NANJING -- East China's economic hub Jiangsu province reported more days with good air quality and record-low average PM2.5 density in 2021, according to the provincial department of ecology and environment.

The average concentration of PM2.5 in Jiangsu was 33 micrograms per cubic meter in 2021, down by 13.2 percent year on year, marking an 8-year straight decline since the data was first collected in 2013. It was also the first time for the province to meet the level-2 national standard for PM2.5 control, which is 35 micrograms per cubic meter.

The percentage of days with good air quality in Jiangsu reached a record high of 82.4 percent during the period.

The PM2.5 reading is a gauge monitoring airborne particles of 2.5 microns or less in diameter, which can penetrate deep into people's lungs.