BANGKOK (REUTERS) - Thailand is preparing face masks for an upcoming regional finance minister and central bank summit after pollution shot air quality to alarming levels, an official said on Tuesday (April 2).

The air quality index (AQI) in Chaing Rai, where Thailand will host the Association of Southeast Asian Nations' (Asean) Finance Ministers and Central Bank Governors' meeting this week, reached levels considered unhealthy at 240 to 250, government data shows.

Masks have been prepared, Nadhavudh Dhamasiri, a senior Finance Ministry official, told Reuters.

Some 300 officials are expected for the meeting, with some already arriving. There are no plans to change the meeting venue or schedules, officials said.

"The dust situation is improving and has not affected the meeting schedules," Nadhavudh added.

The government has already given out nearly 2 million masks to residents in the area, Prime Minister Prayuth Chan-ocha said.

"The smog problem in nine northern provinces is due to agriculture burning in forests, which happens every year," Sate Sampattagul, Head of the Climate Change Data Center at Chiang Mai University, told Reuters.

The smog is worse this year because of a drought and more illegal burning, he added.