Haze watch: Air quality in Singapore deteriorates overnight, unhealthy PSI in 3 regions

Residents in Singapore woke up to unhealthy air quality again with three regions in the unhealthy range on Sunday (Sept 27) morning.

The 24-hour Pollutant Standards Index (PSI) turned unhealthy in central Singapore at 8pm on Saturday, with the western and eastern regions also entering the range at 12am and 1am respectively.

Meanwhile, one-hour PM2.5 reached as high as 131 in central Singapore at 9pm on Saturday before gradually easing back to the lower-end of the elevated band.

At 9am, PSI ranged from 90 to 130 — in the moderate to unhealthy range — with central Singapore recording the highest reading of 130.

One-hour PM2.5 is the normal band for the northern, western and southern regions, while central (68) and eastern (58) Singapore have an elevated concentration reading.

In its daily haze situation update on Saturday evening, the National Environment Agency (NEA) had said the country's 24-hour PSI forecast is expected to be in the moderate to low-unhealthy range.

It pointed out that moderate to dense smoke haze from fires in Kalimantan drifted towards Singapore on Saturday, while smoke plumes were also observed from fires in southern Sumatra.

Along with the prevailing south-easterly or south-westerly winds, there could be a risk of smoke haze affecting Singapore, the agency explained.

It also noted that dry conditions are expected to continue over southern Sumatra and the southern and eastern parts of Kalimantan.

What to do when PM2.5 is elevated

Members of the public should note that the health impact of haze is dependent on one’s health status, the PSI level, and the length and intensity of outdoor activity.

When PM2.5 readings are in the elevated band, members of the public should reduce strenuous outdoor activity for the next hour.

Vulnerable persons such as the elderly, pregnant women, children, and persons with chronic lung or heart disease should avoid strenuous outdoor activity.

However, if readings hit the high-band, all healthy persons should avoid strenuous outdoor activity for the next hour, while vulnerable persons should avoid all outdoor activity.

新加坡居民周日（9月27日）早晨醒来发现空气质量再次不佳，三个地区的空气质量达到不健康水平。

周六晚上 8 点，新加坡中部 24 小时污染物标准指数 (PSI) 达到不健康水平，西部和东部地区也分别在凌晨 12 点和 1 点进入不健康范围。

与此同时，周六晚上 9 点，新加坡中部地区的 PM2.5 一小时浓度一度高达 131，之后逐渐回落至较高水平的下限。

上午 9 点，PSI 指数在 90 到 130 之间——处于中度至不健康范围——其中新加坡中部地区的读数最高，达到 130。

一小时 PM2.5 浓度在新加坡北部、西部和南部地区属于正常范围，而新加坡中部（68）和东部（58）地区的浓度读数偏高。

国家环境局（NEA）在周六晚间发布的每日雾霾情况更新中表示，该国24小时空气污染指数（PSI）预计将处于中度至轻度不健康范围。

报告指出，周六加里曼丹岛火灾产生的中度至重度烟霾飘向新加坡，同时苏门答腊南部火灾也产生了烟柱。

该机构解释说，由于盛行东南风或西南风，新加坡可能会受到烟霾的影响。

报告还指出，苏门答腊南部以及加里曼丹南部和东部地区预计将持续干旱。

PM2.5浓度升高时该怎么办？

公众应注意，雾霾对健康的影响取决于个人的健康状况、PSI 值以及户外活动的持续时间和强度。

当 PM2.5 读数处于较高水平时，公众应在接下来的一个小时内减少剧烈的户外活动。

老年人、孕妇、儿童以及患有慢性肺病或心脏病等弱势群体应避免剧烈的户外活动。

但是，如果读数达到高值，所有健康的人在接下来的一个小时内都应该避免剧烈的户外活动，而易感人群应该避免所有户外活动。