For the past few months, Bangkok has been experiencing a smog crisis with very unhealthy pollution levels reaching a 'code red' in some days.
Vehicles emissions, industrial fumes along with agricultural open burning in the region mixed with a high-pressure air system facilitated the build-up of fine particles smog.
From January 29th 2019, the Thai authorities have issued an unprecedented order to shut 437 schools in Bangkok due to the dangerous level of fine particles (including PM2.5) in the air.