While sweltering summer days in front of the fan might not be ideal for those of us with allergies, winter is often the worst season for indoor air quality. Burning logs in the fireplace, sealing out cold air, and firing up dust-caked heating systems can all make it hard to breathe.
Thankfully, an air purifier can help relieve allergies and other respiratory issues. Learn about how air purifiers can improve the air quality throughout your home to keep you healthy throughout the snow-flurried days.
How Air Purifiers Work
While an air filter is built-in to your HVAC system, an air purifier is a stand-alone appliance that removes airborne contaminants (bacteria, pollen, mold spores, pet dander, etc.). Air purifiers also help eliminate unpleasant odors, neutralize smoke, and trap dust (this device helps keep home cleaning manageable rather than serving as a replacement).
Most air purifiers use mechanical air filters, which suck air particles into an internal fan, trapping them as the remaining air passes through the machine. From there, purified air circulates back into the room. This process repeats several times per hour, and the appliance is most effective if left constantly running.
Now let’s break down the different types and components of air purifiers.
The prefilter is the first barrier that dirty air passes through. Prefilters catch large particles like human hair and pet fur before they reach the purifier’s main filter.
Smaller particles that evade the prefilter then pass through the main filter. The gold standard for air purifiers, recommended by the EPA and the American Lung Association, is a high-efficiency particulate air (HEPA) filter. This pleated mechanical air filter is designed to remove at least 99.97% of dust, pollen, mold, bacteria, and any fine airborne particles down to a size of 0.3 microns.
Activated Carbon Filter
Some air purifiers have an additional filter to remove odors, vapors, and gases. These are usually made of activated carbon, which is a porous medium that can absorb pollutants that pass through it.
Activated carbon filters work best for smoke, cooking gases, paints, and chemicals known as volatile organic compounds (VOCs). A variety of materials and home products contain VOCs, including varnishes, caulks, vinyl flooring, and cleaning products.
This method of indoor air cleaning doesn’t use any filters. When air flows through the device, the appliance emits negatively charged ions into the air that latch onto pollutants. This bond increases the density of the airborne particles. The ion pair, now too heavy to stay in the air, settles on the ground. The homeowner can then vacuum the particles off the floor or wipe them from surfaces.
UV Light Air Purifiers
Some portable air purifiers have ultraviolet lamps to sterilize the air as it passes through, removing similar particles as an HEPA filter. The specific form of light used in this filtering device is UV-C, one of three forms of ultraviolet light. UV-C disinfects your air by breaking the genetic code of microscopic organisms. This method of removing airborne bacteria and viruses is known as germicidal irradiation.
The drawback to UV-C filters is that air needs to stay in the purification chamber long enough for UV-C light to work, which is longer than it would take particles to pass through a typical purifier. Air purifiers that use UV lamps can also produce ozone, a lung irritant, so you’ll want to be extra vigilant about the quality of the manufacturer.
The EPA cautions against relying on UV light without also using a HEPA filter, since dead or deactivated particles can still pose a health risk. Additionally, HEPA filters trap allergens, dust, mold, and other airborne particles that UV-C lights do not catch.
Choosing the Right Size
The filter size needs to be appropriate for the space it will work in. If the filter is too small for the room, then it won’t be able to adequately sanitize the air. However, placing a large purifier in a small room is overkill that runs up your electricity bill.
When choosing an air purifier, a critical metric you’ll want to look at is the device’s clean air delivery rate (CADR). This rating tells you how effective the purifier is at filtering a specific room size. The higher the number, the larger the space the device is expected to clean.
CADR ratings are assigned by the Association of Home Appliance Manufacturers and generally contain three numbers: one for smoke (the smallest particle), one for dust and one for pollen (the largest particle). The EPA has set minimum CADR ratings that it recommends for various room sizes.
A clogged filter is an inefficient filter, which is why you should change your filter every 3-6 months for optimal performance. However, for those suffering from asthma or allergies we recommend increasing this frequency to every 30-60 days. Many models also come with an indicator light, so you know when it’s time to change the filter.
For those who suffer from allergies or live with pets, they would most benefit from having the machine running all day and night. Look at noise levels (listed in decibels) in product specs to find a model that won’t disturb anyone in their sleep. For reference, a very quiet air purifier (barely louder than rustling leaves) is 15 dB while a standard air purifier on a low setting is 36 dB.
The Bottom Line
While there is no one-size-fits-all solution for an air purifier, you can easily find one to fit within the boundaries of maintenance, home needs, and budget. Investing in an air purifier is one of the best decisions a homeowner can make to maintain a clean, healthy space. It’s time to breathe freely.