BEIJING -- Beijing reported the lowest PM2.5 density among 28 cities within the Beijing-Tianjin-Hebei region and the nearby areas in January.

The average concentration of PM2.5 in Beijing stood at 38 micrograms per cubic meter last month, also ranking the eighth-lowest among 168 major cities nationwide, said the Beijing Municipal Ecology and Environment Bureau on Thursday.

PM2.5, airborne particles smaller than 2.5 micrometers in diameter, pose a significant risk to health.

Beijing reported a 53-percent decrease in PM2.5 density during the 13th Five-Year Plan period (2016-2020) after a spate of measures were taken against air pollution, including the closures of small polluting factories and the increased use of clean energy.

The average concentration of PM2.5 in the metropolis was 38 micrograms per cubic meter in 2020, a year-on-year decline of 9.5 percent and the lowest measurement since the data was first collected in 2013.