PSI improves but central region remains in very unhealthy range; 24-hour forecast in unhealthy to very unhealthy range: NEA

For most of Friday (Oct 16), residents in Singapore endured poor air quality as the 24-hour Pollutant Standards Index (PSI) stayed in the very unhealthy range in three regions and hourly PM2.5 readings remained in the high band across the Republic.

This was due to dense smoke haze from fires in Kalimantan drifting towards Singapore under prevailing south-easterly winds, the National Environment Agency (NEA) said in its daily haze update on Friday night. Smoke haze was also observed over Sumatra.

Looking ahead, NEA said the 24-hour PSI is forecast to be between 150 to 230. This is in the unhealthy to very unhealthy range, even as some showers are expected over Singapore and surrounding region, including parts of Kalimantan.

Data from the ASEAN Specialised Meteorological Centre shows that there were 262 hotspots in Kalimantan on Oct 15, while 285 hotspots were recorded in Sumatra that day.

But there could be cause for limited optimism on Saturday, with winds forecast to shift to blow from the southeast or south-southeast.

"The transport of smoke haze from Kalimantan to Singapore may be reduced. However, some smoke haze from Sumatra may drift towards Singapore," the agency stated.

On Sunday and Monday, showers are forecast over Singapore and parts of Kalimantan, while winds are expected to gradually weaken and blow from the southeast or south.

"This could further decrease the transport of smoke haze from Kalimantan to Singapore, although some smoke haze from Sumatra may drift towards Singapore," NEA said.

Improved haze situation on Friday night

At 9pm, only the central region PSI reading (219) was in the very unhealthy range, while the eastern (195) and western (198) regions have returned to the high-unhealthy range.

Elsewhere, both northern (156) and southern (181) Singapore remained in the unhealthy range.

Hourly PM2.5 also improved, as all five regions returned to the elevated band.

The highest concentration reading of 136 was recorded in central Singapore, and the next highest reading of 125 was in the western region.

Situation could improve by early November: Grace Fu

During a whole-of-government press conference on the haze situation on Friday afternoon, Minister for Sustainability and the Environment Grace Fu urged Singaporeans to be prepared for the haze to "persist for some time".

"The situation is fluid. Depending on the weather, we can expect air quality to fluctuate, including the possibility of reaching hazardous level (PSI >300)," the minister said.

But she also pointed out that the situation could improve by end-October or early-November as winds become lighter and more variable during the inter-monsoon period.

And by around early-December, with the onset of the northeast monsoon, any haze from Sumatra and Kalimantan will blow in the direction away from Singapore, she added.

While members of the public can use the PSI forecast to plan for their next day activities, they should track the latest hourly PM2.5 concentration readings before taking part in outdoor activities.

Although a low 24-hour PSI may generally indicate a good condition, a high one-hour PM2.5 reading could indicate that conditions have recently worsened, even though the longer-term average has not risen yet.

When PM2.5 concentration readings are in the high band, healthy persons should avoid strenuous outdoor activity for the next hour, while vulnerable persons should avoid all outdoor activity for the next hour.

Those who are vulnerable may also wear to a N95 mask to reduce exposure.

According to a Ministry of Health advisory, members of the public generally do not need to wear N95 masks when commuting to work, school or while indoors.

Instead, reducing outdoor activities and physical exertion can help limit an individual's exposure to haze particles.

However, those who need to spend several hours outdoors when PM2.5 levels are high or very high may consider wearing a well-fitted N95 mask or its equivalent , depending on their health condition and air quality at the time.

Healthy individuals may reduce their exposure by wearing a well-fitted N95 mask or its equivalent when heading outdoors for immediate activities when the one-hour PM2.5 reading reaches Band 4 (very high).

Meanwhile, vulnerable persons such as the elderly, pregnant women and individuals with chronic heart or lung disease may do so when the one-hour PM2.5 reading is in Band 3 (high).

Those with severe lung or heart problems, and those who have difficulty breathing at rest or on exertion should consult their doctor before using an N95 mask or its equivalent.

The ministry also advised those with existing chronic heart and lung conditions to ensure that medications are on hand and readily available.

Anyone who feels discomfort when using an N95 mask or its equivalent should take a break from using it.

