The haze enveloping Singapore reached unhealthy levels on Thursday, with the PSI recording hitting a high of 108.
The National Environment Agency (NEA) says the three-hour Pollutant Standards Index (PSI) reading rose to 108 at 6pm, after crossing over the 100-mark at 5pm.
The highest three-hour PSI recorded for Singapore was 226 on 18 September, 1997.
A PSI reading of 0-50 means the air quality is in the good range; 51-100 moderate range; 101-200 unhealthy range; 201-300 very unhealthy; and above 300 hazardous. More...