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Home ACs don’t pose coronavirus threat, but central air conditioning could raise risks

As summers approach and the coronavirus pandemic worsens, ThePrint looks at whether it’s safe to turn on home air conditioners.

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New Delhi: As Indians get locked inside their homes for the next three weeks with summers driving up temperatures, an unlikely question has come up amid the pandemic — do air conditioners increase the risk of bringing coronavirus inside homes?

According to experts, home AC units do not pose any additional risk of Covid-19 infection, especially at a time when people are isolated inside their homes with no outside contact.

However, coronavirus can spread within spaces that are centrally air conditioned — such as shopping malls and some modern apartments, especially if an infected person is inside such spaces.

“This virus is not airborne in the same way as viruses that cause common cold and flu. It is just that if a person sneezes, a thick spray gets created — that is when a virus is in the air. But it does not float around in the air — it settles on surfaces and can stay there for a very long time,” explained Sambuddha Chaudhuri, an epidemiologist at the Indian Institute of Technology, Bombay.

“Since it does not stay suspended in the air for a very long time, air conditioners should not be a threat especially if it is in your own house where no one is infected,” he told ThePrint.

“Having said that, in places like centrally air-conditioned shopping centres etc, where there are usually a lot of people, the virus can get recycled in the air for a short span of time,” he warned.

In the wake of the pandemic, the Narendra Modi government has ordered people to stay away from crowded spaces as they can come in contact with someone infected.

If people visit a centrally air conditioned mall during a pandemic, the risk of getting exposed to the coronavirus directly from an infected person is far greater than getting it from the recycled AC air, Chaudhuri said.

Also read: How the coronavirus recession is like World War II

What studies say

While there is very little research on the effects of temperature on the virus, a 2011 study published in the journal Advances of Virology that looked at the transmission of SARS-CoV — another coronavirus that had emerged from China in 2003 — may throw some light.

The research showed that the virus was more stable at low temperature and low humidity environments, which could facilitate its transmission in air-conditioned environments.

Whether the same holds true for the SARS-CoV-2 is not yet well understood. Researchers at Purdue University in the US studied the air conditioning systems on the Diamond Princess — a 3,700-passenger cruise that was placed on lockdown off the coast of Yokohama after a passenger disembarked in Hong Kong and tested positive for the novel virus earlier this month.

According to a Centers for Disease Control and Prevention (CDC) report, 46.5 per cent of the passengers on board the Diamond Princess had infections at the time of testing. Traces of the SARS-CoV-2 was identified on a variety of surfaces in cabins of both symptomatic and asymptomatic passengers up to 17 days after cabins were vacated on the Diamond Princess.

According to Qingyan Chen, a researcher at Purdue University, said cruise ship air conditioning systems are not designed to filter out particles as small as the coronavirus, allowing the disease to rapidly circulate to other cabins.

“It’s standard practice for the air conditioning systems of cruise ships to mix outside air with inside air to save energy. The problem is that these systems can’t filter out particles smaller than 5,000 nanometers. If the coronavirus is about the same size as SARS, which is 120 nanometers in diameter, then the air conditioning system would be carrying the virus to every cabin,” Qingyan has said.

The same would hold true for air conditioning systems in flights.

Also read: Economic costs for India may be huge if COVID-19 fallout lasts 6 months: Arvind Panagariya

What to do at home

However, if a home uses split or window type of air conditioner, there would be no effect on coronavirus transmission, Qingyan told ThePrint.

“For a split type system, please open window a bit to have outdoor air entering room. For window air conditioning system, please increase the outdoor airflow rate if there is an option. If not, please open the window a bit to have more outside air,” he said.

“If one uses central air conditioning system, coronavirus could be transmitted to all the spaces it conditions if return air is used. For central air conditioning systems, I would recommend to use 100 per cent outside air,” he said.

The Federation of European Heating, Ventilation and Air Conditioning Associations (REHVA) has published guidelines on how building services in areas with a coronavirus outbreak should operate to minimise the spread of the infection.

The body recommends buildings to switch on ventilation systems round the clock, or at least extend the operation of ventilation systems as much as possible.

Ventilation rates should be switched to low power when people are absent in order to remove virus particles out of the building. Exhaust ventilation systems of toilets should be kept on 24/7, suggests REHVA. In buildings without mechanical ventilation systems, windows should be kept open for at least 15 minutes before somebody enters, especially if it was previously occupied by others.

However, such places should not keep windows in toilets open as it will encourage contaminated airflow from the toilet to other rooms.

Also read: Use hydroxychloroquine with caution: ICMR warns amid confusion over use of drug for Covid-19


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  1. Research should be carried out to include the process of Pasteurization in AC plants used in hospitals with corona patients to eradicate Corona virus in circulation and govt will be willing to fund such research. Medical staff are being infected despite best isolation presently available.

  2. Good analysis and answers my query. Since those living in NCR have starteed combating the hot and humid conditions and the only way is face this is AC.

  3. Fake news everywhere about Ac..
    My 15 days baby girl sleep in Ac room with me with no health problems now she is 2years already perfectly fine.. Ac give u fresh air from outside by filter and all virus can enter inside… Only if a person already infected in dis room then definately cause air spread every.. Chill put ur Ac on and relax

  4. Hello Readers,

    My society has banned people from using personal air conditioning in their homes citing hear say on the news.
    I have tried explaining to them very logically and have cited this article as well but they fail to understand and are threatening to evict me if I turn my AC on.
    What can I possibly do?
    Please help

  5. all people who read my comment, please reply and let me know your thoughts to correct my neighbor.

    my neighbor says latest inverter ac pushes poisonous gases. any poisonous gases as such?!

    does inverter ac push carbon dioxide??!!

    my neighbor says if ac is put, the room opposite to the outside unit fan will get chilled. is it possible?!!!!!

    my neighbor says ac will cause death if the air from outside unit hits 2 meter away open window!!!!!

    my neighbor says ac is poison???!!!!

    my neighbor says ac outside unit will be very loud and cannot sleep in the night. is it that noisy???????????

    replies to this should help my neighbor correct his understanding!!

    • No sir!
      There is no any chances to emits poisonous gasses in inverter a/c,can use domestic ac like split and window types,
      But lik centrelised ac may can lead some problems is just becouse of if any virus affected person belongs to in tat suituation.

    • In normal Ac we could control the speed of fanonly but in inverter type we could control the speed of compressor as per need. So less power consumed. Beside the all rest technology remain same in both. Every Ac/Fridge consist of 5 main parts , Compressor, Condenser, Expansion valve, Capillary, Evaporator & copper tubing. Inside this copper tube the refrigerant circulate in closed loop & create chillness. So there is no change of emit CO2 or any other poisonous gas. In past the refrigeration system used Chloro flouro carbon (CFC) . So if any leakage happened in tubing then this CFC came out. But we use zero CFC refrigerant. But the matter is that in books that old fundamental there. So this misconception arise amoung peaple. Another thing is there the corona is not propagate through air. The best thing is there every Ac having a filter, which fillter most of the micro particle from air. So don’t worry, you may use your Ac freely.
      Please try to convince your society members
      If they not understood then please called Police for help.

  6. Never forget sir, in India maximum number of secondary & tertiary care hospitals have centralized air conditioners.

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