期（“−1”至“−6”）的危害和控制期的时间分层采样进行比较。所有数据均分为“温暖”（5 月至 10 月）和“凉爽”（11 月至 4 月）季节。OR 和 95% CI 是根据污染物浓度的 IQR 增加来估算的。结果 暖季环境 NO2 浓度增加与 Lag−3 上基于症状的恶化相关（1.14（1.01 至 1.29），每个 IQR），而冷季环境 PM2.5 增加与 Lag−1 上基于症状的恶化相关（1.11（1.03 至 1.20），每个 IQR）。暖季环境 O3 与 Lag−3 上基于症状的事件之间存在负相关（每个 IQR 为 0.73（0.52 至 1.00））。结论 短期环境 NO2 和 PM2.5 暴露与患有轻度至中度 COPD 的加拿大人病情加重几率增加相关，进一步提高了对 COPD 病情加重的非感染性触发因素的认识。数据可根据合理要求提供。