Data Source and Description
●Mainland China, Hong Kong, Macao and Taiwan's air quality data are obtained from the the ecology and environment departments and environmental monitoring departments at all levels.
●Overseas air quality data come from aqicn, AirNow, OpenAQ, and regional environmental protection bureaus.
●For Air Quality Index (AQI), Chinese standards are used for AQI values for mainland China stations, while local standards or US standards are used for stations in the rest of the regions.●O3-8H is the arithmetic mean of hourly ozone concentration values for the past 8 hours. Since some sites do not have publicly released O3-8H values, the Blue Map presents them according to the statistical method of pollutant concentration data for sites in the Technical Code for Ambient Air Quality Evaluation (for Trial Implementation) (HJ 663-2013). National annual environmental data statistics