What Does “proper Ventilation” Mean for Your Home?
When talking about ways to reduce the risk of COVID-19 transmission among people in your own home, public health experts often mention the importance of keeping your home “properly ventilated”. But this is where the instructions end.
Is airing your home as easy as opening a window, or does it require more? How does ventilation help stop the spread of viruses? How does it work in winter? Here’s what to know before any holiday gatherings you decide to attend or host.
How does ventilation reduce the risk of spreading COVID?
The idea that fresh air is the key to preventing the spread of infectious diseases has existed long before the theory of microbes and has gained understanding. The early science was hazy, but the general concept is the same: flush out bad, sick air with fresh, clean air outside (or later, through the HVAC system).
COVID is airborne , which means it can be spread by inhalation of aerosol particles breathed out by an infected person. According to the Environmental Protection Agency (EPA), these particles can travel more than six feet; In fact, they can move throughout a room or interior (although the risk of inhaling particles decreases with distance). What’s more, the EPA states that particles can also remain airborne after an infected person has left a room, sometimes remaining airborne for hours.
While indoor ventilation (through an open window or through a HVAC system) is extremely important to prevent transmission of COVID-19, the EPA emphasizes that it never eliminates the risk entirely. (This is the reason for the ban on the use of closed masks in public places.)
How to properly ventilate the house
Yes, windows do need to be open, but there is much more you can do to properly ventilate your home. Here are some strategies from the Centers for Disease Control and Prevention (CDC) and EPA :
Bring outside air
A general caveat from the EPA: When you bring outside air inside, be sure to keep an eye on the indoor temperature (so it doesn’t get too cold), as well as the air pollution levels in your area. …
- Open all screens and doors that do not pose a health or safety hazard to children or anyone else in the home (such as falling or asthma symptoms).
- Turn on all air conditioner window units that have an air intake or outdoor air vent with the air vent open (not all AC window units have this feature).
- If your HVAC system has an air intake, open it (although the EPA says this is not a normal feature and consult your management before doing anything).
Remove stagnant indoor air outside
- Use fans to move indoor air outdoors using either a window exhaust fan or a table fan. If you are using a desk fan, make sure it is placed as close as possible to an open window or door blowing outward, and that it is placed there safely and securely. The CDC advises not to leave fans unattended with young children.
- An exhaust fan above the stove and a fan in the bathroom can also help push air out of the room to the outside. If you have guests outside of your home, the CDC recommends leaving the fans on for an hour after they have left.
Encourage indoor airflow
Even if you can’t open windows or doors, using fans throughout your home can improve airflow:
- Turn on ceiling fans in your home (if they’ve been washed and scrubbed ).
- Make sure all bench or box fans are directed away from people (so contaminated air does not enter directly on them).
Filter indoor air
If your home has a central heating, ventilation, and air conditioning system (that is, ducts running throughout your home) that you can access, here’s how to use it to filter the air in your room:
- Use pleated filters as they are more effective than conventional filters but must be professionally installed.
- Make sure the filter you are using is correct for the device.
- Change the filter every three months (or as directed by the manufacturer).
- If your HVAC fan can be thermostatically controlled, set the fan to “on” instead of “auto” when you have visitors (or want to increase air flow in your home) to keep the fan running continuously, even if your heating or air conditioning turned off.
If your home does not have a central heating, ventilation, and air conditioning system (or if you want to add another layer of filtration), you might consider purchasing a portable, highly efficient particulate air purifier (HEPA). According to the CDC , “they are the most effective filters on the market for trapping particles that people breathe out when breathing, talking, singing, coughing and sneezing.”
Additional tools and information to ventilate your home
If you want more information or more scientific information about everything, CDC provides a free interactive ventilation tool that prompts you to enter some data about your home, then lets you know how well it is ventilated and how to fix it. For more information, see the expanded version of the model from the National Institute of Standards and Technology .