生态环境部：今年1-9月全国平均空气质量优良天数比例为87.6%

Core Viewpoint - The air quality and surface water quality in China have shown overall improvement in the first three quarters of this year, with significant reductions in pollutant concentrations and increases in the proportion of days with good air quality [1][5]. Air Quality Summary - The average PM2.5 concentration across 339 cities is 26.0 micrograms per cubic meter, a year-on-year decrease of 5.1% - The average PM10 concentration is 45 micrograms per cubic meter, down 4.3% year-on-year - The proportion of days with good air quality is 87.6%, an increase of 1.8 percentage points year-on-year - The proportion of days with heavy pollution or worse is 1.1%, unchanged from the previous year [5]. Key Regions - In the Beijing-Tianjin-Hebei region, the average PM2.5 concentration is 33.0 micrograms per cubic meter, a decrease of 15.6% year-on-year - The proportion of good air quality days is 73.5%, up 8.5 percentage points year-on-year - The proportion of heavy pollution days is 0.8%, down 1.2 percentage points year-on-year - In the Yangtze River Delta, the average PM2.5 concentration is 29.6 micrograms per cubic meter, a decrease of 6.3% year-on-year - The proportion of good air quality days is 81.6%, up 2.4 percentage points year-on-year - The proportion of heavy pollution days is 0.2%, down 0.4 percentage points year-on-year - In the Fenwei Plain, the average PM2.5 concentration is 30.9 micrograms per cubic meter, a decrease of 16.5% year-on-year - The proportion of good air quality days is 75.3%, up 9.4 percentage points year-on-year - The proportion of heavy pollution days is 2.0%, up 0.9 percentage points year-on-year [5]. Surface Water Quality Summary - Among 3,641 national surface water monitoring sections, the proportion of good water quality (Class I-III) is 89.0%, an increase of 0.5 percentage points year-on-year - The proportion of poor water quality (Class V or worse) is 0.7%, unchanged from the previous year - In major river basins, the proportion of good water quality sections is 90.5%, an increase of 0.5 percentage points year-on-year - The proportion of poor water quality sections is 0.5%, an increase of 0.1 percentage points year-on-year - Among 209 monitored key lakes and reservoirs, the proportion of good water quality lakes is 76.6%, a decrease of 2.0 percentage points year-on-year - The proportion of poor water quality lakes is 3.8%, a decrease of 0.5 percentage points year-on-year [6].