Isn't that as good as saying that the race will proceed? For the 24-hr PSI to exceed 200 at 5pm means practically a continuous period of PSI > 200 which is not the case.
Going by today's trend, 1 hour 2.5 PSI will start climbing from mid morning till early evening before tapering back down. So for AHM, if the first race starts at 5am, it may not be so dire if they assess the conditions on the morning itself. Later categories may be affected but not the 21km. However if they use other indicators like 24 hr PSI,the outcome could be different. Since they haven't said what criteria they are using, we can only guess. But I believe due to the sheer scale of the event with many people affected, the SAF organisers will probably err on the side of caution. They will probably make a decision by Saturday evening. Let's just wait to see the conditions improve and what decisions they make. I'm quite ok either way.
For the rest of today and tomorrow, the prevailing winds are forecast to blow mainly from the west, and the current hazy conditions are expected to persist. There could be a further deterioration in the air quality in the night should the westerly winds blow in denser haze from Sumatra. The 1-hr PM2.5 concentration over the next 24 hours is expected to fluctuate between Band II (Elevated) and Band III (High). Overall, the PSI for the next 24 hours is forecast to be in the Unhealthy range.