Improving Indoor Air Quality

The most common way COVID-19 is transmitted is through tiny airborne particles of the virus. People who are infected release these particles into the air when they exhale (breathing, speaking, coughing, etc.). The aerosol particles can spread throughout a large room and linger in the air for hours. Because most people spend approximately 90% of their lives indoors, improving the quality of indoor air reduces the spread of respiratory viruses and improves overall health.

Three ways to improve indoor air:

1) Increase air flow (ventilation)

• Open windows and doors to increase outdoor airflow into the building.
• Increase the amount of outdoor air that is pulled in by the Heating, Ventilation, and Cooling (HVAC) system to 100%.

 2) Clean indoor air (filtration)

• Filter viruses and other pollutants out of indoor air.
• If possible, use high-efficiency filters in your HVAC system (MERV 13 or higher). You may need to have your system evaluated by a specialist to determine if your system can handle the high-efficiency filters.
• Use portable HEPA air filters.
• A lower cost option is to make a DIY air filter with a box fan and 4 MERV 13 air filters (Corsi-Rosenthal box).

3) Kill germs in the air using upper room ultraviolet germicidal irradiation

• Ultraviolet Germicidal Irradiation (UVGI) systems can kill germs in the air but do not remove the pollutants. They should be used in addition to improvements in ventilation and filtration.
• UVGI is only intended for specific spaces and not for inside homes. Work with a specialist to see if it will work for your space.

How do you know if your indoor space has adequate ventilation?

One way to test for adequate ventilation is to monitor CO2 levels. We exhale CO2 when we breathe. When people enter a room, the CO2 levels will rise for the first 20 or 30 minutes and then stabilize. If CO2 levels continue to rise after this time, it means that the room is inadequately ventilated, and action to increase airflow should be taken. The CO2 itself is not dangerous (unless it is at extremely high levels); measuring the CO2 levels is a proxy for overall ventilation.

Hays County Local Health Department has CO2 monitors available for local businesses, schools, etc. to check out for 2-3 days at a time. If you are interested in assessing the ventilation in your indoor space, please contact juli.barksdale@co.hays.tx.us for more information.

Improving indoor air quality resources:

Clean Air in Buildings Challenge

Cleanaircrew.org

https://schools.forhealth.org/

https://www.scientificamerican.com/video/how-to-improve-indoor-air-quality/