SINGAPORE (AP) Billowing smoke from Indonesian forest fires has worsened Singapore's air pollution, raising concern among organizers of this weekend's widely anticipated Formula One night race, as well as in schools that reopened Monday after a weeklong term break.
Large parts of neighboring Malaysia were also shrouded in the gray, acrid pall, and an Indonesian province declared an emergency that closed schools and set up health posts to treat those suffering respiratory problems.
The Pollutant Standards Index, Singapore's main measure of air pollution, rose to 222 in the early hours of Monday, the highest level in a year and above the official ''very unhealthy'' bandwidth of 200, according to the National Environment Agency. This is particularly taxing on young children, the elderly and those with heart or lung diseases.
Persistent haze over the weekend caused the cancellation of several outdoor events, while some organizers of a run required participants to walk the route instead.
The organizers of the Singapore Grand Prix were also keeping a close watch on the situation. The F1 race, to be held Friday to Sunday, will feature superstar drivers including Lewis Hamilton and Sebastian Vettel. The annual extravaganza, which has been held in Singapore since 2008, draws hordes of tourists and racing enthusiasts from the region.
''In the event that the haze caused visibility, public health or operational issues, Singapore GP would work closely with the relevant agencies before making any collective decisions regarding the event,'' the Singapore Grand Prix said in a statement.
However, a decision on whether it will be safe to race will be made by FIA Race Director Charlie Whiting after consulting with drivers and teams. The Singapore Grand Prix has always been held at this time of year, and while there has been some haze in past years due to the forest fires, it has never prevented the race from going ahead.
Tickets for the race have mostly been sold in advance, though uncomfortable atmospheric conditions could affect the turnout at the Marina Bay Circuit.
After touching a high of 222, the pollution index mellowed during the day to 118, classified as ''unhealthy.'' In 2013, the same three-hour index hit a historic high of 401, way above the ''hazardous'' mark of 300.
The thick, dirty white haze also blanketed many parts of Malaysia, with 30 out of 52 air pollutant stations recording unhealthy air levels late Monday, including in Kuala Lumpur and the administrative capital, Putrajaya. The haze affects the region every year, and is largely caused by slashing and burning forests to clear the land for agriculture in Indonesia.
The national government in Jakarta has dispatched planes and helicopters for cloud seeding and water dropping, along with more than 1,000 soldiers sent to Sumatra island to help extinguish the fires.
In peat-rich Riau province on Sumatra island, air quality has worsened in past days, threatening people's health and disrupting flights. Gov. Arsyadjuliandi Rachman declared an emergency in the province Monday, setting up health posts and ordering community health centers to stay open. All of about 40 flights to and from Riau's capital Pekanbaru were canceled on Sunday and Monday.
Around 23,000 people with acute respiratory infections caused by the haze have visited the province's hospitals and health centers since August. Data from the National Disaster Mitigation Agency shows almost four times that number of people were affected with respiratory problems in South Sumatra and South Kalimantan provinces.
Rachel Lian, a Kuala Lumpur resident, said she has kept all windows in her house shut and the air conditioning on continuously for the past few days, while also halting all outdoor activities for her 3-year-old daughter.
''I am really fed up with this annual haze, but what can we do?'' said Lian, who is also taking precaution because she is 7 months pregnant.
Environment Minister Wan Junaidi Jaafar recently said he would meet with his Indonesian counterpart on Sept. 18 and may sign a new pact to solve the haze problem.
The Association of Southeast Asian Nations already has a 13-year-old agreement to resolve the trans-boundary pollution issue. Nasrudin Hassan Tantawi, from the opposition Islamic party, said weak leadership in Malaysia should be blamed for failing to implement the 2002 pact and finding a permanent solution.
Indonesia ratified the agreement in January, which puts the onus of solving the issue on it. If not, it can be held liable for the impact of haze on its neighbors.
Despite the worsening haze, public schools in Singapore reopened on Monday as students started a new term. In a Facebook update on Sunday, Singapore's Ministry of Education said the government and school authorities ''will take mitigation measures based on the health advisory and air quality level for the day.''
Should air quality reach ''very unhealthy'' levels, there will be no exercising in schools, be it indoors or outdoors. Staff and students who feel unwell will be put in an air-conditioned room with an air purifier before being taken to see a doctor, the ministry said.
Once the ''hazardous'' threshold is reached, the ministry will consider closing all primary and secondary schools, which typically sees students from ages 7 to 16.
Last week, Singapore authorities registered their concerns with Indonesia on the deteriorating haze situation and offered help, including firefighting teams and an aircraft for cloud-seeding operations. Indonesian authorities declined the offer.
Associated Press writers Eileen Ng in Kuala Lumpur, Malaysia, and Ali Kotarumalos in Jakarta, Indonesia, contributed to this report.