PM2.5 dust levels in the atmosphere in 16 northern and north-eastern provinces have exceeded the 50-micron safety standard, but the fine dust in three areas of Chiang Mai and Lampang have reached a health-threatening level in the past 24 hours, according to the Pollution Control Department (PCD).

The PCD’s air quality report at 7am Saturday shows excessive PM2.5 in Chiang Rai, Chiang Mai, Nan, Mae Hong Son, Phayao, Lamphun, Lampang, Phrae, Sukhothai, Tak, Kamphaeng Phet, Mukdahan, Kalasin, Roi-et, Ubon Ratchathani and Si Sa Ket provinces.

The worst areas are in Hot and Chiang Dao districts of Chiang Mai and Mueang district of Lampang, where PM2.5 readings show 185, 136 and 108 microns respectively.

PM2.5 readings in the past 24 hours in the various regions of Thailand are:

• North, 19-185 microns, with most areas exceeding the 50-micron standard level
• North-east, 30-74 microns, with five areas exceeding the standard level
• Central and West, 11-29 microns
• East, 9-31 microns
• South, 10-21 microns
• Bangkok and its suburbs, 8-45 microns