The government is seeking cooperation with neighbouring countries in the Association of Southeast Asian Nations (Asean) to combat the transboundary haze pollution choking the region.
Speaking after Tuesday's cabinet meeting, Prime Minister Prayut Chan-o-cha said the issue must be put on Asean's agenda if a solution is to be found.
Gen Prayut said Foreign Affairs Minister Don Pramudwinai had sent a letter to member countries seeking their support.
"I signed the letter myself. We want to seek their cooperation, particularly in dealing with slash-and-burn agriculture. Meanwhile, Thai farmers must also cooperate [by avoiding such activities]," the premier said, adding that he told relevant agencies to step up their efforts to tackle the polluting haze.
Mr Don, who is also a deputy prime minister, said on Tuesday that the ministry has been in regular contact with Myanmar and Laos in recent years to reduce transboundary haze.
Mr Don said he met with the ambassadors of the two countries yesterday and impressed upon them the urgent need to work together on this. The Thai ambassadors in Laos and Myanmar also met with the authorities of their host countries to discuss the matter.
"From now on, we will follow through on it and enquire about the daily progress from the two neighbouring countries. We are not pressuring them, but we only want to emphasise the urgent need to fight haze pollution that is harmful to the health of people in their own countries as well as in Thailand."
Wijarn Simachaya, president of the Thailand Environment Institute and a former permanent secretary at the Ministry of Natural Resources and Environment, said the failure to curb the border-crossing haze is partly due to a lack of serious legal enforcement among Asean countries.
"All they can do is seek cooperation. While we are trying to ban the burning of plants, there are also some Thai businessmen investing in monoculture in neighbouring countries," Mr Wijarn said.
He said satellite imaging technology could be used to detect the sources of burning, and the government, which has land allocation projects for communities, should ask local residents to cease their slash-and-burn practices -- or they could have their land rights under those projects revoked.
Interior Minister Anupong Paojinda said provincial governors have the authority to impose measures to control the haze under the guidelines mapped out by the Ministry of Natural Resources and Environment.
Gen Anupong said the next move is to ask motorists to avoid entering areas cloaked in thick haze, as exhaust fumes are one of the main sources of PM2.5.
Deputy Prime Minister and Public Health Minister Anutin Charnvirakul said the ministry has medical supplies, including face masks designed to protect against PM2.5, ready for people in areas hit by unsafe levels of PM2.5, particularly in the North.
There, 4,000 patients a week have been seeking treatment for respiratory illnesses as a result of PM2.5, he said.
The Pollution Control Department said Chiang Rai saw the worst level of PM2.5 yesterday at 530 microgrammes per cubic metre in Mae Sai district.