Maximise natural ventilation instead of buying air purifier: NEA

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NEA says no need to buy the device amid virus worries, people should open doors and windows instead

Jun 07, 2021 06:00 am

It is not necessary to use air purifiers at home, and people should instead adopt practices such as opening doors or windows as much as possible to maximise natural ventilation to reduce the risk of getting exposed to Covid-19, said the National Environment Agency (NEA).

This advice comes as sales of air purifiers went up in recent weeks following concerns that Covid-19 may spread through airborne transmission in some settings.

While using the appropriate air purifiers can remove virus aerosols in the air, they cannot act as a substitute for good ventilation, NEA told The Straits Times.

They also cannot act as protection for other household members if one already has or is exposed to the virus.

An NEA spokesman said: "Good ventilation can prevent the accumulation of virus aerosols in the air and reduce the risk of exposure to the virus.

"Members of the public do not need to buy or use air purifiers at home, but may improve ventilation via natural means such as opening doors and windows as much as possible."

The WHO is currently in the process of conducting an analysis of excess deaths during the pandemic.

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It is also more likely for transmission within the household to be via contaminated surfaces and droplets, NEA added.

INTERIM MEASURE

But this does not mean that air purifiers have lost their value. They can still be used as an interim measure in enclosed, poorly ventilated spaces with a high risk of disease transmission or at medical procedures.

Some experts said air purifiers may also come in handy in a confined space.

But they emphasised that people cannot rely on air purifiers alone, as other health measures, such as social distancing and wearing masks, are still critical.

Associate Professor Ernest Chua from the National University of Singapore's Department of Mechanical Engineering said: "The use of portable air purifiers with an efficient Hepa (high-efficiency particulate air) filtration system can certainly help to reduce the risk of airborne transmission of Covid-19. However, they are not silver bullets. Instead, they are part of a larger strategic mitigation plan."

He said that having a large amount of outdoor air would dilute any contaminants, including viruses, in a building.

"Ventilation is the preferred option for spaces of different sizes while air purifiers are effective in handling small spaces, particularly when they are unable to get enough outside air for dilution," he added.

Associate Professor David Cheong from NUS' Indoor Air Quality Research Unit at the Department of Building said an air purifier can provide localised cleaning but may not be able to clean the whole room effectively.

If air purifiers are used as a mitigation measure for enclosed spaces, they should be fitted with high-efficiency filters, such as a Hepa filter, NEA said.

Consumers should also look at the device's clean air delivery rate to determine the size and the number of air purifiers needed.

Pre-school teacher Lim Yan Hui, 24, had been thinking of buying an air purifier but has changed her mind, saying: "I now find natural ventilation the most simple, yet effective, way to reduce the exposure of the virus. We intend to use less of the air-conditioner and open the windows of our home."