The levels of particulate matter 2.5 micrometers and less in diameter exceeded its safe threshold in 49 provinces this morning and local people were advised to stay indoors.
Sharing the information, Attapon Charoenchansa, director-general of the Pollution Control Department, said PM2.5 remained at unsafe levels in many areas from April 9 because air was stagnant and hotspots were widespread in the country as well as in Laos, Myanmar, Vietnam and Cambodia.
He said that PM2.5 should return to its safe levels in greater Bangkok on April 12-18 when there would be winds.
The director-general of the Pollution Control Department said during Songkran holidays PM2.5 levels would be harmful to health in 17 northern provinces on Tuesday (April 12) and the levels could be high on April 17 and 18 if there were many hotspots in the region. (TNA)