10 月 16 日星期五的大部分时间里，新加坡居民都饱受空气质量差的困扰，三个地区的 24 小时污染物标准指数 (PSI) 一直处于非常不健康的范围内，而全国各地的 PM2.5 小时读数也一直处于较高水平。

新加坡国家环境局（NEA）在周五晚间发布的每日烟雾预警中指出，这是由于加里曼丹岛火灾产生的浓烟在盛行的东南风作用下向新加坡飘移所致。苏门答腊岛也观测到了烟雾。

展望未来，新加坡国家环境局表示，预计24小时空气污染指数将在150至230之间。这属于不健康到非常不健康的范围，尽管预计新加坡及其周边地区（包括加里曼丹部分地区）会有阵雨。

东盟专业气象中心的数据显示，10 月 15 日加里曼丹有 262 个热点，而苏门答腊当天记录到 285 个热点。

但周六可能会有一些令人乐观的消息，预计风向将转为东南风或东南偏南风。

该机构表示：“从加里曼丹岛向新加坡输送的烟霾可能会减少。但是，来自苏门答腊岛的部分烟霾可能会飘向新加坡。”

预计周日和周一新加坡和加里曼丹部分地区将有阵雨，风力预计逐渐减弱，并由东南风或南风吹来。

“这可能会进一步减少加里曼丹岛向新加坡输送的烟霾，尽管苏门答腊岛的一些烟霾可能会飘向新加坡，”新加坡国家环境局表示。

周五晚间雾霾情况有所改善

晚上 9 点，只有中部地区的 PSI 读数 (219) 处于非常不健康的范围内，而东部 (195) 和西部 (198) 地区已恢复到高度不健康的范围。

其他地方，新加坡北部（156）和南部（181）的健康状况仍然处于不健康范围内。

PM2.5 小时浓度也有所改善，所有五个地区都恢复到了较高水平。

新加坡中部地区记录到的最高浓度读数为 136，其次是西部地区，读数为 125。

傅慧玲：情况可能在11月初有所好转。

周五下午，在政府就雾霾情况举行的新闻发布会上，永续发展及环境部长傅海燕敦促新加坡人做好准备，雾霾可能会“持续一段时间”。

“情况瞬息万变。根据天气情况，空气质量可能会波动，甚至可能达到危险水平（PSI > 300）。”部长说。

但她也指出，到 10 月底或 11 月初，随着季风间歇期风力减弱且变化无常，情况可能会有所改善。

她补充说，到 12 月初左右，随着东北季风的到来，来自苏门答腊和加里曼丹的任何雾霾都会向远离新加坡的方向吹去。

虽然公众可以利用 PSI 预报来计划第二天的活动，但在参加户外活动之前，他们应该关注最新的每小时 PM2.5 浓度读数。

虽然 24 小时 PSI 值较低通常可能表明空气质量良好，但 1 小时 PM2.5 读数较高可能表明空气质量最近有所恶化，即使长期平均值尚未上升。

当 PM2.5 浓度读数处于较高水平时，健康人群应在接下来的一个小时内避免剧烈的户外活动，而易感人群应在接下来的一个小时内避免所有户外活动。

易感人群也可以佩戴N95口罩以减少感染风险。

根据卫生部的建议，公众在上下班、上学或在室内时一般不需要佩戴 N95 口罩。

相反，减少户外活动和体力消耗可以帮助限制个人接触雾霾颗粒。

然而，当 PM2.5 浓度较高或非常高时，需要在户外待上几个小时的人可以考虑佩戴合适的 N95 口罩或同等防护口罩，具体取决于他们的健康状况和当时的空气质量。

健康人群在户外进行紧急活动时，如果一小时 PM2.5 读数达到 4 级（非常高），则可以通过佩戴贴合良好的 N95 口罩或同等口罩来减少接触。

同时，老年人、孕妇和患有慢性心脏病或肺病的弱势群体可以在一小时 PM2.5 读数处于 3 级（高）时这样做。

患有严重肺部或心脏疾病的人，以及在休息或运动时呼吸困难的人，在使用 N95 口罩或同等防护用品之前，应咨询医生。

该部门还建议患有慢性心脏和肺部疾病的人确保手头备有药物，并能随时取用。

任何人在使用N95口罩或同等防护口罩时感到不适，都应该暂停使用。