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Ventilation and Coronavirus (COVID-19)

An important approach to lowering the concentrations of indoor air pollutants or contaminants including any viruses that may be in the air is to increase ventilation – the amount of outdoor air coming indoors. Ensuring proper ventilation with outside air can help reduce the concentration of airborne contaminants, including viruses, indoors. However, by itself, increasing ventilation is not enough to protect people from COVID-19. When used along with other best practices recommended by CDC and others, increasing ventilation can be part of a plan to protect people indoors.

In general, the greater the number of people in an indoor environment, the greater the need for ventilation with outdoor air. In other words, the ventilation rate should be based on the number of people that occupy an indoor space (and a few other factors). In fact, CDC has stated that “Indoor spaces are more risky than outdoor spaces where it might be harder to keep people apart and there’s less ventilation.” Give special consideration to increased ventilation when occupancy is high. Also, make sure high-traffic areas have additional ventilation. In addition to helping reduce risk from airborne transmission of viruses, improving ventilation also benefits indoor air quality by reducing exposure to products used for cleaning and disinfecting potentially contaminated surfaces.

Ventilation in Homes

Opening windows and doors (when the weather permits), operating window or attic fans, or running a window air conditioner with the vent control open increases the outdoor ventilation rate in a home. Do not open windows and doors if doing so poses a safety or health risk to children or other family members (e.g., risk of falling or triggering asthma symptoms). Local bathroom or kitchen fans that exhaust air outdoors and remove contaminants directly from the room where the fan is located also increase the outdoor air ventilation rate. 

Ventilation in Schools, Offices, and Commercial Buildings

Most schools, offices, and commercial buildings have heating, ventilation, and air conditioning (HVAC) systems with filters on them. Typically, these systems are maintained by building or HVAC professionals. Professionals who operate school, office, and commercial buildings should consult guidance by ASHRAE (formerly known as American Society of Heating, Refrigerating and Air-Conditioning Engineers), and other professional and government organizations for information on ventilation and air filtration to help reduce risks from the virus that causes COVID-19. In general, increasing ventilation and filtration is usually appropriate; however, due to the complexity and diversity of building types, sizes, construction styles, HVAC system components, and other building features, a professional should interpret ASHRAE guidelines for their specific building and circumstances.

Increasing ventilation with all or mostly outside air may not always be possible or practical. In such cases, the effective rate of ventilation per person can also be increased by limiting the number of people present in the building in general, or in specific rooms. Administrative practices that encourage remote participation and reduce room occupancy can help reduce risks from SARS CoV-2, the virus that causes COVID-19. See ASHRAE for more information on ventilation rates for different types of buildings and other important engineering controls to manage ventilation, moisture, and temperature in a building.

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Ventilation when cleaning and disinfecting

When cleaning and disinfecting for COVID-19, ventilation is important. Using EPA-registered cleaning and disinfecting products according to their label instructions is the best way to ensure that any indoor air pollution risks are reduced while still maintaining the effectiveness of the disinfecting product. In particular, follow any label precautions that recommend wearing personal protective equipment, like gloves or eye protection, designed to protect the user from the product. As a general precaution, do not mix cleaning or disinfecting products.

In general, increasing ventilation during and after cleaning, for example by opening windows or doors, is helpful in reducing exposure to cleaning and disinfection products and byproducts. Increasing ventilation can also reduce risks from particles resuspended during cleaning, including those potentially carrying SARS-CoV-2 (or other contaminants). Sensitive individuals should avoid cleaning, if possible, and consider leaving the room during cleaning. Sensitive individuals may include pregnant women and people with asthma. Also, sensitive individuals should not be present when disinfectants are being used. Store and use chemicals out of the reach of children and pets. Avoid ventilation with outdoor air when outdoor air pollution is high or when it makes your home too cold, hot, or humid. Check AirNow for information about outdoor air pollution near you.

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