Analysis of SO₂ Pollution Changes of Beijing-Tianjin-Hebei Region over China Based on OMI Observations from 2006 to 2017

Figure 16

Monthly average SO₂ of August (a), September (b), and November (c) from 2006 to 2017. The black solid squares show relative changes based on 2006. The error bars express standard deviation. The red solid squares represent the months when events occur.

(a)

(b)

(c)