BEIJING — Beijing saw its primary air-pollution index reading fall 32.1 percent year-on-year in the first four months of 2022, official data showed on May 20.

The city's average concentration of PM2.5 was 36 micrograms per cubic meter in the January-April period, said the Beijing Municipal Ecology and Environment Bureau.

PM2.5 readings are a gauge monitoring airborne particles of 2.5 microns or below in diameter.

Beijing authorities have taken considerable measures to tackle air pollution, including promoting new-energy cars and monitoring diesel vehicles.

From January to April, the average concentrations of sulfur dioxide, nitrogen dioxide, and PM10 in Beijing were also down 25 percent, 13.3 percent, and 20.8 percent, respectively, year-on-year, the bureau said.

Beijing made a breakthrough in its air pollution control last year as the city reached the national air quality standard. The city's average concentration of PM2.5 was 33 micrograms per cubic meter in 2021, the lowest level since records began in 2013.