Employers in the North and other areas should allow their employees to work from home whenever possible because of the high levels of PM2.5, the government said.

Public Health Minister Anutin Charnvirakul on Monday also advised people in regions where fine dust levels are unsafe to wear face masks.

He said that since the beginning of the year about 1.4 million people had been treated for illnesses related to air pollution.

Mr Anutin advised the private sector to arrange for their employees to work from home when possible.

"If private sector workers can work from home, less exhaust fumes would be emitted," he said, before adding the Transport Ministry is rolling out electric buses to help reduce pollution in the capital.

The Pollution Control Department on Monday reported PM2.5 levels of 58-224 microgrammes per cubic metres (μg/m³) in the North.

According to the Meteorological Department, PM2.5 levels will continue to rise until March 20. However, from Thursday, wind will blow the smog away from Bangkok and its vicinity.