Air quality in central China's Henan Province improved in the first half of this year, thanks to intensified efforts in environmental control in recent years, local authorities said.

The average density of PM2.5, a key indicator of air pollution, in Henan stood at 56 micrograms per cubic meter from January to June, down 20 percent year on year, according to the provincial department of ecology and environment.

The average density of PM10, sulfur dioxide and nitrogen dioxide decreased by 22.5 percent, 16.7 percent and 17.6 percent, respectively, in Henan during the same period.

In recent years, Henan has taken a raft of measures to fight air pollution.

Between 2013 and September 2019, the province scrapped more than 440,000 heavy-polluting and outdated vehicles. It dismantled or upgraded over 2,700 coal-fired boilers, each with a steam generating capacity of no more than 10 tonnes per hour, between 2017 and September 2019.

The air quality improved across China in the January-May period, said a report issued by China's Ministry of Ecology and Environment.

The percentage of days with good air quality was 84.9 percent in 337 cities at and above the prefecture-level from January to May, up 4.6 percentage points year on year. The average concentration of PM2.5 was 39 micrograms per cubic meter during the same period, down 11.4 percent year on year.