Sixty-seven out of 77 provinces in Thailand were shrouded with unsafe levels of ultrafine dust pollution on Thursday morning, according to the Geo-Informatics and Space Technology Development Agency (Gistda).
Three provinces recorded red levels (hazardous to health) of particulate matter 2.5 micrometres and less in diameter (PM2.5), Gistda reported at 8am on Thursday.
Nakhon Nayok faced the highest red level of PM2.5 at 114.3 microgrammes per cubic metre of air over the past 24 hours. It was followed by Prachin Buri (81.8µg/m³) and Samut Songkhram (77.7).
The safe threshold is 37.5µg/m³.
Ten provinces had safe air quality. Nine provinces had moderate air quality represented by yellow levels of PM2.5 ranging from 27 to 36.9. In descending order, they were Chiang Mai, Udon Thani, Nong Bua Lam Phu, Mae Hong Son, Ranong, Surat Thani, Phangnga, Nakhon Si Thammarat and Chumphon.
Good air quality was detected only in Krabi (23.8).
Sixty-four other provinces faced orange levels (starting to affect health) of PM2.5 ranging from 38.3 to 73.8. They included Ayutthaya, Bangkok, Chiang Rai, Chon Buri, Kanchanaburi, Nakhon Ratchasima, Prachuap Khiri Khan, Phuket, Samut Prakan and Songkhla.
The Bangkok Metropolitan Administration (BMA) said on Wednsday that it would ask the government to declare Bangkok an air pollution control area as PM2.5 levels are expected to surge again over the next seven days.
Bangkok governor Chadchart Sittipunt said such a declaration would enable City Hall to draw money from the environment fund to finance efforts to combat the haze problem.
Authorities earlier announced a week of free rides on all public buses and electric train lines in the capital in an effort to reduce car use. Train ridership has risen by as much as 60%, according to initial figures. The free rides are scheduled to end on Saturday.
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