What to look for when buying air purifiers for your home

If you have allergies or asthma, or are sensitive to pollution, you may have considered purchasing an air purifier to clean the air inside your home. Now, with smoke from destructive wildfires still burning in Northern California affecting people as far as 100 miles away, even those without specific health concerns are thinking about ways to improve indoor air quality. But with so many types of filtration systems on the market (and prices ranging from $100 to nearly $1,000), it can be hard to know where to begin. Check out this quick guide to home air purifiers to figure out which are worth the cost.

Why use an air purifier? Indoor air pollution comes from a combination of particulate matter (dust, mold, pet dander and particles from smoke and cooking stoves) and gaseous pollutants (vehicle exhaust, smoke and chemical fumes) and can be far worse than the pollution outside, simply because it has no way to dissipate.

Those who suffer from asthma or allergies can be especially sensitive to air quality, and using an air purifier could be helpful, together with other methods of keeping out pollution and allergens.

Purify your home, not just the air. Air purifiers can do wonders for removing particulate matter from the air; the problem is that dust, pet dander and the like don’t stay in the air for long. Allergens drift to the ground and become embedded in rugs and soft furnishings — places an air purifier cannot reach. A combination approach will reduce indoor air pollution and allergens more than any one method alone. Here are a few strategies to try:

○       Remove wall-to-wall carpeting; go for easy-to-clean hard flooring and washable area rugs.

○       Vacuum and dust with a microfiber cloth regularly.

○       Ban smoking in and around the house.

○       Do not use a fireplace.

○       Do use the exhaust fans over the stove and in the bathroom.

○       Establish a no-shoes policy.

RELATED: Get an Exhaust Fan for the Bathroom

What to do if you are affected by wildfire smoke. Depending on wind direction and other atmospheric conditions, smoke from wildfires can drift 100 miles or farther from the source of the flames. If you are affected by wildfire smoke (but not in an evacuation area), the Centers for Disease Control recommends staying indoors when possible, with windows, doors, and fireplace dampers closed. Here are a few more things you can do:

○       Use your central air-conditioning system if you have one, but keep the fresh air intake closed to prevent smoke from getting inside.

○       Clean or replace the HVAC filter more frequently as long as you are experiencing smoky conditions.

○       Cut down on activities that contribute to indoor air pollution, including burning candles and using a fireplace, wood stove or gas stove.

○       Avoid vacuuming, as this can stir up large particles that have settled.

○       If you do not have an in-duct air filtration system, it can be helpful to use a portable air purifier with a high-efficiency particulate air (HEPA) filter to remove some of the particulate matter from the air.

○       If you have a medical emergency from smoke, you should call 911 or go to a hospital emergency room immediately.

How air purifiers work. There are a few different types of air purifiers on the market, and not all of them are especially effective or safe. It is important to know what you are buying, so read the fine print on your air purifier before purchasing. The main thing to check is how the purifier cleans the air. It will likely use one or more of these methods:

○       High-efficiency particulate air (HEPA) filter: This is the most common and one of the most effective methods available.

○       Activated carbon: Usually used with a HEPA filter or another filter, activated carbon can help reduce pollution by attracting some chemicals, which bond to the surface of the carbon.

○       Ultraviolet germicidal irradiation (UVGI) cleaners: These use a UV light to kill viruses, bacteria, allergens and some molds. UVGI cleaners may not reduce allergy or asthma symptoms, because typical home cleaners have limited effectiveness.

○       Electrostatic precipitators: Particles entering the purifier are given a charge and then trapped on oppositely charged plates. These machines create a small amount of ozone, which is a lung irritant and pollutant itself, so this type of purifier is probably best avoided.

Not effective as an air purifier at all, ozone generators are being marketed as air cleaners, but they actually add lung-irritating ozone to your home, which can be hazardous. The Environmental Protection Agency does not recommend buying ozone generators.

When to choose a whole-house air cleaner: If you have a heating, ventilation and air-conditioning (HVAC) system in your home, you have the option of having a whole-house air cleaner installed right in the ductwork. The benefits of a whole-house system are that all of the air is cleaned and there are no bulky appliances to deal with. In-duct systems are expensive, and they must be professionally installed and maintained.

When to choose a portable room purifier: Room purifiers are a good choice for smaller spaces, and multiple units can be used to clean the air even in a larger home. They are portable, so they are a good solution for renters, and cost anywhere from $100 to $1,000 per unit.

Get to know the rating systems. For in-duct air filters, look for the minimum efficiency reporting value (MERV) to tell how efficiently they pull particles from the air. MERV values range from 1 to 20; a system rated 7 or higher is about as effective as a HEPA filter. True HEPA filters, which have MERV values of 17 to 20, are not typically installed in HVAC systems. However, some newer homes may be specially designed with in-duct HEPA filtration.

When shopping for a portable air purifier, look for a clean air delivery rate (CADR) of at least 250, but the higher the better. This is a voluntary system developed by the Association of Home Appliance Manufacturers (AHAM), so not all appliances have a CADR.

An Energy Star label on any air purifier indicates better energy efficiency but does not necessarily mean it is more effective — so also be sure to check the MERV or CADR rating.

Want to be really sure your air purifier is doing its job? Look for the AHAM Verifide mark on your portable air cleaner, which indicates that the manufacturer’s claims have been independently tested and certified.