A precautionary note to the readers here. The PSI from our govt cannot be relied on. First off, they combined the readings for PM10 and PM2.5, which is rubbish because they are particles of totally different size and effect. Secondly, they provide PSI on a 3 hourly average which will smooth down numbers unless it persists.
What saddens me is that they insist on using this stupid measurement to the detriment of us citizens. For example, SAF and schools use the PSI reading for their outdoor physical activities, where the PM2.5 could be above 100 but PSI still puts it as below.