HAIKOU, August 16. /TASS/. From April to June 2021, Hainan's Ecology Department recorded high air quality in the region every day. During this period, the Air Quality Index (AQI) did not exceed 100 and was in line with the standardized ratings of excellent and good, the Haikou Daily reported.
The proportion of time that weather stations reported excellent air quality amounted to 95.9%. For the rest of the time, AQI showed good air quality. The contents of fine particulate matter PM 2.5 (with a diameter of 2.5 microns and less) averaged 11 μg per cubic meter per day. The concentration of other harmful substances corresponded to the first level of the state standard of China, the newspaper writes.
In China, excellent air quality is recorded with AQI from 0 to 50 points, good — from 51 to 100. A value of more than 100 points indicates light air pollution.
When calculating the AQI, the content of PM 2.5, PM 10 particles, sulfur dioxide, carbon monoxide, nitric oxide and ozone in the air is taken into account. Thus, with excellent air quality, the concentration of PM 2.5 does not exceed 35 μg per cubic meter, with good — 75 mcg per cubic meter.
According to official statistics, Hainan is on the list of China's regions with the best ecology. Thus, for about 99.5% of the time in 2020, ecologists recorded excellent and good air quality on the island. The concentration of PM 2.5 particles on the island averaged 13 μg per cubic meter daily.
According to the plans of the provincial authorities, by 2025 the average annual concentration of PM 2.5 particles should be reduced to 11 μg per cubic meter.