SARS-CoV-2 can linger in the air for 30 minutes and travel further than commonly recognised ‘safe distance’

The SARS-Cov-2 coronavirus that causes Covid-19 can linger in the air for at least 30 minutes and travel up to 4.5 metres – much further than the officially recommended “safe distance”, according to a study by a team of government epidemiologists in China.

The findings, which was published in peer-review journal Practical Preventive Medicine last Friday (6 Mar), was the result of a study conducted on a cluster case which originated from a long-distance bus in Hunan on January 22.

The group of government researchers from Hunan province found that in a closed environment with air-conditioning, the transmission distance of the deadly virus will exceed the commonly recognised “safe distance” of 1 to 2 metres, as advised by health authorities around the world.

The researchers also found that the virus could remain afloat attached to fine droplet particles for up to 30 minutes even after the infected carrier had left the bus, proving the importance of washing hands and wearing face masks in public places.

Our advice is to wear a face mask all the way [through the bus ride].

Since China requires closed circuit television cameras to be installed on all long-distance buses, it provided valuable footage for the researchers to reconstruct the spread of the virus on the bus, whose windows were all closed due to air-conditioning being switched on.

In the cluster case that was studied, a passenger, known as “A” (red), boarded a fully booked long-distance coach and settled down on the second last row of the bus.

Graphic by SCMP

The passenger already felt sick at that point but it was before China had declared the coronavirus outbreak a national crisis, so “A” did not wear a mask, nor did most of the other passengers on the 48-seat bus.

The security camera footage showed that throughout the 4-hour journey, passenger “A” did not interact with other passengers but by the time the bus stopped at the next city, the virus had already ‘jumped’ to 7 other passengers (orange).

These included not only people sitting relatively close to “A”, but also 4 victims about 6 rows away from him – roughly 4.5 metres away. They all later tested positive, including 1 passenger who was asymptomatic (blue).

After these passengers left, another group got onto the bus about 30 minutes later. One passenger (pink) sitting in the front row on the other side of the aisle also became infected.

According to Hu Shixiong, the lead author of the study who works for the Hunan Provincial Centre for Diseases Control and Prevention, the latter passenger (pink) who was not wearing a mask, was likely to have inhaled aerosols (light-weighted particles that are formed from tiny droplets of bodily fluids), or tiny particles, breathed out by the infected passengers from the previous group.

The possible reason is that in a completely enclosed space, the airflow is mainly driven by the hot air generated by the air conditioning. The rise of the hot air can transport the virus-laden droplets to a greater distance.

After getting off the long-distance coach, the initial carrier “A” got on a minibus and travelled for another hour. The virus ‘jumped’ to 2 other passengers, one of whom was also sitting about 4.5 metres away from him.

During the course of the study, researchers also found that the virus can last for days on surfaces where respiratory droplets land, raising the risk of transmission if an unsuspecting person touches it and then rubs their face and hands.

The length of time it lasts on the surface depends on factors such as temperature and the type of surface, for example at around 37C (98F), it can survive for 2 to 3 days on glass, fabric, metal, plastic or paper. The virus could also survive more than 5 days in human faeces or bodily fluids.

Additionally, the researchers found during the study that none of those passengers in the 2 buses who wore face masks were infected, thus vindicating the Chinese authorities’ decision to “strongly advise” residents to wear a face mask in public places.

When riding on more closed public transportation such as subways, cars, planes, etc, you should wear a mask all the time, and at the same time, minimise the contact between your hands and public areas, and avoid touching your face before cleaning.

By the time the study was concluded in mid February, passenger “A” had infected at least 13 people.

Meanwhile, one of China’s top epidemiologist Zhong Nanshan said he expects the deadly virus epidemic to keep spreading around the world for the next few months, “until at least June”.

 

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25 Responses to “SARS-CoV-2 can linger in the air for 30 minutes and travel further than commonly recognised ‘safe distance’”

  • Minister ABC, you listening?:

    For sure, the ministers only hear what they want to hear.
    No need to wear mask, and go enjoy huge dinner parties by PA, CC, RC, ETC.

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  • Walao eh, very confusing lay, so must wera mask or not?

    Oops! I forgot, Sinkapore got not enough mask even if want to wear. lol

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  • Extreme Evil:

    The virus creator knows best.

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  • Still ambiguous:

    Base on picture, an enclosed aircon environment. A ( red color ) can spread as far as 4.5m to other victims ( orange color ).

