BEIJING (XINHUA) - Moderate to heavy smog has begun to settle on parts of northern China due to falling winds and rising humidity.

Affected regions include the provinces of Hebei, Henan, Shandong and Shanxi, according to the National Meteorological Centre.

The smog will lift or dissipate from Thursday (Feb 22) to Saturday under the influences of cold air and rain, but more smog is expected to appear from Sunday to Monday.

Beijing and surrounding areas reported better air quality in the first month of 2018 as major air pollutants plummeted, the Ministry of Environmental Protection has said.

In 13 cities in the Beijing-Tianjin-Hebei region, "good air" days accounted for 64.5 per cent of the average total last month, up by 28.3 percentage points from a year ago, the statement said.

Beijing saw the biggest improvement as the proportion of days with blue skies reached 80.6 per cent.