By The Nation
Bang Phlat district reached 53mcg for particulate matter smaller than 2.5 microns (PM2.5), a level considered unhealthy for sensitive groups. Influencing the high level is a high pressure system from the North that is causing an accumulation of low-level dust due to calm winds.
Moreover, the level of PM2.5 in many districts of Bangkok has risen beyond 40mcg per cubic metre. This trend is forecast to continue.
The World Health Organisation places the safety limit at 25mcg.