COVID-19: Improving indoor ventilation

Proper ventilation is one way to help prevent the spread of COVID-19. Good ventilation exchanges indoor air for outdoor air, helping to reduce potentially infectious particles in the air indoors.

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Follow personal preventive practices

In addition to following personal preventive practices, good indoor ventilation is one part of preventing the spread of COVID-19. With the increased circulation of some variants of concern that can spread more easily, it is even more important to use multiple personal preventive practices (i.e., a layered approach) to protect yourself and others.

If interacting in an indoor setting, wear masks as recommended, avoid closed, crowded spaces and choose larger rooms where you can be the greatest physical distance possible from those outside your household.

The larger the crowd and the smaller the room, the faster the build-up of potentially infectious respiratory particles in the air.

Natural ventilation

When possible and weather permitting, it is better to choose outdoor settings for activities, especially with those outside of your immediate household. It is still important to continue to follow physical distancing and mask recommendations when outdoors.

A space that feels stuffy, crowded or smelly isn’t well ventilated. If you feel a room isn’t well ventilated, the best option is to leave the room. If you can’t leave the room, increase natural ventilation by opening windows or doors.

In cold or wet environments, or where safety or air quality is a concern, open doors or windows:

If windows have openings at both the top and bottom, consider only opening the top window. This will encourage incoming cold air to mix with warm interior air.

If you are concerned about the ventilation in a room, but can’t open windows or doors:

Heating, ventilation, and air conditioning systems

Many buildings use a central heating, ventilation and air conditioning (HVAC) system. If your home/building has vents in the ceiling, walls or the floor, then it probably uses an HVAC system.

If your indoor space uses one of these systems, you should:

If your kitchen or bathroom has exhaust fans that are vented to the outside, you can run them at a low speed. This will move contaminated air without creating unwanted draft. If your interior exhaust fans are not vented to the outside, they may just recirculate inside air without effective filters.

Air purifiers

Air purifiers are also known as portable air filtration devices with high-efficiency particulate air (HEPA) filters. They can reduce the amount of some viruses in the air when used properly. However, we don’t yet know if air purifiers are effective at reducing the transmission of COVID-19.

Using an air purifier in indoor settings could add an additional layer of protection. An air purifier alone will not prevent the spread of COVID-19. You must also consistently follow personal preventive practices.

Fans and single unit air conditioners

Avoid using portable fans, ceiling fans, and single unit air conditioners if possible. They do not improve ventilation and may circulate the virus in a space.

If you must use a fan or window air conditioning unit, aim the air stream away from people to reduce the spread of potentially infectious respiratory particles.

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