Pet dander, dust mites and mold—oh my! The average home is teeming with particulates that can trigger allergies and aggravate asthma. Even those without allergies or other breathing difficulties may be bothered by the air inside our dwellings, simply because there's a lot of stuff in there that isn't air. For many, air purifiers are a welcome addition to the home appliance arsenal.
Types of Air Purifiers
Purifiers are categorized not just by the technology they use to clean air but also by the types of filters they use. As a result, there's a bit of overlap in how they're broken down. Here's a quick rundown:
High Efficiency Particulate Air (HEPA). These popular air purifiers (and filters) are loved by those with allergies and other sensitivities because they remove 99.97 percent of 0.3-micrometer particles, including pollen, mold spores, dust and animal dander. Keep in mind that the bigger the unit, the more effectively it will remove particulates from the air.
Ion generators and ozone generators. Both ion and ozone generator air filters emit charged ions into the air, which attach to impurities such as dust. The ion-bonded particulates then cling to any available surface, effectively taking them out of the air (but also possibly creating dirty spots on walls and other surfaces). The main disadvantage to ion and ozone generators is a big one; they emit ozone, which can be an irritant to the lungs. The American Lung Association actively warns consumers against any air purifier that emits ozone. In other words, steer clear of these.
Electrostatic precipitators. These air purifiers work using the same principal as ion and ozone generators, but they capture impurities on special collector plates. Be warned, however; many electrostatic precipitators emit ozone too. Some testers argue that all of them produce ozone, despite manufacturer claims, so if you choose this route, research each individual model carefully.
Charged media. Charged media air purifiers are just like electrostatic precipitators, but replace collector plates with fiber filters. Like HEPA filters, they trap very small particles — down to 0.1 microns — but filters may need to be changed often. Some charged media purifiers produce ozone, but models that do not are available. Check product literature carefully.
UV air. These air purifiers use a UV lamp to eliminate viruses, bacteria and germs, and they are generally used in labs, hospitals, kitchens and even daycare centers. Many homeowners like them because they're great at getting rid of mold spores (although HEPA filters do quite well too). Remember that they don't eliminate particulates; if you need one that does — and is also antibacterial and germicidal – there are purifiers that use treated HEPA filters to kill the nasties.
Activated carbon. Although these are sometimes described as a type of air purifier, activated carbon filters are normally used in conjunction with other systems. They are primarily used to trap chemicals and gases, which are too small for HEPA filters to catch. They're great at removing odors too.
Key Features
Here are some terms and features you'll encounter in your quest for clean air:
Clean Air Delivery Rate (CADR). CADR represents how many cubic feet of clean air is delivered per minute, but what do those numbers mean? It all depends on the size of your room. To calculate CADR, follow this simple formula: square feet of area x .75. The resultant number is the CADR you want.
Air Changes per Hour (ACH). ACH tells you how many times an hour all the air in a room is completely replaced by purified air. The most common range is from two to six. This number is closely related to CADR because it is determined by calculating the square foot of the area by the CADR, and then dividing by 60. Don't worry, you don't have to do the math – most product literature will provide both numbers for you.
Fan speeds. The faster the fan's speed, the higher the ACH —and the louder the unit. Air purifiers run all the time, and a noisy one might drive you crazy. Look for a unit with multiple fan speeds, so you can ratchet down the noise levels when necessary. Super quiet models are available, but you'll pay a premium for them. Your best bet is to go to a store that specializes in air purifiers so you can see (and hear) different models in action.
Electronic controls and sensors. Some units come with sensors that tell you when the fan needs to be replaced, monitor air quality and more. These features can all be very nice, but they also add quite a bit to the purchase price. Determine which features you need, and shop accordingly.
How to Choose
To repeat the above advice, stay away from any air purifier that generates ozone. Your lungs will thank you, and you'll find that the playing field has been considerably narrowed. This is a good thing because a lot of product literature about air purifiers tends to consist of one-upping the competition.
Air purifiers come in every permutation imaginable, mixing up types of systems with different filters or using multiple filters in a single unit. Instead of looking at combination units as a whole, consider your needs. Do you have allergies? Is mold a problem in your area? Do you have pets that make the house smell less than pleasant? Is your chief concern volatile organic compounds, such as those found in cleaning fluids? There's also the question of size. Do you need one room purified, or your whole house? Once you've identified your specific needs, you can search for the type and size of the air purifier that is right for you.
Air purifiers range widely in price, with small units going for under $100 and whole-house models for several thousand. Again, consider your needs and choose accordingly. Also, research how much replacement filters cost for each model you're considering. Expensive filters can often be a deal breaker, especially if there are multiple types of filters in the unit. Finally, consider how much energy the unit consumes, particularly because your air purifier will probably be running continuously. Not sure from the box? It's easy. Multiple the volts listed by the amps. The result is wattage.
