Fig. 1: PM2.5, gaseous precursors (SO2, NO2, NH3) and secondary inorganic ion (SNA: SO42−, NO3−, NH4+) concentrations (average ± SD) in Beijing.
From: Combined short-term and long-term emission controls improve air quality sustainably in China
a pre-Olympic Games (Olympic) (Jun. 1–30, 2008), Olympic (Aug. 8–24, 2008) and post-Olympic (Sep. 24–Oct. 23, 2008); b pre-Asia-Pacific Economic Cooperation Summit (APEC) (Oct. 1–31, 2014), APEC (Nov. 1–12, 2014) and post-APEC (Nov. 13–Dec. 31, 2014); c pre-Military Parades (Parade) (Aug. 3–19, 2015), Parade (Aug. 20–Sep. 3, 2015) and post-Parade (Sep. 3–29, 2015); d pre-Belt and Road Summit (BRS) (Apr. 28–May 7, 2017), BRS (May 8–17, 2017) and post- BRS (May 18–Jun. 17, 2017 May 18–Jun. 17, 2017); dark orange in X axis - PM2.5 concentration, orange - gas precursor concentrations, light orange - ionic concentrations in PM2.5; e the period of August 2005 to August 2020; f the period of January 2005 to January 2020. Source data are provided as a Source Data file.
