One of Malaysia's biggest marathons has been cancelled with authorities concerned thick smoke from several Indonesian forest fires may cause health problems for the 30,000 runners taking part.
Organisers of the Standard Chartered Kuala Lumpur Marathon, which was to be run on Sunday (local time), said it would not be held due to worsening air quality in Kuala Lumpur, which was shrouded in an acrid grey haze from the slash-and-burn fires.
Close to half of Malaysia's 52 pollutant monitoring stations around the country, including those in the capital, registered "unhealthy" air quality on Saturday.
"The health and safety of all our runners remains our top priority," organisers of the marathon, with prize money at US$120,000 (NZ$186,000), said in a statement on their website on Saturday.
The haze has afflicted large swathes of Southeast Asia for weeks, sparking health alerts,school shutdowns and affecting flights.
Robert Field, a Columbia University scientist based at NASA's Goddard Institute for Space Studies, has been quoted by the space agency as saying that a possible longer dry season might make the 2015 haze crisis "the most severe on record".
Scientists predict the current crisis could surpass 1997 levels, when out-of-control fires sent pollution soaring to record highs in an environmental disaster that cost an estimated US$9 billion.
The fires on plantations and peatlands that are being illegally cleared by burning are located on Indonesia's huge islands of Sumatra and Borneo.
Runners applauded the cancellation of Kuala Lumpur's 42.2 kilometre marathon, with some taking digs at Indonesia over the mess.
"This cancellation needs an apology from (the) Indonesian government as well," read one comment on Facebook.
The annual Kuala Lumpur race has gained popularity since it started in 2009 with more participants from overseas taking part over the years.