The 2005-2016 Trends of Formaldehyde Columns Over China Observed by Satellites: Increasing Anthropogenic Emissions of Volatile Organic Compounds and Decreasing Agricultural Fire Emissions

We use 2005-2016 observations of formaldehyde (HCHO) columns over China from the OMI, GOME-2, and SCIAMACHY satellite instruments to evaluate long-term trends in emission inventories of volatile organic compounds (V005) that affect air quality. The observations show large increases over 2005-2016 in the North China Plain (+1.1 +/- 0.5% a(-1) relative to 2005) and the Yangtze River Delta region (+1.5 +/- 0.4% a(-1) relative to 2005), consistent with the trend of anthropogenic VOC emissions in the Multi-resolution Emission Inventory for China (MEIC). Unlike other pollutants, VOC emissions have not been decreasing in recent years. An exception is the Huai River Basin in rural eastern China where the satellite data show rapidly decreasing VOC emissions since the early 2010s that appear to reflect bans on agricultural fires. Plain Language Summary Satellite observations of formaldehyde can detect emissions of volatile organic compounds (V005), which are of concern for air quality. Here we use 2005-2016 satellite observations of formaldehyde over China to infer trends in VOC emissions. We find increases of 13% in the North China Plain and 18% in the Yangtze River Delta. Unlike other pollutants, emissions of VOCs in China have not decreased in recent years. An exception is in rural areas where post-2010 restrictions on crop burning to improve air quality have resulted in sharp decreases of VOC emissions.