大城市阴霾天气的频频出现，引起社会对其罪魁祸首——细颗粒物即PM2.5的广泛关注。PM2.5 对健康的影响成为人们普遍担忧的问题。本文综述了PM2.5与呼吸系统疾病的流行病学研究进展。结果显示，短期暴露于较高浓度的PM2.5与哮喘急诊就诊率、慢性阻塞性肺病（COPD）患者急性加重住院率、肺炎急诊住院率的上升及COPD日死亡风险的增加均有关；长期暴露于较高浓度PM2.5与肺癌及肺炎死亡风险增加、肺腺癌和哮喘发病风险增加有关。上述研究结果大部分来自西方国家，提示了我国有效控制PM2.5浓度及开展更多关于PM2.5的流行病学研究的必要性和紧迫性。

The frequent occurrence of fog and haze weather in big cities of China has raised wide attention of the public to its main cause—fine particulate matters, namely, PM2.5. It has been a common concern of the public that how PM2.5 would affect people’s health. This review summarizes the latest epidemiological findings of the effect of PM2.5 on respiratory diseases. Epidemiological studies have shown that short-term exposure to relatively higher concentration of PM2.5 is positively associated with the increased risk of emergency department visits of patients with asthma, with the risk of hospital admissions for patients with chronic obstructive pulmonary disease (COPD) and pneumonia, and with daily mortality in patients with COPD. Long-term exposure of relatively higher concentration of PM2.5 is positively associated with the increased risk of lung cancer mortality and pneumonia mortality, and with the increased risk of lung adenocarcinoma incidence and asthma incidence. These results, most from western countries, suggest the urgent need to reduce PM2.5 concentration, as well as to conduct vigorous local epidemiological studies on PM2.5 in China.