Smog blanketing large swaths of China was thinning out on Thursday, with air pollution in some cities easing, the Ministry of Environmental Protection (MEP) said.

According to monitoring by 10 a.m., smog-hit regions had seen lower readings of PM 2.5, or airborne particles measuring less than 2.5 micrometers in diameter.

However, cities like Jinan and Xi'an were still rated as "gravely polluted".

Other cities including, Beijing, Shijiazhuang, Tianjin, Zhengzhou, Changsha, Chengdu, Shenyang, Changchun and Harbin were rated one level lower, as "seriously polluted".

Major pollutant, PM 2.5, had reduced in Beijing, with the concentration lowering to 213 micrograms per cubic meter at 10 a.m., from 310 micrograms per cubic meter on Wednesday.

The smog has covered 1.15 million square kilometers of China.

The meteorological authorities forecast that the smog will gradually disperse due to rain and snow in central and eastern regions from Thursday through Saturday.