The haze returned to Singapore over the last week and air quality crossed the unhealthy range on Saturday, leading to several sports events being called off.
But the situation has not cast a dark cloud over Team Singapore athletes' ambitions for the Nov 30-Dec 11 SEA Games in the Philippines.
It is business as usual for athletes whom The Straits Times spoke to, with some preparing to make adjustments to their training regimens to minimise disruption.
High jumper Michelle Sng, who won gold at the 2017 SEA Games in Kuala Lumpur, said she has either trained indoors when her training programme allowed for it, or cancelled the day's session.
She added: "In 2015, when the haze hit us really bad, we wore masks for training.
"I might have to do it again this year if the haze situation worsens."
Cyclist Calvin Sim, who also won gold in Malaysia in the men's omnium but is competing in road racing this year, said he had trained in worse conditions.
He recalled cycling in 2013 when the three-hour Pollutant Standards Index (PSI) level was at 401 (hazardous).
"I was serving national service then and was commuting home from Mandai to Hougang," he said.
"You feel like you're constantly smelling barbecue smoke, your eyes and throat get a bit irritated."
In 2015, when the haze hit us really bad, we wore masks for training. I might have to do it again this year if the haze situation worsens.
MICHELLE SNG, high jumper and SEA Games defending champion, on moving her training indoors when possible when air quality became bad.
It is a less desirable training option because we will not be in a boat and it does not mirror competition conditions.
DIANA NAI, dragon boat paddler, on training in an indoor pool.
Sim, who has been competing in Bandung, Indonesia, since Wednesday, said he has not been affected by the haze so far but added: "Mentally, I can't let it affect me."
If the 24-hour PSI level exceeds the hazardous 300 level, the 29-year-old said he would move his training sessions - three hours a day, six days a week - indoors on stationary bikes.
The haze is also a concern for the national dragon boat team who train at the Kallang Basin and the Marina Channel four to six times a week.
While their programme has not been affected yet, their contingency plan includes holding indoor pool sessions where the athletes practise paddling individually.
But the dragon boaters feel that the pool conditions do not come close to what they will experience at the Malawaan Park in Subic Bay.
It is also not practical to wear masks which will get wet during their outdoor training.
Women's team member Diana Nai said of training indoors: "It is a less desirable training option because we will not be in a boat and it does not mirror competition conditions.
"And we don't have a racing course indoors that is 200m or 500m in length."
For the golfers, training has gone on as usual, although they were advised to use masks and stay hydrated.
Singapore Golf Association president Ross Tan said training would be moved indoors if the PSI exceeded 200 (very unhealthy level), and that the focus would be on high performance and course strategies.
He added: "This is not the first time we are facing a haze situation. In 2015-2016 when the PSI passed the 300 level, there were some days golf courses suspended play.
"As of now, it is not a major concern. Everything is still pretty normal."