Pollution chokes Thai capital

Authorities in the Thai capital ordered nearly 450 schools to close yesterday as pollution levels reached dangerously unhealthy levels. Bangkok, the world’s most visited city, saw levels of PM 2.5 particles at 78.3 pg/m3. A level above 35 is considered unhealthy, according to independent air quality monitor AirVisual. PM 2.5 particles can include dust, soot and smoke and are so small they can lodge deep in the lungs and enter the bloodstream. The schools will be closed for one day. Last January, the city closed schools for a week because of pollution.