A worsening acrid haze from land-clearing fires in Indonesia on Thursday shut more schools here, disrupted travel in Malaysia and drifted thousands of kilometres across the Pacific, officials said.
The annual illegal burn-off in Indonesia, which officials have been accused of doing little to stop, sees choking smoke billow across the region, with Malaysia, Singapore and southern Thailand usually worst affected.
But on Thursday, the haze had spread 3,600 kilometres (2,250 miles) to smother islands in the western Pacific, authorities there said.
In the US-administered Northern Mariana Islands, the Emergency Management Office said the Indonesian fires were the source of haze over the islands.
In Guam, near to the Northern Marianas, acting governor Tim Villagomez said the haze was likely to persist for several days. Motorists were warned to take extra care because of the poor visibility.
The fires have been raging on jungle-clad Kalimantan, the Indonesian portion of Borneo island, and Sumatra, closing schools in Indonesia, delaying flights and forcing residents to don face masks as they cope with the bad air.
Satellite images taken over Borneo on Wednesday showed that although the number of hotspots -- large areas with high temperatures indicating fires -- had dropped in West and Central Kalimantan to 395, the number in South Kalimantan had more than quadrupled from a day earlier to 561.
"The governor has ordered all schools, from kindergarten to high school, to close as of today (Thursday) and only reopen Monday," said West Kalimantan local official Emmy Putrimas, from the provincial capital Pontianak.
Putrimas said people were wearing masks that were being distributed on the streets to try to cope with the deterioration in air quality.
Schools in Palangkaraya, the capital of neighbouring Central Kalimantan, were closed for three days on Tuesday and an aide to the head of the local education office said that it was likely this would be extended.
In Pontianak, visibility was less than 300 meters (yards) while in Palangkaraya, it was just 200 meters, meteorological officials there said.
Health officials in both provinces have said that more people have been seeking medical help for respiratory ailments in recent weeks.
Flights in Indonesia's affected region have been delayed until midday each day for the past week.
In neighbouring Malaysia's Sarawak state air quality remained unhealthy in most areas, with Air Pollutant Index readings of between 106 to 188. The index considers haze levels of 100-200 to be unhealthy.
Travel was also affected.
"The helicopter service, a key mode of transport in Sarawak, has been stopped due to poor visibility," an official with the Department of Civil Aviation in Sarawak's capital Kuching told AFP.
Three scheduled flights operated by Malaysia Airlines were also diverted on Wednesday due to poor visibility, he said.
In peninsular Malaysia, locations in five states, including the tourist destination of Malacca, posted unhealthy air quality between 101 and 116, up from two states on Wednesday.
The grey haze also enveloped Singapore on Tuesday.
In 1997-98 the haze cost the Southeast Asian region an estimated 9.0 billion dollars by disrupting air travel and other business activities.
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