Fig. 2From: Ambient air pollutants and hospital visits for pneumonia: a case-crossover study in Qingdao, ChinaTime-series plot of the concentration of air pollutants and the number of pneumonia hospital visits during the study. Notes: (a) the daily number of hospital visits for pneumonia in Qingdao; (b) the daily concentration of PM2.5; (c) the daily concentration of PM10; (d) the daily concentration of NO2; (e) the daily concentration of SO2Back to article page