Fine dust was at unsafe levels in most of greater Bangkok on Tuesday morning, the exceptions being Bangkok's Bang Na and Phaya Thai districts and six districts in adjacent provinces.
The Pollution Control Department reported on Tuesday morning that particulate matter 2.5 micrometres and less in diameter (PM2.5) was between 40-81 microgrammes per cubic metre of air over the past 24 hours - and in most of greater Bangkok was at unsafe levels exceeding 50mcg.
The worst level of 81mcg was measured beside Charansanitwong Road in Bang Phlad district of Bangkok.
Safe levels, 42-50mcg, were reported in Bang Na and Phaya Thai districts of Bangkok, Pak Kret district of Nonthaburi, Khlong Luang district of Pathum Thani, Bang Sao Thong and Muang districts of Samut Prakan, Muang district of Samut Sakhon and Muang district of Nakhon Pathom.
The 42mcg level was in Muang district of Nakhon Pathom.
The PM2.5 pollution was not much different from conditions on Monday, the Pollution Control Department said.
It attributed the accumulated air pollution to stagnant air and high air humidity.