Singapore air quality returns to moderate range after PSI dip

SINGAPORE – Air quality in Singapore’s central region dipped back into the moderate range at 11pm on Oct 3, some 12 hours after it entered the unhealthy range.

The 24-hour Pollutant Standards Index (PSI) reading at 11pm was 100, a dip from 101 an hour before.

It had hit 102 at 11am the same day, the first time the 24-hour PSI reading in any region here reached unhealthy levels since 10pm on Sept 30.

The PSI readings for the other regions remained in the moderate range throughout Oct 3, ranging between 76 and 93 at 11pm.

The PSI reading is a 24-hour rolling average of six key air pollutants and is used in planning for outdoor activities the next day.

Air quality is considered unhealthy when the 24-hour PSI is in the range of 101 to 200, during which the National Environment Agency (NEA) advises the public to at least reduce outdoor activities.

PSI readings of 51 to 100 are considered moderate, while values of zero to 50 are in the “good” range.

PM2.5 readings across Singapore ranged from 34 to 54 at 11pm, all in the normal band.