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Cutting through the haze: When do you need an N95 mask?

Cutting through the haze: When do you need an N95 mask?

A man sells N95 safety face masks to office workers in Singapore's central business district. (Photo: Reuters/Edgar Su)

SINGAPORE: The National Environment Agency (NEA) said on Tuesday (Sep 17) that it pushed out additional stocks of N95 masks to retail stores over the weekend, amid reports that the masks were sold out at some shops. 

Saturday was the first time since August 2016 that the 24-hour PSI reading reached the "unhealthy" level, after the Pollutant Standards Index (PSI) went beyond the 100 mark at 4pm. 

Air quality again entered the "unhealthy" range on Tuesday and Wednesday.

READ: 'Robust action plans' in place to mitigate haze impact, says NEA

READ: MOE will consider closing schools when air quality forecast enters ‘hazardous’ level

While the NEA has said the government has "sufficient" stockpiles of the masks, here's a guide on how and when you should wear one:


According to NEA’s list of frequently asked questions and answers on its website, in general, a healthy person may want to wear a mask if he has to be outdoors for several hours when the air quality forecast is in the hazardous range.

N95 masks are not necessary if you are going to be indoors or out for only a short period of time, such as commuting from home to school or work.

HDB buildings shrouded by haze in Singapore on Sep 13, 2019. (Photo: Reuters/Feline Lim) FILE PHOTO: Public housing apartment blocks are shrouded by haze in Singapore September 13, 2019. REUTERS/Feline Lim/File Photo

According to NEA, PSI readings below 50 denote good air quality. The air quality is moderate if the reading is between 51 and 100, unhealthy for 101 to 200, and very unhealthy for 200 to 300. A PSI reading above 300 mean air quality is considered hazardous.

When air quality reaches the very unhealthy level, children, the elderly, pregnant women, and those with chronic lung or heart disease should avoid or minimise outdoor activity. If they have to be outdoors for several hours, an N95 mask may help them reduce their exposure.

The agency cautioned, however, that the elderly, pregnant women and those with severe lung or heart problems who have difficulty breathing should consult their doctor as to whether they should use the N95 mask. If they do wear a mask, they should stop doing so if they feel uncomfortable.

Employers of workers who are required to work outdoors for prolonged periods are encouraged to maintain a seven-day stock for immediate response.

National Environment Agency's health advisory. (Image: National Environment Agency)


According to NEA's website, N95 masks increase the effort it takes for one to breathe. For some people, the masks could cause discomfort in breathing, tiredness or headache.

"This may be due to the mask causing increased resistance to breathing, and a reduction in the volume of air breathed," it said.

For most people, this is not serious.

However, some elderly people, people with lung or heart conditions, and women in the later stages of pregnancy may already have reduced lung volumes or breathing issues and should take a break from using the masks if they feel uncomfortable.


The mask will only work if it fits the face of the wearer. If the fit is not good, the air the wearer breathes in will go through the gaps between the mask and his face, and not through the filter as intended.

Haze can contain fine particles that are 2.5 microns or smaller (PM2.5), and studies have shown that N95 masks provide good protection against particle pollutants as they are at least 95 per cent efficient against fine particles that are between 0.1 and 0.3 microns.


Masks are available at major pharmacies and supermarkets, such as Unity, Watsons, Guardian, Cold Storage, Giant and NTUC FairPrice.

NEA said on Tuesday that it has been working with the Ministry of Health since April to ensure stocks of N95 masks are made available in retail shops.

"We will continue to closely monitor the availability of masks to the public," said NEA.

"We would like to assure the public that there are sufficient stocks in the warehouses and government stockpiles," it added.

NEA also said on its website that the national stockpile of N95 masks may be released to the major pharmacies and supermarkets if more are needed.


You can reuse your N95 mask, said NEA. However, the mask should be changed when it is soiled or distorted in shape. It should not be shared.


Haze conditions took a turn for the worse on Friday when PSI readings hiked to high-end of "moderate" level. On Saturday, it reached an unhealthy level for the first time in three years as it surpassed the 100 mark, and remained high through Sunday morning.

The situation improved on Monday, with the PSI in the moderate range, before hitting unhealthy levels again on Tuesday afternoon in certain parts of Singapore.

On Tuesday, NEA also said government agencies in Singapore have put in place "robust action plans" to minimise and manage the impact of haze on the public. 

The plans by the Haze Task Force, comprising 28 government agencies and led by NEA, allow "tiered responses depending on the intensity of haze which is based on the 24-hour Pollutants Standard Index (PSI) readings", NEA added.

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Source: CNA/nr/aj(mn)


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