Dust/pollen/smoke removal: How well models cleared air of fine clay dust and cigarette smoke; performance of portables is at their highest and lowest speeds. Ones that scored well for dust removal should perform comparably for pollen.
Noise: Based on instrument measurements with a portable model running at its highest and lowest speeds.
Summary: This portable air purifier from Whirlpool is primarily filter-based and has a filter indicator, a programmable timer, and 4 speeds. It's designed for floor or tabletop use in a large room.
Air purifier buying guide
Getting started
Before you buy an air purifier, try some simple, common-sense steps to reduce indoor air pollution. Begin by vacuuming often, banning smoking indoors, minimizing use of candles and wood fires, and using exhaust fans in kitchen, bath, and laundry areas. Test your home for radon gas, which can cause lung cancer (test kits cost about $15). Don't store chemicals, solvents, glues, or pesticides in your house. Minimize the risk of deadly carbon monoxide gas by properly maintaining and venting heating equipment, wood stoves, fireplaces, chimneys, and vents--and by installing carbon-monoxide alarms on all levels of your home. And don't idle your car, run fuel-burning power equipment, or light a barbecue grill in your garage, basement, or in confined spaces near your home.
The better air purifiers do especially well at filtering pollutant particles such as dust, tobacco smoke, and pollen. Volatile organic compounds (VOCs) and other types of gaseous pollutants, however, are another matter. Some portable models with carbon pre-filters are claimed to filter VOCs, known respiratory irritants that arise from adhesives, paints, and cleaning products. But the Environmental Protection Agency warns that such filters are specific to certain gaseous pollutants, not for others, and that no air purifiers are expected to remove all gaseous pollutants found in the typical home. Carbon filters also must be replaced often, typically every 3-6 months, or they stop working--and can even, when full, release trapped pollutants back into the air. The safer course: Heed strict product-label warnings such as "use only in well-ventilated spaces."
Air-purifier models with an electrostatic precipitator remove pollutant particles by charging them as they pass through and collecting them on an oppositely charged metal plate or filter. In the process, they produce some ozone as a byproduct. You'll also find dedicated ozone generators, which produce relatively large amounts of this gas by design. While ozone in the upper atmosphere protects us from the sun's ultraviolet rays, ground-level ozone is an irritant that can worsen asthma and compromise your ability to fight respiratory infections. We believe that air purifiers that emit even small amounts of ozone are a poor choice if someone in your household has pulmonary problems or allergy symptoms. We also suggest that you avoid dedicated ozone generators entirely, given their high ozone emissions.
The very best portable models we tested were effective at cleaning the air of dust, smoke, and pollen at their highest or lowest speed. For whole-house purifiers, our recommended models did best at filtering dust and pollen without impeding the airflow of forced-air heating and cooling systems. The worst models weren't terribly effective at any speed.
How to choose
If you want a purifier and don't have a forced-air system, consider a large portable. In addition to removing more particles at high speeds, the better large models still did well at lower, quieter speeds.
Weigh features carefully. Most air purifiers have an indicator that tells you when first to clean or replace the filter to maintain efficiency. But some indicators turn on based on length of time the unit has been running, not how dirty the filter is. Skip odor-removal features. In past tests it took up to an hour for them to make a difference--when they did anything at all.
And the certifications on the box? All tell how well a model filters particles at its highest speed. The certifications all also allow up to 50 parts per billion of ozone, a respiratory irritant. We advise against using models that produce any ozone, even if they are effective cleaners.
Check an air purifier's efficiency rating
If you still want one, use this air-purifier guide to choose. The Association of Home Appliance Manufacturers certifies most room models as part of a voluntary program that includes appropriate room size and maximum clean-air delivery rate (CADR), a measure of cleaning speed. We judge a CADR above 350 to be excellent and below 100 to be poor. