BANGKOK — 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.
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.
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.
Could drones help situation?
On Thursday, Thai officials deployed drones to spray water from the sky in a desperate bid to clear the blanket of toxic smog suffocating the city. There had been talk of using a solution of water mixed with molasses to catch the particles in the air on Wednesday but this idea was thrown out.
Asawin Kwanmuang, the governor of Bangkok, told reporters Thursday that more drones would also be used but operators needed more time to clean the machines as they are normally used to spray chemicals on agricultural fields.
But Greenpeace Thailand country director Tara Buakamsri slammed the drone operation as a "stunt" in an interview with CNN.
"Maybe it will bring down, a little bit, the PM2.5 pollution in a specific area but otherwise it is useless," Buakamsri said.
Instead, Buakamsri said the focus should be on the source of PM2.5 particles in the first place such as the increased number of cars on the road and industrial pollution.
"Bangkok is a megacity, one of the biggest megacities in Southeast Asia. There is an ever-increasing number of automobiles on the road causing the emissions of different kinds of air pollution -- particularly diesel cars releasing PM2.5," he explained, before adding, "Another source is coming from factories."
Buakamsri added that the problem with PM2.5 is that it can travel incredibly long distances from its source.
"Bangkok is sometimes affected by transporting the haze pollution from large-scale burning from plantations, from mining from deforestation in Cambodia. So this time is a perfect time for [the] Bangkok area to suffer from the different sources of air pollutants."
City battles choking smog
Thai officials held an emergency meeting Thursday afternoon to work out how to tackle the crisis. The governor invited more than 100 construction operators as well as academics, engineering and pollutions experts and representatives from the Bangkok Aviation Center (BAC) to discuss possible measures.
The BAC offered an outlandish solution, proposing to send all 42 of its small Cessna 172 aircraft to fly across Bangkok with water sprayers installed on each plane.
The plan would see a line of 20 aircraft, spanning approximately 1 kilometer, fly across the city, according to BAC CEO Piya Tregalnon.
Tregalnon told CNN by phone that the idea would only work if the line of aircraft could fly as low as possible -- roughly around the height of Baiyoke Tower II (which stands at 309m).
"We have got to do something about this air pollution. I have got planes and I have talked to engineers it sounds possible. At least we give [it] a try," Tregalnon said.
He said he was waiting for the governor's office to approve plans and issue permits but hoped to start at the weekend.
Earlier this month, officials tried to resolve the poor air quality by spraying water for three days and they're also trying to produce artificial rain, government departments have said. Authorities are also continuing to spray water from fire trucks on the capital's choked streets.
Related: How to manage the polluted air you breathe
The move to close schools has prompted a mixed reaction from residents on social media platforms; some argue it would have been better for students to remain indoors at school, pointing out that the closures have forced parents to take time off work to look after children.
Others praised the decision, saying some schools lack air conditioning, or are semi open-air. Keeping schools open could thus be dangerous for the children.
Poor air pollution could not come at a worse time for the country's tourism sector, with the Chinese Lunar New Year just days away. Thailand is already struggling to win back Chinese vacationers following the deadly boat accident in the waters off the resort island of Phuket last July.
China is the biggest source of foreign visitors to Thailand, where tourism is a major industry. Almost 10 million Chinese nationals visited Thailand last year, according to official statistics.