Prime Minister Prayut Chan-o-cha is urging people in Bangkok to abandon their cars and instead use public transport, saying the haze which has choked the capital is mainly caused by vehicles.

"If they are able to use vehicles less, they should," the prime minister said. "They may also consider boarding electric trains or buses."

Gen Prayut pointed out that fine dust particles are mostly produced by vehicle engines.

Referring to proposals that vehicles more than 10 years old should be banned, the premier said the issue must be thoroughly considered as it concerns different groups of people.

"It does not mean that old vehicles are not qualified. The context of the country needs to be taken into account," Gen Prayut said.

"The [haze] problem comes mostly from vehicles. About 8,000-9,000 vehicles are inspected every day and stickers are placed on those facing a ban," the prime minister said, referring to truck and bus inspections that started recently.

According to him, checkpoints were set up on six key routes leading to Bangkok to screen trucks and buses coming from other provinces.

He admitted that he has to tread carefully before announcing measures that would concern vehicles.

Meanwhile Facebook user and blogger 'Yannapat Boonkate' called for a group 'Bangkok Spray-In using personal spray bottles at noon on Saturday and again at 6pm Sunday.

The social media call to action was accompanied by a photo of a man in a face mask spraying mist from a small bottle.

"Reduce the dust all over Bangkok," said the post.

By early Friday, 14,130 Facebook users had promised to appear. An accompanying map suggests participants should meet at the old parliament buildings near the former Dusit Zoo off Ratchawithi Road.

The premier also called on people to share photos of vehicles emitting black exhaust fumes online so relevant agencies can deal with them.

He stressed that public buses emitting black fumes must be decommissioned. 

Referring to the two-day school closure, starting Thursday, Gen Prayut said the measure is aimed at safeguarding children who still have low immunity from falling ill.

According to the prime minister, a committee chaired by Deputy Prime Minister and Defence Minister Prawit Wongsuwon would discuss three measures which could be rolled out to combat the haze.

"If a fourth measure is needed, this could be on a disaster level," he said.

Meanwhile, Bangkok governor Aswin Kwanmuang deployed teams to try and combat haze in the capital Thursday.

He said 50 drones, supported by an agricultural drone club, would be used to spray water to help minimise haze in the capital, adding that City Hall will be responsible for all of the expenses.