Debunking Common Misconceptions About HEPA Air Purifiers
Breathing clean air inside your home can greatly improve your health, and a HEPA air purifier can help you achieve that goal. However, there is a great deal of inaccurate information out there that can mislead you.
Smarter HEPA is familiar with many of the common misconceptions about HEPA air purifiers, and we aim to debunk those myths with scientific facts. Learn more about why this misinformation exists and familiarize yourself with the truth behind it.
Misconception #1: HEPA Filters Can’t Capture Virus Particles
It is a common misconception that because HEPA filters are rated based on 0.3 microns, that it is the smallest particle size they can capture. However, HEPA filters operate at a microscopic level that relies not only on screening, but also on impaction and diffusion as a result of Brownian motion. Nanoparticles bounce around in random directions and do not have enough momentum to escape, and they get caught in the HEPA fibers.
A study completed by NASA shows that nearly 100 percent of particles do get captured by the HEPA filter. The following graph from the NASA study indicates that the 0.3-micron size is the hardest to capture. Efficiency is actually much higher for the 0.07-micron size of virus particles, as well as larger dust, pollen, and mold particles.
Misconception #2: You Should Only Run the Purifier When Needed
Because air purifiers run on electricity, homeowners looking to save on energy may turn off “unnecessary” electronic devices. Alternatively, you might think you only need to run your purifier when your allergies are acting up or when excess pollution from outside creeps indoors.
Reconsider switching off your purifier, though. Smart Air tested an air purifier in a sealed room in Beijing to see how long it took to remove micron particulates present. After 20 minutes, the particulate levels dropped by 80 percent.
However, that same series of tests also found that once the purifier was turned off, particulate levels crept back up to 100 percent of their previous levels within 80 minutes. Turning your air purifier off will lead to your air becoming polluted again, so we recommend that you leave your purifier on while you’re at home—including while you’re asleep.
Misconception #3: Air Purifiers Dry Out the Air
Home HEPA purifiers go a long way in removing allergens and irritants from the air, but some folks worry that a purifier will also remove humidity. Dry air can be irritating to some airways, so it’s reasonable to worry about lowered humidity levels. The good news is that home HEPA air purifiers do not dry out the air in your home.
Air quality experts at Smart Air tested the Blast Mini purifier in a sealed room to see what effect it had on humidity. Testers burned several cigarettes in the sealed room and turned on the Blast Mini for 25 minutes, using a particle counter to measure pollution and humidity. After 20 minutes, they found that particulate levels had dropped to zero, but humidity levels did not budge.
What About Activated Carbon Filters?
The test described above was performed with the Blast Mini with only a HEPA filter. Humidity tests get a little more complex with the addition of an activated carbon filter because carbon uses adsorption to remove gas pollutants from the air. Adding a carbon filter to your purifier can reduce levels of volatile organic compounds (VOCs).
But does the carbon filter also adsorb water vapor and reduce humidity levels? Smart Air tested their Blast purifier, with both a HEPA filter and an activated carbon filter, to measure its effect on humidity. After running the Blast for 15 minutes, they found that particulate levels reached zero, and humidity dropped by 2 percent.
Adding a carbon filter to your air purifier may have a very minor effect on humidity levels indoors. There could also be variations within the test data, as activated carbon is hydrophobic.
Misconception #4: HEPA Filter Fibers Harm Your Health
HEPA filters are made of a series of interlocking fibers designed to capture tiny particulates in the air. But some people read the word “fibers” and worry about what happens when they shed. Can HEPA filter fibers enter your lungs and harm your health?
Most HEPA filters are made using either fiberglass or a mixture of polypropylene (PP) and polyester (PET)—at Smarter HEPA, all of our HEPA filters are made with polypropylene and polyester. A 1991 study published in Semantic Scholar described scientists’ tests of commercially available HEPA filters, both fiberglass and polypropylene/polyester. They blew clean air at both filters for several hours and measured how many fibers broke off. After six hours, the PP/PET filter shed 300 fiber particles per cubic meter of air, while the fiberglass filter shed 700 particles per cubic meter of air.
That sounds like a lot of fibers but compare those numbers to the average amount of PM2.5, or particles 2.5 microns or less in diameter, that you breathe in every day. The World Health Organization (WHO) recommends an annual limit of 10 micrograms of PM2.5 pollution per cubic meter of air. That’s over 25,000 pollutant particles in the same size range as HEPA filter fibers.
The bottom line is that any fibers that break off from your filter are insignificant to your health when compared to the PM2.5 pollutants the filter removes from the air. Additionally, the American College of Chest Physicians analyzed over 30 studies regarding the health effects of fiberglass dust. While they found that fiberglass particles could potentially irritate the lungs, they are highly unlikely to cause irreversible respiratory damage. In fact, the analysis placed fiberglass filter particles in the same category as dust. And as previously mentioned, the Smart Air HEPA filters sold by Smarter HEPA only use the safer PP/PET material.
Misconception #5: Air Purifiers Should Stay in the Center of a Room
Have you wondered where to put your air purifier to be most effective? For an air purifier to work effectively, it must have sufficient space to bring air into the purifier and push clean air out into the room. Smart Air ran tests on the Blast and Blast Mini to determine the ideal distance from a wall that would allow for adequate airflow. They found that these purifiers need about six inches of space from a wall to work at 100 percent effectiveness.
Does its location in the room matter? Smart Air ran studies with an air purifier in one location, using air quality monitors to determine its effectiveness in other parts of the room, both near and far from the purifier. They found that as long as the air purifier was powerful enough for the room’s size, the differences in air quality at the various locations in the room were minimal.
If you’re in the market for an air purifier for your home, keep your eyes peeled for common misconceptions about HEPA air purifiers and filters. Smarter HEPA has the scientific knowledge necessary to debunk this misinformation and provide reliable data to put your mind at ease.