    Vice versa, yet there are those very close ( grey color ) just sitting or standing adjacent of A not affected throughout the whole journey ? How does the virus or infect ( or chose ) the targets successfully ???

    A did not wear masks nor did most of the passengers. If kena should all the people in closes proximity to A should be infected. Yet strangely it did not.

    ————————–

    2 other possibilities to also explore.

    1 What if there are already infected people ( but not sick yet ) besides A already on the same bus ?

    2 What about instead only A who’s sick wear mask and board the bus. Will it still infect the others without masks on the bus ?

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  • NotMyProblem:

    This article will be POFMAed by PAP Minister!

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  • NotMyProblem:

    TRE Techie:
    Walao eh, very confusing lay, so must wera mask or not?

    Oops! I forgot, Sinkapore got not enough mask even if want to wear. lol

    We have “sufficiently” limited masks, so wear only when kenna Covid-19.

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  • PAPVID-20:

    Sorry, pap is not interested in such findings.

    Pap only listens to WHO. That’s why sg is being praised yet again by the WHO yesterday. “Kwai, good boy. You did very well.” Oops! Like praising my pet puppy liddat. lol.

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  • Asd:

    Xi Beh Xia Suay how educated people talk and behave like that and any how assume when there is no evidence to say so

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  • Asd:

    Unapologetic Xia Suay lie when there is no evidence that the virus cannot stay in the air

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  • Beerbelly:

    The study is inconclusive!

    The bug could survive on different kinds of surface for extended period, the unfortunate guy seated 4.5 m away could have been infected by touching the contaminated surface.

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  • Put On Mask:

    Additionally, the researchers found during the study that none of those passengers in the 2 buses who wore face masks were infected, thus vindicating the Chinese authorities’ decision to “strongly advise” residents to wear a face mask in public places.

    If this piece of research is correct and truthful, then it’s safer to put on a mask when in crowded places.

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  • Beerbelly:
    The study is inconclusive!

    The bug could survive on different kinds of surface for extended period, the unfortunate guy seated 4.5 m away could have been infected by touching the contaminated surface.

    What you say is a possibility and all 7 of them could have touched the same infected arm rest or rail. The question is:

    Are you willing to bet your life on it?

    @PAPVID-20

    If you have been paying attention to what China has been doing, you will noticed that they don’t really give a shit about what WHO says. If they had listened, then all Chinese residents would be without masks, like Sinkapore and billions of people in China would have been infected.

    IMHO, those in WHO are merely a bunch of experts (in their own right) uttering politically correct BS to whoever that wants to hear them. They are so behind when it comes to this Covid-19 and mostly only TKSS after it HAS HAPPENED.

    Playback what its head have been saying all this while, has any of his BS benefitted or helped any country in any significant way?

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  • Mav:

    please share a link to the official research document
    I read this news everywhere but no one shares a link to the official research
    if you want to be trusted share the actual research link, otherwise we consider this as fake news
    thank you.

    Tech: https://baike.baidu.com/item/%E5%AE%9E%E7%94%A8%E9%A2%84%E9%98%B2%E5%8C%BB%E5%AD%A6/9604038?fr=aladdin

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  • TruBlu:

    So whats the use of social distancing when 4 metres away CV lingers?

    30K from PRC spread all over tiny mainland SIN CITY.
    They shud be stationed at SENTOSA COVE.

    NO FACE MASKS FOR sinkingPOOReans.
    You die your business.

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  • If non aircon environments:

    What about non air con environment with good sunlight ?
    Is it worst or better ?

    Somebody said to do away with air con, at least temporarily. He may be right.

    I recalled theres a clinic K at TTSH. Mainly for examine suspected TB patients or lungs infected patients. The environment is open , good sunlight , fans only ( non aircon ) and good air circulation.

    Since current issue is air borne as well, we may need to have treatment facilities with no air con.

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  • Spike in coffeeshops:

    Coffeeshops business have shot up by 5-15%
    Based on my defintion and observations.

    Likely due to people shunning aircon foodcourts and malls.

    If not for the desert weather of sg, there would have been hundreds of new cases.

    Yours
    Gan Boh Yong.kim

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  • PAPVID-20:

    @TRE Techie

    I know right. China can’t even be bothered to hue WHO. They just let WHO TKSS as they pleased.

