Wuhan has been blanked in grey haze since Friday morning, provincial environment authorities said.

The situation in the capital of Hubei province was the same Monday, and was believed to be triggered by straw burning, according to a statement from the provincial environmental protection department.

The department said wind had carried the smoke from the provinces of Henan and Anhui, to the north.

China is in the middle of its wheat harvesting season. Farmers burn straw after harvesting the wheat from a crop.

The meteorological center of Wuhan said at 9:51 a.m. that the visibility of eastern Hubei will be less than 3,000 meters over the next 12 hours.

Children, the elderly and people with heart or respiratory diseases are advised to stay indoors, according to the statement.

Source:english.sepa.gov