Since last December, Bangkok and other parts of the country, especially in the central part and the North, have been under threat caused by this air pollution to the point that it had led to school closures, changes to workers’ work schedules, critical health impacts, and losses to the national economy.

For Bangkok, the prime cause of this pollution is known to be incomplete vehicle engine combustion.

Combined with industrial emissions, and cold weather “inversion” patterns that have trapped the smog close to the ground, the air pollution is aggravated by the heat-trapping effect from Bangkok’s dense, concrete infrastructure that stimulate the formation of an inversion layer that obstructs ventilation.