Haze update: PSI reading rises beyond 150 again this week

The haze in Singapore has climbed into the unhealthy range again, when the three-hour Pollutant Standards Index (PSI) hit 152 at 1pm on Wednesday.

After a brief respite in the morning, when the PSI reading ranged from 77 at 6am to 91 at 10am, it breached 100 at 11am and continued to climb.

According to the National Environment Agency (NEA), PSI readings of 50 and below denote "good" air quality and 51-100 the "moderate" range. Air becomes unhealthy when the index crosses 100.

The Pollutant Standards Index (PSI) soared to its highest in 16 years on Monday when it hit 155. The record was a reading of 226 in 1997.

The NEA has advised that children, the elderly and those with heart or lung diseases, reduce prolonged or heavy outdoor activities. Everyone else should also limit prolonged or heavy outdoor activities.