Fig. 4From: Ambient air pollutants and hospital visits for pneumonia: a case-crossover study in Qingdao, ChinaOdds ratio and 95% confidence interval of hospital visits for pneumonia induced by principal component of atmospheric pollutants. Notes: ** P < 0.01; PC1: the first principal component; PC2: the second principal component; PC3: the third principal component; OR: odds ratio; CI: confidence intervalBack to article page