The agency announced on its website on Sunday that images taken by Suomi NPP and other satellites on Saturday showed that there were 601 forest and farm fires in Thailand.
GISTDA said the hotspots included 169
in national forest reserves, 153 in protected forests, 130 in farm areas, 79 in farmland reform areas, 53 in other areas and seven along highways.
It said the highest number of fires, or 110, are in Kanchanaburi.
Meanwhile, 4,056 hotspots were seen on Cambodian soil, 979 in Myanmar, 622 in Laos and 166 in Vietnam.
Thailand and Cambodia have agreed in principle to jointly fight forest fires and reduce transborder PM2.5 ultrafine pollutants in the air.
The GISTDA said as of 8am on Sunday, 30 provinces in Thailand were found to have PM2.5 pollution readings that went beyond safe levels. Air pollution in most of Bangkok was at a moderate level, though readings in Don Mueang, Lak Si, Nong Khaem, Thawee Wattana, Bang Bon, Phra Khanong and Bangkok Yai crossed the safe level.