Fine dust reached unhealthy levels in most areas of greater Bangkok over the past 24 hours and is likely to worsen on Friday, with the worst pollution in Bang Phlad and Din Daeng districts of the capital.

The Pollution Control Department reported on Thursday morning that levels of PM2.5 ranged from 42 to 67 microgrammes per cubic metre of air in the past 24 hours. The safe threshold is set at 50mcg.

The best air quality was reported in Khlongchan sub-district of Bang Kapi district and the worst along Din Daeng Road in Din Daeng district and Charan Sanitwong Road in Bang Phlad district of Bangkok.

Of the 43 measurement areas in greater Bangkok, unhealthy levels were reported in 35. For nearby provinces, unhealthy levels were in Phra Pradaeng, Muang and Bang Sao Thong districts of Samut Prakan and Krathum Baen district of Samut Sakhon provinces.

The department attributed the increase in pollution to stagnant air and a high pressure system. It expected fine dust levels to rise in some areas of greater Bangkok on Friday.