Haze update Oct 16: Hourly PM2.5 in high-band across Singapore, very unhealthy PSI in 3 regions10月16日雾霾最新消息：新加坡全境PM2.5小时浓度处于高位，三个区域的空气污染指数（PSI）达到非常不健康水平。
Air quality across Singapore worsened through Friday (Oct 17) morning, with hourly PM2.5 in the high-band across the Republic at 1pm.Southern readings deteriorated the most, surging from 133 to 194µg/m3 at 12pm — the highest concentration reading in the country on Friday, for now. It later dropped to 160µg/m3 at 1pm.Elsewhere, hourly PM2.5 concentration readings are also in the high-band....
Air quality across Singapore worsened through Friday (Oct 17) morning, with hourly PM2.5 in the high-band across the Republic at 1pm.
Southern readings deteriorated the most, surging from 133 to 194µg/m3 at 12pm — the highest concentration reading in the country on Friday, for now. It later dropped to 160µg/m3 at 1pm.
Elsewhere, hourly PM2.5 concentration readings are also in the high-band. The next highest readings were in central (169µg/m3) and eastern (162µg/m3) Singapore.
Meanwhile, the 24-hour Pollutant Standards Index (PSI) remains in the unhealthy to low-very unhealthy range, per forecast by the National Environment Agency on Thursday evening .
The central (226), eastern (205) and western (203) regions remain in the very unhealthy range, while PSI in southern Singapore has reached 185 at 1pm.
As of 10am, outdoor and non-aircon ActiveSG facilities in the eastern, western and central regions are temporarily closed.
The latest list of facilities temporarily closed due to the haze can be found on the ActiveSG Circle website .
Singaporeans who are collecting their N95 masks can use the HazeMaskGoWhere website for more information on the eligibility criteria, collection locations and live updates on mask availability at the vending machines.
When should N95 masks be worn?
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 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).
That said, individuals in this group, including those with severe lung or heart problems, 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, while anyone who feels discomfort when using an N95 mask or its equivalent should take a break from using it.
Can they be reused after short-duration usage?
And for those wondering if N95 masks used for such purposes can be reused after short commutes to transport nodes or eateries, Dr Leong Hoe Nam, infectious disease specialist at Mount Elizabeth Novena Hospital, said that N95 masks can be used for one to two days, provided it remains in good condition.
For hygiene purposes, he recommended storing each used mask inside a sealed Ziploc bag, ideally keeping them dry with a desiccant.
Before reusing the mask, Dr Leong said users should also examine the mask and check for signs of damage, such as frayed edges or holes.
They should then do a "seal check" by gently exhaling to feel for air leaks around the edges, or inhaling to check whether the mask draws inwards towards their face.
If there is a leak, users will feel "a gush at the site of the leak" during exhalation, said Dr Leong.
If it passes the test, he advised users to "keep the mask and keep using" it.
新加坡的空气质量在周五（10 月 17 日）上午持续恶化，下午 1 点，全国 PM2.5 浓度均处于高位。
南部地区的读数恶化最为严重，中午12点从133微克/立方米飙升至194微克/立方米——这是周五全国目前为止的最高浓度读数。随后，下午1点降至160微克/立方米。
其他地区的PM2.5小时浓度读数也处于高位。新加坡中部（169µg/m3）和东部（162µg/m3）的读数也较高。
与此同时，根据国家环境局周四晚间的预测，24 小时污染物标准指数 (PSI) 仍处于不健康至轻微至非常不健康的范围内。
中部（226）、东部（205）和西部（203）地区仍处于非常不健康的范围内，而新加坡南部的 PSI 在下午 1 点已达到 185。
截至上午 10 点，东部、西部和中部地区的室外及无空调 ActiveSG 设施暂时关闭。
因雾霾暂时关闭的最新设施名单可在ActiveSG Circle网站上找到。
新加坡民众领取 N95 口罩时，可访问 HazeMaskGoWhere 网站，了解领取资格标准、领取地点以及自动售货机口罩供应情况的实时更新信息。
N95口罩应该在什么情况下佩戴？
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。
健康人士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），则可以通过佩戴合适的 N95 或同等防护口罩来减少接触。
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。
也就是说，包括患有严重肺部或心脏疾病的人在内的该群体成员，如果在休息或运动时呼吸困难，应在使用 N95 口罩或同等口罩之前咨询医生。
该部门还建议患有慢性心脏和肺部疾病的人确保手边备有药物并随时可用，而任何在使用 N95 口罩或同等口罩时感到不适的人都应该暂停使用。
短时间使用后可以重复使用吗？
对于那些想知道用于此类用途的 N95 口罩在短途通勤到交通枢纽或餐馆后是否可以重复使用的人，伊丽莎白诺维娜医院传染病专家梁浩南医生表示，只要保持良好状态，N95 口罩可以使用一到两天。
出于卫生考虑，他建议将每个用过的口罩存放在密封的 Ziploc 袋中，最好用干燥剂保持干燥。
梁医生表示，在使用口罩之前，使用者还应该检查口罩，查看是否有破损迹象，例如边缘磨损或有孔洞。
然后，他们应该通过轻轻呼气来感受面罩边缘是否有漏气，或者通过吸气来检查面罩是否向内贴合面部，从而进行“密封性检查”。
梁医生说，如果发生泄漏，用户在呼气时会感觉到“泄漏部位有一股液体涌出”。
如果通过测试，他建议用户“保留口罩并继续使用”。