Preserving Indoor Air Clear Can Cut back the Probability of Spreading Coronavirus

Keeping Indoor Air Clean Can Reduce the Chance of Spreading Coronavirus

Open windows and doors to encourage airflow and remove particles from the air. Daniela Torres / EyeEm via Getty Images

Shelly Miller, University of Colorado Boulder

The vast majority of SARS-CoV-2 transmission occurs indoors, primarily through inhalation of particles in the air that contain the coronavirus. Despite the obvious risks that come from inside, small household gatherings are driving much of the recent surge in cases, according to the Centers for Disease Control and Prevention.

The best way to prevent the virus from spreading through a household is to keep infected people away. However, this is difficult to do when an estimated 40% of cases are asymptomatic and asymptomatic people can still transmit the coronavirus to others. Next, the safest thing to do is to chat outside. If you can't, there are some steps you can take to reduce the risk of the coronavirus spreading.

Always wear masks first – and most importantly -, make sure everyone is at least three feet away from other people, and don't spend too much time indoors. However, in addition to these precautions, it can also be helpful to make sure that the air inside is as clean as possible. I'm an indoor air quality researcher studying how to reduce the transmission of infectious diseases in the air. Using increased ventilation or operating an air filter or an appropriately sized filter can add an extra layer of protection.

A table with a cooked meal in a room with the doors and windows open.More ventilation is better. Westend61 via Getty Images

Fresh air is safer air

A safer home is one in which a lot of outside air constantly replaces the stale inside air.

Houses are usually ventilated through open windows or doors or through air entering through accidental openings and cracks in the building itself. A typical air change rate for a house is around 0.5 air changes per hour. Because of the intricate way air moves, it takes about two hours to replace two-thirds of the air in an average home and about six hours to replace everything.

This slow air exchange is not a good thing when you want to limit the spread of a virus in the air. The higher the ventilation rate, the better – so how much fresh air is ideal? While the exact exchange rate will depend on the size of a room, a 10 by 10 foot room with three to four people should have at least three air changes per hour. This should be higher in a pandemic, and the World Health Organization recently recommended six air changes per hour.

There is no need to know the exact air exchange rate for your home. just know that more is better. Fortunately, increasing the ventilation of a house or apartment is easy.

A graphic showing a fan blowing air out of an open window.Fans and exhaust vents can further increase ventilation by pushing indoor air out. Makoto Hara / iStock / Getty Images Plus via Getty Images

Open as many windows as you can – the bigger the opening, the better. Open doors to the outside. Keep the exhaust fans running in your bathroom and over the stove – but only do so if the exhausts are going outside and you also have a window or door open. In addition, you can place fans in open windows and blow out the indoor air to increase the airflow even further.

I live in Colorado and the winter cold is here. I still think it's worth opening windows, but I only open them about halfway and turn on the heaters in my house. It wastes energy, but I keep the time to a minimum and once the visitors leave I keep the windows open for at least an hour to fully ventilate the house.

All of these things add up and increase ventilation.

Filtration as a backup

If you are concerned that your home's ventilation is still too low, air filtration can provide another level of security. Similar to how an N95 mask works, through a filter with small openings in your home, air can capture particles in the air that could contain the coronavirus.

There are two ways to filter air in a home: using a built-in system – such as a. B. central heating – or with the help of independent air purifiers.

At my home, we use both air purifiers and our heating system to filter the air. If you have central heating, make sure your stove filter has a minimum efficiency (MERV) of at least 11. This value describes how effectively a filter removes particles and impurities from the circulating air. A MERV 8 filter is standard on most ovens, and many ovens cannot operate with a more efficient filter. So check your filter and ask a technician before replacing it. However, a MERV 8 filter is better than no filtration at all.

You can also use a stand-alone air filter to remove particulates from the air. However, how effective they are depends on the size of the room. The larger the room, the more air needs to be cleaned, and single cleaners are just as powerful. My home is an open floor plan so I can't use my air filter in the main living area, but it can be helpful in bedrooms or other smaller enclosed spaces. If you are looking to buy an air filter, I worked with some colleagues at Harvard to develop a tool that can help you determine how well an air filter performs for different room sizes.

And don't forget to also consider how effective an air filter's filter is. Your best option is a cleaner that uses a high efficiency particulate air filter (HEPA) as it removes more than 99.97% of all particle sizes.

If you decide to share your home with others in the months to come, keep in mind that it is by far the safest to be outside. However, if you need to be indoors, shorten the length of time your guests are staying, wear masks and social distance at all times. In addition to these precautions, maintaining high airflow by opening windows as wide as possible, allowing more air into your home with exhaust fans, and using air filters and filters can help further reduce the chance of the coronavirus spreading.The conversation

Shelly Miller, Professor of Mechanical Engineering, University of Colorado Boulder

This article is republished by The Conversation under a Creative Commons license. Read the original article.


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