However the northern province of Mae Hong Son still had alarmingly high levels of dust particles of less than 10 micrograms (PM10) or about 284 micrograms per cubic metre of air.

"But with three aeroplanes from the Royal Thai Air Force spraying water in the sky and local people spraying water on the land, we expect the situation in Mae Hong Son to improve too, especially now that the weather is good," Deputy Prime Minister Paiboon Wattanasiritham said yesterday.

Paiboon, the social development and human security minister, chairs a group tasked with tackling the smog crisis in the North.

"We will continue to closely monitor the situation," he said.

In Chiang Rai, the local weather bureau chief Sompol Supakarn said visibility was now between 7,000 and 8,000 metres - compared with 800 and 1,000 metres 15 days ago.

In Chiang Mai, the head of royal rainmaking operations Centre 1 said the amount of PM10 dust particles in Chiang Mai's Muang district had came down to just 83 micrograms per cubic metre (mpcm).

"This is not a harmful level," Somchai Ruangsuttinaruphap said.

However, he said the centre planned to continue its operations for another month to encourage more rain so that the North could fully recover from the smog crisis and drought.

Chiang Mai, Chiang Rai and Mae Hong Son were earlier declared disaster zones due to the serious haze problems.

Mae Hong Son Governor Direk Konkleeb yesterday said he had instructed relevant officials not to take leave or travel out of the province on March 19 and March 30.

"Forest fires may start again at anytime. We need a daily meeting," he said.

Montri Bamrungkij, mayor of Tambon Mae Sariang Municipality in Mae Hong Son, said water trucks were spraying water onto roads, markets and public parks in a bid to fight the haze.

Jirapat Chaikittiporn, who heads a local forest-fire control unit, said relevant officials and local people had already prepared fire-buffer zones in 12 "risky villages" in Mae Hong Son's Mae Sariang district.