Organisers of the Singapore Grand Prix say they are monitoring the haze situation ahead of this weekend's event, though have no plans to amend the schedule.
Farmers in nearby Indonesia have been burning forests to create land for agricultural purposes and this has led to a cloud of smog over the region.
On Tuesday, the Pollutant Standards Index [PSI] was registered as 130-161, officially classified as 'unhealthy'.
"Based on the current PSI levels, there are no plans to amend the published racing and entertainment programme," read a statement from race organisers.
"The haze situation is highly changeable not only from day to day, but from hour to hour. Therefore, it is currently not possible to reliably predict what the PSI level might be over the race weekend. We will continue to work closely with all the relevant government authorities to receive the best possible forecasts when they are available."
Event organisers have implemented a number of measures ahead of the weekend's action.
"In order for our patrons to make informed decisions on the haze situation, the PSI reading and relevant health advisory will be displayed on the Singapore GP website, official Singapore GP mobile app, the giant screens between races and broadcast on the in-circuit radio system.
"N95 masks will be available for patrons throughout the Circuit Park at cost price. All of our 24 medical and first aid posts have been placed on standby to handle any possible haze-related conditions."