Air quality hits unhealthy levels, PSI peaks at 106

SINGAPORE — Air quality reached unhealthy levels yesterday, when the three-hour Pollutant Standards Index (PSI) breached the 100-mark. And the hazy conditions could continue into today, with the 24-hour PSI to be in the moderate range of 51 to 100.

Yesterday, the three-hour PSI crossed into unhealthy territory at 4pm, and peaked at 6pm at 106, before dipping out of the unhealthy range at 8pm. By 9pm, the three-hour PSI reading was 88. The 24-hour PSI readings ranged between 75 to 83.

Responding to media queries, the National Environment Agency (NEA) said: “The haziness is likely due to an accumulation of increased particulate matter in the atmosphere under light wind conditions throughout today. Burning activities in the northern ASEAN region, peninsular Malaysia and Sumatra could have contributed to the increased concentration of particulate matter.” The regional haze map posted on its website showed that clusters of hot spots were detected mainly in Myanmar and some were scattered in Thailand.

Air quality enters the unhealthy level when PSI is between 101 and 200. The three-hour PSI readings began climbing after 7am yesterday, reaching 71 at 11am, 74 at noon and 80 at 1pm. It then hit 86 at 2pm and 94 at 3pm.

The agency added that PM2.5 levels were elevated in most regions of Singapore yesterday. Noting that prevailing winds today are expected to be light and variable in direction, they said hazy conditions can still be expected.

Given the air quality forecast for the next 24 hours, the public can continue with normal activities, the NEA said, but noted that the health impact of haze is dependent on one’s health status, the PSI level and the length and intensity of outdoor activity.