Figure 5
From: PM2.5 in Beijing – temporal pattern and its association with influenza
The association between monthly PM 2.5 (μg/m 3 ) and reported influenza cases (in five urban districts) from 2008 to 2011 in Beijing. Top – monthly PM2.5 and reported influenza cases. Bottom: Wavelet coherence between the standardized PM2.5 measurements and reported influenza cases in Beijing. The 5% significance level against red noise is shown as a thick contour. The relative phase relationship is shown as arrows, suggesting that PM2.5 leads influenza by about 90o pointing down, equivalent to 1-2 months delay in occurrence.