Given this is the season for an increase in respiratory illness, a look at ways to mitigate the risk is essential A white paper from the American Industrial Hygiene Association and The International Institute of Building Enclosure Consultant.
In the area of manufacturing, the groups offer advice for improving air quality and flow in indoor space. (The following is an excerpt from the report.)
It’s important to consider the use of in-room air cleaners throughout your building, especially where people spend long periods of time. In-room air cleaners can help dilute the air indoors, making it safer for the people inside. You should consult with your HVAC professional to determine the effectiveness of and ideal locations for in-room air cleaners.
When selecting an in-room air cleaner, you need to look at the independently verified Clean Air Delivery Rate (CADR). This score is determined using the Association of Home Appliance Manufacturers’ test procedures, which means that devices tested using these protocols can be reliably compared.
Be sure to select an in-room air cleaner with a fan system and filters designed to remove small particles such as smoke. You should also be sure to select a device designed to work for the size of your space.
The higher the CADR, the faster it will clean the air. Check the label for:
• CADR scores for smoke, dust, and pollen. When looking for an in-room air cleaner that can capture viral particles, use the room area value on the CADR label for smoke since these particles are similar in size to viral particles. If the CADR score for smoke is not provided, multiply the manufacturer’s general CADR score recommendation by two-thirds to estimate the value for smoke.
• The largest suggested room size for which the unit is appropriate. This size assumes a ceiling height of up to 8 feet. If your building’s ceiling is higher than 8 feet, you will need to consider a unit with a higher capacity or performance.
You should also consider the number of times the air is filtered into the space in an hour. CADR scores are based on approximately five air changes per hour (ACH), a good baseline for non-medical use. To learn more about other recommended CADR scores for higher risk environments, consult ASHRAE Standard 241, Control of Infectious Aerosols, a code-enforceable standard developed by ASHRAE and published in 2023.
If your air cleaner doesn’t have a CADR score, use the following method to determine the air exchange rate needed for your specific room size:
1. Determine the room size where you plan to use the unit by multiplying the room’s length, width, and height.
2. Multiply the room size by 5 (remember, five air changes per hour is a good baseline).
3. Divide the result from step two by 60 minutes. This will be the target air exchange rate you want for your space.
Once you have selected an air cleaner, place your unit most effectively by considering the following:
• Ensure that your in-room air cleaner is positioned to collect as much room air as possible.
• If you know the potential source of infection, place the unit’s intake nearby. If you don’t know the potential source, put the unit in a location where it directs clean air to those indoors.
• Ensure that nothing — including walls or curtains — interferes with the air cleaner’s outlet or intake.
To ensure air cleaners’ effectiveness, be sure to regularly replace or clean filters according to the manufacturer’s instructions.
Be aware that many new indoor air cleaner products come to market every day and are being sold faster than ever since the start of the COVID-19 pandemic. While many new technologies cite laboratory findings, not everything that happens in a lab can be replicated in real life, and not all studies are independently performed.
To ensure that you select the safest and most effective solution for you, your space, and your community, focus on cost-effective, well known, and repeatedly proven air-cleaning technologies.