    Some more that annoying Director-General every now and then appeared before the media and frowned his stupid looking face as if he’s on the ground fighting a tough battle with the virus. Sibeh buay tahan.

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  • WHO A Threat To World Health:

    PAPVID-20:
    @TRE Techie

    Some more that annoying Director-General every now and then appeared before the media and frowned his stupid looking face as if he’s on the ground fighting a tough battle with the virus. Sibeh buay tahan.

    If you can’t stand him, do yourself a favour . . .

    https://www.change.org/p/united-nations-call-for-the-resignation-of-tedros-adhanom-ghebreyesus-who-director-general?recruiter=1044739406&recruited_by_id=fb8b5390-5661-11ea-8060-29cd18bea7fb&utm_source=share_petition&utm_medium=copylink&utm_campaign=psf_combo_share_initial&utm_term=f7d1e41671104bf4a7a4c06ab354ce73

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  • SG could have more covid:

    My humble view is the biggest cluster cam come from coffeeshops. Luckily the weather is not cool but like desert. Cos nowadays coffeeshops full house due to eaters Shunning aircons

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  • Soccerbetting2:

    Nowadays, every case with fever, cough,…. or with symptoms similar is deemed as corona virus, probably that is how cases are diagnosed? Maybe not all are corona virus, some may be dengue fevers or whatever, being misdiagnosed as corona virus.

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  • Soccerbetting2:

    Reported on TOC Website :Quote – ”

    The Online Citizen

    More Indonesians carrying Covid-19 virus arriving to seek treatments in Singapore hospitals
    …. 2020-03-13….

    It was reported yesterday that two family members with symptoms from the same Indonesian family arrived in Singapore earlier to seek treatments (‘Two Indonesian family members with symptoms come to S’pore and admit themselves at SGH; both tested positive for Covid-19‘, 12 Mar).

    Both Indonesians, a male and female, presented themselves at the Singapore General Hospital (SGH) on arrival. The man arrived in Singapore first on Sat (7 Mar). After he was tested positive for Covid-19 the next day, the woman immediately came to Singapore on Mon (9 Mar). She was also subsequently tested positive for Covid-19. Both are currently warded in SGH.

    The man was reported to have even gone to a hospital in Jakarta to get treatment before coming to Singapore.

    It’s not known how they managed to pass through the health monitoring stations when they arrived in Singapore since both already have onset of symptoms. It’s also not known if they practised any good social responsibility by wearing a mask in Singapore since they are not well.

    Two more cases of Indonesians flying to Singapore for Covid-19 treatments

    In any case, the Ministry of Health reported nine new cases of Covid-19 yesterday evening. More than half were imported cases…… “Unquote.

    Response :All these Indonesians come here must be thinking Singapore can cure corona virus. Obviously Singapore doctors cannot cure them of corona virus. If not, their medical facilities and doctors in Indonesia are a failures in their own Indonesians mentality, so come to Singapore to seek treatment. Else, they must be too super rich Indonesians to be able to afford Singapore health care costs. Or they are too poor and got misled to believe that Singapore will treat them for “free”. If cannot get “free” in Singapore, not to worry for they still have an option to pretend to be “poor” and use their last card to apply for charity raising money. And those con e*** women wing will very fast response to raise charity money to “help” them. And really how did these corona virus Indonesians get through to Singapore SGH from the custom is really a question mark?

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  • Wear Mask lah:

    Better safe than sorry.
    Wear masks lah..will not do any harm.

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  • Soccerbetting2:

    Everybody think corona virus is useless and bad. However corona virus is not as bad as the evil PAP Women Wing in power. At the very least, corona virus help to stop those Hong Kong people from riot. Did you all still hear of Hong Kong people coming out to walk onto the street rioting any more? Seem like Hong Kong riots has soften down already.

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  • John Lim:

    “The findings, which was published in peer-review journal” This statement means nothing!

    Just because it has been published in peer-reviewed-journal DOES NOT MEAN
    IT HAS BEEN PEER REVIEWED.

    Even if it is “peer reviewed”, it still depends on what the peer reviewers say!

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  • Wear masks lah:

    Better to wear a mask if it helps.
    Anyway, what is the harm?
    Better safe than sorry.
    Better to get more masks in before most countries ban the export. Better still we should be producing the masks here by now. Why our local companies still cannot do it here?
    We must have get our priority wrong. Maybe still chasing after overvalued loss-making companies like WeWork, Uber, Grab, Gojek, OYO etc

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