Clearing the air Clearing the air

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Clearing the air Clearing the air

Monday, 18 May 2020 | Saimi Sattar

Clearing the air Clearing the air

The Coronavirus pandemic has called into question many things that we took for granted, including the use of air conditioners. Saimi Sattar speaks to the experts to dispel myths and changing patterns of use

Imagine a contemporary office or a modern home, and what comes to mind, immediately, are steel and chrome facades, the application of AI so that the lights are switched on and dimmed automatically and the ACs are turned up and down according to the number of people, temperature and time of the day. Did you say ACs? That is one appliance that we have begun to take for granted over the years. But then like all aspects of our lives, this too is bound to be affected by the Coronavirus. There have been assertions floating around that it assists the spread fuelled by the fact that in Wuhan, one family visiting a restaurant spread it to two more who happened to be at the place at the same time.

Dr Rajesh Kumar Gupta, Additional director, Pulmonology and Critical Care, Fortis, Noida, says, “If you look back eight to 10 years, we used to get viral infections in winter. But now they can be seen throughout the year. Doctors believe that this spike is due to the recirculated air in public spaces. If there aren’t adequate filters, the possibility of infection goes up. In a smaller space, like a bus or an aircraft, the problem is likely to multiply.”

And it is not just some doctors who are ringing the alarm bells. Himanshu Agarwal, Founder and CEO, Magneto CleanTech, a company, which develops advanced technologies to tackle the problem of poor indoor air quality in developing nations, says, “One of the most common misconceptions is that air conditioners purify the air while cooling it. However, existing ones are not equipped to do so. They only recycle the air in the room by absorbing it and releasing cooler air. Centralised ACs in large indoor spaces are not sufficient to eliminate viruses or other air pollutants. In fact, they only increase the risk of transmission as several people breathe in the same air that is being recirculated in an enclosed space. A majority of these air conditioning units might be old and contain insufficient filtration to eliminate microbes in the air.”

Gurmeet Singh, Chairman and Managing Director, Johnson Controls-Hitachi Air Conditioning India Ltd, debunks the assertion and says, “The studies till date are not suggesting that the virus is airborne. It is propagated through coughing, sneezing and at times, speaking to an infected person, as the droplets travel a distance of two metres and settle on the surface. Hence, room air conditioners do not pose any additional risk of virus spread.”

Mike Chen, General Manager, TCL India, concurs with him. He says contrary to contributing to the spread, ACs can be beneficial at times. “When it comes to maintaining balanced room temperature, relative humidity and ventilation, ACs can further strengthen human resistance to infections.” He, however, does add certain guidelines while using both residential and centralised ACs to be doubly sure. These include setting the temperature between 24°C and 30°C for stand-alone split and window ACs used at home. “It is also crucial to keep the room ventilated, whenever the device is not in use,” says Chen. This is obviously not possible in offices with fixed windows.

However, the problem is not acute when it comes to the ACs using newer technology, which are equipped with hepa filters that trap not only dust but virus as well. The newer ones are designed to prevent the accumulation of dust and impede the growth of microbes such as spores, viruses and fungi — thus keeping the indoor air pure and clean.

The atmosphere in an individual home where there are only a few people and that of an office, hospital, cinema hall or for that matter any public space is far-removed. Dr Ravi Shekhar Jha, HOD & Sr Consultant, Pulmonology, Fortis Escorts Hospital, Faridabad, says, “There are two-three things that we need to keep in mind while dealing with bigger set-ups like hospitals. The drainage of ACs called the Air Handling Unit of an isolation ward should be separate from that of the rest of the hospital. It needs to maintain negative pressure so that the air does not circulate inside.” Even before the outbreak of Coronavirus, most hospitals did have an isolation ward to deal with infectious diseases adhering to this norm. Dr Jha says that the possibility of transmission through the re-circulated air is miniscule as the virus does not survive in the air for too long.

But there is always the possibility of hitherto undetected patients walking into the common area and infecting others as the centralised AC is common. Dr PK Mangla, Senior Consultant Moolchand Medcity, Delhi, talks about a different aspect of the spread when he says, “Whether it is a hospital or a restaurant and there is an asymptomatic patient, you wouldn’t be aware that s/he is a carrier. The risk of anyone catching the virus is always there when you come in close proximity with the person as the virus is very contagious.”

To avoid that, the health measures that we have been hearing since the beginning of the outbreak are emphasised upon. Dr Jha says, “In a hospital, extra precautions are advised. Every patient walking in, irrespective of whether s/he is COVID-19 positive or not, should wear masks, maintain social distancing and wash hands.”

Singh says that central air conditioning systems used in offices and other commercial applications are well-ventilated. “A standard central air conditioning system design includes a mechanical ventilation-cum-filtration system that draws in adequate fresh air. A central air conditioning system also maintains Relative Humidity between 40 to 70 per cent which is ideal for avoiding the propagation of the COVID-19 virus,” he says.

Moreover, there are certain norms for operating centralised ACs in public areas. Dr Gupta says, “There are clear regulations, which say that the air should be changed 12 times every hour. In fact, the more frequent it is the better is the air quality. In a hot country, it is not possible to do without ACs. Our buildings too are constructed in a manner to accommodate central cooling. Good filters and frequent air changes can tide over any doubts that people might have about AC usage.”

Chen too lists out the precautions that can be taken to prevent the spread of not just COVID-19 but other viruses and bacteria in public spaces. “For public spaces with centralised ACs, in order to avoid mixing of contaminated air with fresh air, exhaust ventilation systems in restrooms should be kept operational 24x7 to avoid virus transmission. Besides, cleaning the air filters more frequently is more important than ever to contain the spread of the virus.”

So the jury verdict is that while the ACs are safe — they are so, only with adequate precautions in place.

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