Heavy rain partly induced by cloudseeding is washing away acrid haze in Sarawak, official data showed today.

Air quality data showed moderate readings in all major towns and more rain is expected in coming weeks, the state Bernama news agency reported.

The Department of Environment's Air Pollutant Index readings showed air quality in Kuching has improved to 72.

The reading in the towns of Sri Aman was 67, Petra Jaya, 66, Sibu, 62 and both the towns of Bintulu and Samarahan posted readings of 58.

A reading between 51-100 shows moderate air quality.

Visibility back to normal levels

Visibility at Kuching at Sunday evening was four kilometres but it improved in most towns in Sarawak to the normal levels of above 10km, the Meteorological Department's website said.

A heavy thunderstorm broke over Sarawak just as a plane was about to take off for a cloud-seeding operation over Kuching, The Star newspaper reported.

Burning in Indonesia and some parts of Malaysia to clear land for crops causes an annual haze that afflicts Malaysia, Singapore and Thailand as well as Indonesia itself.

Peninsular Malaysia has been spared the worst of the haze last week due to the southwest monsoon which was blowing the smoke and dust particles in a different direction.