China's air quality worsened year on year in the first two months of 2017 mainly due to unfavorable weather conditions and a warming economy, official data showed.
In the first two months, 338 major cities around China enjoyed good air quality on 64.6 percent of days, down 4.8 percentage points from a year earlier, the Ministry of Environmental Protection (MEP) said in a statement.
The average density of fine particulate matter PM2.5 in those cities rose 12.7 percent to 71 micrograms per cubic meter.
In the Beijing-Tianjin-Hebei region, the share of days with good air quality was down by 19 percentage points to 44.7 percent in the same period, and PM2.5 density surged 48 percent from a year ago, MEP said.
The share of good air days for Beijing plunged 22.5 percentage points to 54.2 percent.
The city of Haikou in southern China's Hainan Province had the cleanest air out of the nation's 74 major cities, while Hebei's capital city Shijiazhuang was the worst polluted.
Chai Fahe, expert with the Chinese Research Academy of Environmental Sciences, attributed the deterioration partly to unfavorable meteorological conditions for pollutants to disperse, including lighter wind and higher humidity in some regions.
The warming economy also weighed on air quality, Chai said.
With recovering production and demand since the latter half of last year, both output and pollutant emissions from high-polluting sectors were on the rise, he said.
China is heading in the right direction for tackling air pollution, head of MEP Chen Jining said earlier this month.
In the past three years, days of good air quality increased in the Beijing-Tianjin-Hebei region, the Yangtze River Delta and the Pearl River Delta, Chen said.
However, the campaign against air pollution cannot be completed in a short period of two or three years, but will need a relatively long time, he added.
"We will make our skies blue again," according to this year's government work report.
In 2017, China will cut the emissions of both sulfur dioxide and nitrogen oxide by 3 percent, and reduce PM2.5 density in key areas markedly, the report said.
