What to Look for in a Portable Air Cleaner
A portable air cleaner (PAC) can help reduce the number of airborne contagions in your library or classroom, but with so much information to sift through, how do you choose the right one for your space?
Keep reading to learn what to look for in an effective portable air cleaner, according to the Harvard T.H. Chan School of Public Health.
A High-Efficiency Particulate Air (HEPA) Filter
Not all portable air cleaners are made the same. While all of them are designed to reduce pollutants in the air, only those with a HEPA filter have been shown to effectively filter out 99.97% of airborne particles and contagions such as COVID-19, which requires the same rating as smoke or dust filters.
A Variable Fan
PACs that have variable fan speeds can be adjusted for the size of the room and the amount of air exchange needed, and they allow you to lower the noise level when needed.
An Effective Clean Air Delivery Rate
There are a lot of factors that go into figuring out how often fresh air is replaced in your room, including room size, the HVAC system, outside airflow, and any supplementary air cleaners. Five air changes per hour (ACH) are recommended by the Harvard School of Public Health for keeping a room’s air filtered, and this includes the air exchanges from the HVAC system and outdoor airflow.
Air cleaners with a higher clean air delivery rate (CADR) can exchange the air in a standard-size room more often, or serve a larger room. For example, the Phoenix Guardian Air Scrubber has a CADR of 500 cfm and can exchange the air in an 8′H x 30′W x 30′D room (7500 cubic feet) at least four times every hour. Check with the manufacturer of your PAC for specific capabilities.
The Right Size for Your Room
You’ll want to first figure out how many air-cleaning devices you’ll need to cover the square footage of your room. If it’s a large room, you might want to consider using two PACs set at a lower fan rate. This will help combat the fact that the air in most rooms is nonuniform, with some areas being more dense with contagions than others. The effect of air exchange is additive, so if you have two PACs set to exchange the air at a rate of two times per hour, you’ll actually exchange the air four times per hour in your room.
Now that you know what to look for, you can use this calculator created by the Harvard T.S. Chan School of Public Health to figure out how many portable air cleaners you’ll need for your classroom or library. For further reading, check out “What Schools and Libraries Need to Know About Portable Air Cleaners.”