Levels of PM2.5 soared in most Bangkok districts on Wednesday, prompting the Bangkok Metropolitan Administration (BMA) to call on employers to allow their staff to work from home Thursday and Friday.

AirBKK, the BMA's air quality information centre, reported as of 11am on Wednesday that 20 districts recorded PM2.5 levels of more than 75 microgrammes per cubic metre (µg/m³), which is considered an alarming level in terms of its impact on health. The safe threshold is 37.5 µg/m³.

As the PM2.5 pollution continues to intensify, people living in the city are advised to monitor air pollution levels via AirBKK's Line Alert.

The Pollution Control Department (PCD) on Wednesday forecast that PM2.5 pollution in Bangkok and the surrounding provinces would intensify until Saturday.

Meanwhile, as many as 3,241 fire hot spots were detected between last Saturday and Tuesday in the Central and Northeast regions and 14,939 in neighbouring Cambodia.

An air quality update showed 39 Thai provinces on Wednesday were in PM2.5 pollution red zones, while Bangkok saw 40 districts out of 50 record extremely high PM2.5 levels thus posing a health threat to residents.