Up in the air

Improving indoor air quality (IAQ) helps to reduce the risk of airborne spread of viruses and other contaminants. Covid-19 and other infectious diseases can spread through the inhalation of airborne particles and aerosols.

Better IAQ also reduces the risk of exposure to particles, aerosols, and other contaminants, which is positive for the health of building users. While the best course of action for IAQ will depend on the building’s space and location, there are some fundamental actions to take.

1Start with an IAQ action plan Firstly, your action plan should assess IAQ. Then, it should: ● Set out plans for upgrades and improvements – including HVAC inspections and maintenance; ● Document how HVAC systems work for your building; ● Work with an HVAC expert to assess and inspect systems for ventilation, filtration, and air cleaning; ● Determine how clean outdoor air is brought into and distributed throughout the building; ● Commission, test, and balance building systems so they are functioning as designed; ● Implement carbon dioxide (CO2) monitors; ● Determine how much clean air (outdoor air + filtered HVAC recirculation air) is needed and verify or measure air delivery for each room or space; ● Manage the direction of air flows in higher risk areas of your building such as a school nurse’s office); ● Schedule regular inspections and maintenance, including filter replacements, and HVAC system upgrades or improvements; and ● Provide training and education to the people who operate or help to operate your building and air distribution systems.

2Enhance ventilation Bring clean air from the outdoors into the building and circulate throughout for improved IAQ.

INDOOR AIR QUALITY

The U.S. Environmental Protection Agency’s Clean Air in Buildings checklist suggests good IAQ policy should start with the following three-point strategy

● Be sure that the air from outside is clean or filtered when brought inside; ● Use ‘economisers’ – devices to supplement mechanical cooling with fresh air; ● Run HVAC systems during all occupied hours to ensure clean air enters and is distributed throughout the building; ● Make sure washroom exhaust fans are functioning, with fans running during occupied hours; ● Increase clean, outdoor air at times of higher risk; ● Consider running the HVAC system to refresh air before arrival and/or remove remaining particles at the end of the day (e.g., 1-2 hours before/after the building is occupied); ● Consult an HVAC expert about the maximum outdoor air your system can support; ● Open windows, as weather, outdoor air quality, occupant safety, and HVAC systems permit and enable cross ventilation by opening windows and doors at opposite sides of the room or building. (Note: Opening windows while running HVAC systems may increase energy costs or introduce other air contaminants.)

3Improve air filtration

and cleaning

Make your central HVAC system and in-room air cleaning devices count to clean and filter air. ● Install the highest rated MERV filters the HVAC system can accommodate; ● Close off gaps around air filters to minimise air moving around them instead of through them; ● Use portable air cleaners to increase air cleaning rates in areas where air flow and filtration are insufficient; ● As a temporary measure, do-ityourself air cleaners can also be built from HVAC filters and box fans; ● Increase ventilation and/or filtration in areas with higher emission of airborne particles and aerosols by upping the volume of clean, outdoor air delivery; using portable air cleaners; and setting up extra exhaust ventilation to move air directly to the outside.

The recommendations come from the U.S. Environmental Protection Agency’s Clean Air in Buildings Checklist.