How to fight COVID-19 with ventilation and air purifiers

COVID-19 is an airborne disease, and the latest Omron version of SARS-CoV-2 is by far the most transmissible. While vaccination is effective in reducing the risk of hospitalization and death, awareness of risky situations and taking precautions such as wearing a mask and ensuring ventilation or air purification can reduce your risk of catching the virus. in our last article published in Hindu On January 10th, we discussed the best masks and ways to wear masks. Here, we expand on ventilation and air filtration.

Over the past two years, we’ve learned that viruses are more likely to spread in situations where virus-carrying particles exhaled by an infected person can accumulate in the air (such as cigarette smoke) and others breathe in these particles. . Outdoor, windy conditions where you are not close to anyone are generally safe. On the other hand, if you’re in a crowded outdoor space with no wind for a long time, you’ll be at relatively higher risk. An indoor space that is not well ventilated and in which an infected person is present is probably the most dangerous situation for most people. For example, consider isolating a COVID-19 positive patient in a room and not wearing a mask. The first step to reducing your risk of catching COVID-19 is to wear a well-fitted, high-filtration mask. The second step is to reduce the amount of time you spend in such risky situations. The next steps are ventilation and/or air purification.

What is ventilation?

Ventilation is the act of replacing stale room air with fresh outside air. As more people gather or live in an apartment or office, our activities heat the space and our emitted carbon dioxide (CO.) ₂), leading to undesirable effects such as drowsiness and impaired cognitive function. Very little CO in fresh outdoor air. Might be possible ₂ And indoor can be cooler than room air, and so exposure to fresh air can lower indoor CO. decreases ₂ Levels and cools the indoor space.

If someone in an indoor location is contagious, they emit virus-carrying particles when breathing or talking or shouting or singing. In the same place, uninfected people can then breathe in these viral particles and become infected. So, the simplest solution – natural ventilation – is to open a window to the outside (or keep the shop door open), exchanging virus-laden indoor air for fresh outdoor air.

Natural ventilation may not always be sufficient, as it may depend on wind conditions, window position and size, and other factors. Ventilation can be increased by using box or pedestal fans that bring outside air in through one window or door, with indoor air being naturally pushed out through another open window. However, in hot climates, we do not want warm outdoor air to enter cold indoor residences and workplaces. Moreover, with the increasing air pollution in most of the Indian cities, unfiltered ventilation brings in construction dust and traffic pollution, which is also bad for our health. In this case an air purifier can help.

buy air purifier

Air purifiers can remove airborne particles (whether dust or smoke or virus-carrying particles or other bacteria) and thus limit indoor transmission of COVID-19. Other respiratory illnesses such as flu, colds, and diseases such as tuberculosis are also spread by respiratory particles and droplets. In addition, air pollution from outdoor (construction, traffic) and indoor (natural gas cooking, incense/camphor burning) sources can cause respiratory illnesses, including asthma attacks. Thus, air purifiers in indoor spaces can be beneficial to our health at all times.

There are many such air purifiers available in India, whether in store or with reputable online retailers, and they range in price from ₹4,000 to ₹50,000. So, how do we choose? We recommend air purifiers with high-efficiency particulate air (HEPA) filters. Some units come with activated carbon filters that reduce odors (for example, volatile organic compounds or VOCs), which can also be helpful. Although, electronic air purifier It is not recommended to use ionizers and similar non-HEPA technology. These electronic/ionizer units often perform well below the advertised specifications in your apartment. In addition, electronic/ionizer units can generate harmful byproducts including indoor ozone, ultrafine particles and added VOCs. Just stick to the “simple” HEPA filter.

So, now we have the option of HEPA (with or without activated carbon) air purifiers. How do we decide? Look at the Clean Air Delivery Rate (CADR), which is usually M. is reported in ³/h. Higher is usually better, as rated CADR is only achieved at maximum fan speeds which can be noisy; We may want to run the unit quietly (ie at a low fan speed) in some situations while ensuring satisfactory air filtration. To size an air purifier for an indoor space, calculate ‘Air Changes Per Hour’ (ACH) as ‘ACH = CADR / Room Volume’, where room volume is simply length x width x height (all in meters if the CADR is in m) ³/h). If there is a hall and/or balcony that opens into a room with large open air paths (eg, not always open doors or doors), they should also be included in the ‘room volume’. ACH above five is good; the higher, the better.

We should also note that it is not necessary to buy a commercial air purifier. The past two years have seen do-it-yourself solutions such as the Corsi-Rosenthal Box, which has a box fan on one side and an air filter on four sides. Pran, in partnership with Pan-India conglomerate, Active Buildings, makes Corsi-Rosenthal box-based ‘bubble’ air cleaners, which are priced at the lower end of commercial air purifiers.

While no one can guarantee a zero-risk situation, we can significantly reduce the risk of indoor transmission of COVID-19 (and other respiratory diseases) by using ventilation, air purifiers and high-quality masks in addition to vaccination Huh.

Senior Scientist, Qatar Environment and Energy Research Institute, Doha, Dr. R. Subramaniam (@subu_caps) has worked on air quality research for more than 20 years; and Dr. Madhukar Pai (@paimadhu) is a physician and professor of epidemiology and global health at McGill University, Montreal.