Organizers of the Singapore Grand Prix said Tuesday the haze situation caused by forest fires in Indonesia was volatile but there were no plans so far to cancel the event.
Rain gave the city a welcome respite from the acrid smog but the Pollutant Standards Index (PSI) which measures air quality remained at "unhealthy" levels and grey, fog-like smoke still shrouded the island.
Organizers said there were no plans to amend the program of the nightime street-circuit race and the glitzy public entertainment shows that come with it based on the current air quality levels, but acknowledged the situation was volatile.
"The haze situation is highly changeable not only from day to day, but from hour to hour," Singapore GP said in a statement late Tuesday. "It is currently not possible to reliably predict what the PSI level might be over the race weekend."
Indonesia on Tuesday deployed an extra 1,600 military personnel to fight seasonal forest and farm fires on Sumatra island across the Strait of Malacca from Singapore.
Air pollution indices in Singapore were still in the moderately "unhealthy" range on Tuesday but businesses and schools were operating normally. They reached "very unhealthy" levels after sundown on Monday, limiting visibility in the Marina Bay district where the race will be staged with parties and outdoor concerts on the sidelines.
In Malaysia, the education ministry ordered schools closed in Kuala Lumpur, three adjacent states and the administrative capital of Putrajaya.
Singapore GP said the air quality readings and relevant health advisory would be posted on its website http://www.singaporegp.sg/ and on its official mobile app to help fans "make informed decisions."
They will also be flashed on the giant screen in between races and broadcast on the in-circuit radio system. The health advisory will be posted on all entrances at the circuit.
It said protective respiratory masks "will be available for patrons throughout the ciruit park at cost price," while medical and first-aid posts will be on standby "to handle any possible haze-related conditions."