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01:07 - Source: CNN
Bangkok, Thailand CNN  — 

Thailand’s Ministry of Education has ordered all schools in Bangkok and some surrounding provinces to close for the remainder of the week amid concerns over dangerous levels of air pollution.

Bangkok’s air quality has fallen to harmful levels with the quantity of unsafe dust particles – known as PM2.5 – exceeding what is considered safe in 41 areas around the capital, the country’s Department of Pollution Control said in a Facebook post.

PM2.5 are microscopic particles smaller than 2.5 micrometers in diameter that are considered particularly harmful because they are small enough to lodge deep into the lungs and pass into other organs.

The Air Quality Index, AQI, is used by cities to determine levels of air pollution; according to the World Health Organization, AQI levels under 25 are considered to be acceptable for humans to breathe regularly. The AQI levels on Wednesday evening in Bangkok measured 175.

A woman picks up a child from school early due to toxic levels of air pollution in Bangkok on Wednesday.

Boonrak Yodpetch, secretary general to the Office of Basic Education Commission, said the order for closures came from Prime Minister Prayut Chan-o-cha.

“[The Prime Minister] has ordered the Ministry of Education to consider closing the schools in order to mitigate the health effect,” Yodpetch said Wednesday. “[The] first action is to close down all schools in Bangkok and some schools in four to five provinces (near to Bangkok).

The official said the order would continue through Friday and that a direct result would be the reduction of vehicle traffic. All students were allowed to remain at home except for students preparing for upcoming national tests. In those instances, individual schools could decide whether to reopen.

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Yodpetch added that the situation will be reassessed again on Sunday to determine if schools would stay closed next week.

The order only affects city-managed public schools; private international schools operating in the capital are not compelled to close.

But at least three, the Rasami British International School, the Harrow International School Bangkok and Bangkok Patana School, opted to follow suit and have also closed for the next two days.