SINGAPORE: If you've collected your two free N95 masks to protect yourself from the haze, how long can you use them before they need to be replaced?
The answer depends on how often you wear them, how long you spend outdoors and whether the masks remain in good condition, an expert said.
Free N95 masks are being distributed to eligible Singaporeans after a sharp rise in PM2.5 levels on Wednesday (Oct 14), with air quality deteriorating further in parts of Singapore on Friday.
Here's what you need to know about making the most of your masks, including when to wear them and how to store them between uses.
ARE TWO N95 MASKS ENOUGH?
That depends on how frequently and for how long they are worn, as well as how well they are maintained, said Associate Professor Miranda Loh from the NUS Saw Swee Hock School of Public Health.
"For someone who only wears a mask for short commutes and takes care to keep it clean and in good shape, two masks may be sufficient for a week," she said.
“However, someone who spends several hours outdoors each day would likely need to replace their masks more frequently.”
Prolonged use can cause moisture and dirt to build up, while repeated handling can affect a mask's shape and fit.
"Rather than focusing on a fixed number of days, I would encourage people to pay attention to the condition and fit of their masks and replace them when necessary," Assoc Prof Loh said.
HOW LONG CAN AN N95 MASK LAST, AND CAN IT BE REUSED?
N95 masks can be reused, but there is no fixed number of hours or uses for which they remain effective, said Assoc Prof Loh.
Their lifespan depends on how frequently they are worn and whether they remain in good condition.
For someone who wears a mask only during a short commute, reusing it the following day may be reasonable, provided it has been stored properly and remains clean, dry and undamaged.
But masks should be replaced if they become deformed, torn, dirty or damp, or if they no longer fit snugly against the face.
A poor fit can allow polluted air to enter through gaps around the edges, reducing the mask's effectiveness.
"Over time, moisture from our breath can accumulate in the mask, particularly with prolonged use. I would therefore recommend replacing masks regularly, especially if they are worn for extended periods," Assoc Prof Loh said.
She also advised users to check the fit each time they put on a mask, ensuring there are no gaps around the edges.
HOW SHOULD YOU STORE A USED N95 MASK?
Proper storage can help preserve a mask's condition if it is to be reused.
Assoc Prof Loh advised keeping masks clean and dry, in a place where they will not be crushed or bent out of shape.
A clean paper bag or a container that allows the mask to retain its shape can be suitable.
If a mask becomes damp after use, it should be allowed to dry before being stored to reduce the risk of microbial growth.
Users should also avoid unnecessarily touching the inside of the mask, handling it by its straps as much as possible to keep it clean.
WHEN SHOULD YOU WEAR AN N95 MASK?
Not everyone needs to wear an N95 mask whenever haze conditions worsen.
According to the Ministry of Health's (MOH) haze advisory, healthy people generally do not need N95 masks during their commutes or when indoors.
When the 1-hour PM2.5 reading is in the very high band, healthy individuals should minimise all outdoor activity. Those who need to be outdoors may wear a well-fitting N95 mask to reduce their exposure.
Vulnerable groups, including the elderly, pregnant women and those with chronic heart or lung disease, should avoid outdoor activity when the 1-hour PM2.5 reading is in the high band. If they must go outdoors, they may consider wearing an N95 mask.
Assoc Prof Loh said the decision should take into account a person's health, how long they expect to be outdoors, the intensity of their physical activity and prevailing air quality.
Wearing an N95 mask is generally a "reasonable precaution" when the PSI is in the unhealthy range, particularly for those spending extended periods outdoors, she said.
“I would especially encourage people who are more vulnerable to the effects of air pollution, such as those with asthma or other respiratory or cardiovascular conditions, to consider wearing an N95 mask if they can tolerate it,” she added.
However, the masks can be uncomfortable when worn for long periods, and some people may find it difficult to breathe through them.
Assoc Prof Loh said that vulnerable people should prioritise minimising their exposure by staying indoors as much as possible and reducing outdoor physical activity. A well-fitting N95 mask could provide additional protection when going outdoors is unavoidable.
WHAT IF YOU DON'T HAVE AIR-CON OR AN AIR PURIFIER?
For those without access to air-conditioning or air purifiers, there are still practical steps they can take to reduce their exposure to haze.
Professor Rajasekhar Balasubramanian, NUS Keppel Professor in Sustainability Solutions at the College of Design and Engineering, suggested using fans to improve air movement indoors.
In "extreme cases", wearing a face mask at home was "not a bad idea", he said.
"Of course, we cannot sleep with a face mask on, so some form of ventilation would be very helpful," he added.
Separately, the National Environment Agency (NEA) advises households to close doors and windows when outdoor air quality worsens to slow the entry of haze particles, and to reopen them when conditions improve.
It also recommends reducing indoor sources of pollution, such as cigarette smoke and candles, and using wet-cleaning methods such as mopping or wiping to remove settled dust.
Air-conditioned haze shelters have also been set up at community clubs and selected Residents' Committee and Residents' Network centres.