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When discussing methods to minimize the chances of COVID-19 spreading among people within your household, health experts frequently highlight the need to maintain proper ventilation. Yet, the advice often stops there.
Is ventilating your home as straightforward as simply opening a window, or does it involve more? How exactly does ventilation help curb the transmission of viruses? And how does this work during the colder months? Here's what to understand before attending or hosting any holiday gatherings.
In what ways does ventilation reduce the likelihood of COVID-19 spreading?
The belief that fresh air plays a crucial role in preventing the spread of infectious diseases predates the discovery of germ theory. While the science was not fully understood at the time, the basic idea remains unchanged: Replace contaminated air with fresh, clean air from outside (or, later, through an HVAC system).
COVID-19 is transmitted through the air, meaning it spreads when someone breathes in aerosol particles released by an infected individual. The Environmental Protection Agency (EPA) notes that these particles can travel far beyond six feet; they can disperse throughout an entire room or indoor space (although the risk of inhalation decreases with distance). Additionally, the EPA states that these particles can remain suspended in the air even after the infected person has left—sometimes for hours.
While proper indoor ventilation (whether from an open window or an HVAC system) is essential in reducing the transmission of COVID-19, the EPA emphasizes that it cannot completely eliminate the risk. This is why mask mandates remain in place for indoor public spaces.
How to effectively ventilate your home
Opening windows is part of the process, but there are numerous other steps you can take to ensure proper ventilation in your home. Here are some tips from the Centers for Disease Control and Prevention (CDC) and the Environmental Protection Agency (EPA):
Introduce fresh outdoor air into your home
A key note from the EPA: While bringing in outside air, be mindful of your indoor temperature (to avoid making it too cold) and also stay alert to the air pollution levels in your area.
Open windows and screened doors that are safe for everyone in the household (e.g., no risk of falling or triggering asthma symptoms).
Activate any window air conditioner units that have an outdoor air intake or vent, ensuring the vent is open (note that not all window AC units have this feature).
If your HVAC system has an outside air intake, open it (though the EPA notes that this is not a common feature, so refer to your manual before making adjustments).
Push stale indoor air outside
Use fans to help expel indoor air outdoors, whether through a window exhaust fan or a table fan. Ensure the table fan is positioned as close as possible to an open window or door, blowing air outside—and securely placed. The CDC advises not leaving fans unsupervised around young children.
Your stove exhaust fan and bathroom fan can also assist in moving air outside. If you’ve had visitors from outside your household, the CDC recommends running the fans for an hour after they leave.
Promote indoor air circulation
Even if you’re unable to open windows or doors, using fans around your home can still help improve airflow:
Switch on the ceiling fans in your home (after making sure they’re dusted and cleaned).
Ensure any table or box fans are positioned away from people (so contaminated air doesn’t blow directly toward them).
Purify the indoor air
If your home has a central HVAC system (with air ducts throughout the house) that you can access, here’s how to use it to filter your indoor air:
Opt for pleated filters, as they provide superior efficiency compared to standard filters—but make sure a professional installs them for best results.
Ensure the filter you are using is compatible with your unit.
Replace your filter every three months, or as per the manufacturer's guidelines.
If your HVAC fan can be managed by a thermostat, switch the fan setting to 'on' instead of 'auto' when you have guests or want improved airflow in your home. This keeps the fan running continuously, even if your heating or cooling system is off.
If your home lacks a central HVAC system, or you wish to add an extra layer of filtration, consider using a portable high-efficiency particulate air (HEPA) filter. According to the CDC, 'they are the most effective filters available for trapping particles exhaled by people during breathing, speaking, singing, coughing, and sneezing.'
Additional resources and tips for ventilating your home
For more detailed information, or if you want a more scientific approach, the CDC offers a free Interactive Ventilation Tool that asks you to input data about your home and provides insights on its ventilation quality, along with suggestions for improvement. For even more precise guidance, explore the extended version of the model from the National Institute of Standards and Technology.
