The Straits Times Run at the Hub and the post-run carnival will go on as planned tomorrow morning if PSI levels are deemed safe enough to hold such activities.
All three categories of the run - 5km, 10km and 18.45km - and the carnival will take place as long as the three-hour PSI level is below the 101-200 range.
If the air quality becomes unhealthy, all running events will be called off. But participants can still look forward to a carnival inside the National Stadium, where they can collect their race entitlements from 8am, listen to live music and win prizes from presenting sponsor Panasonic. Finalists of the grand draw for a Land Rover Discovery Sport will also find out who gets to walk away with a brand-new ride.
Get the latest on the ST Run
Here's how participants can get the latest updates:
Go to The Straits Times' Facebook page
SMS alerts will be sent to the race participants today and early tomorrow morning to advise them of the latest news
How the haze could affect the event
PSI level at 100 or below: Event continues as planned
PSI level at 101-300: Running events cancelled but post-race carnival to go ahead. Participants can collect their race entitlement from 8am. The grand draw for a Land Rover Discovery Sport will also be conducted. Shuttle bus services will still continue for those who have pre-booked.
PSI level at 301 or above: Entire event cancelled
Organisers will decide on a complete cancellation of all events only if the PSI level breaches the 300 mark. Three-hour PSI levels are widely used as a gauge for mass sporting events like runs.
Work to prepare the National Stadium for an estimated crowd of 20,000 tomorrow started yesterday even as three-hour PSI levels hovered in the mid-100s.
Singapore's three-hour PSI levels have fluctuated drastically in the last few days, hitting a high of 341 at 5am yesterday before dropping to a low of 80 at 2pm the same day.
Said ST Run at the Hub organising committee chairman Marc Lim yesterday: "With the haze situation showing considerable improvement from Thursday's hazardous levels, we went ahead with race preparations and are hopeful of good weather on race day.
"But as conditions can change very quickly, we will be waiting until Saturday evening before deciding if we can proceed as planned or will have to call off part of or the entire event for safety reasons.
"But having planned for what we think would be a wonderful morning out, there is no doubt that we remain committed to staging a good event - weather permitting."
SMS alerts will be sent to participants today to inform them if there is a drastic change in air quality that would lead to a cancellation of the event. Should PSI levels hover around the low to mid-100s tonight, a final update will be sent from 2am tomorrow, after taking into account the latest PSI readings ahead of the 18.45km flag-off scheduled at 5am.
Apart from SMSes, runners can also get the latest information on ST's Facebook page or by following @STcom on Twitter.
The ST Run at the Hub 2015 is organised to mark The Straits Times' 170th anniversary and will feature a special 18.45km route - the year the paper was first published.
To celebrate the ST's rich history, readers will be taken on a historical journey of music with live performances by bands and displays of ST's headlines - such as Singapore's separation from Malaysia - over the years during the event.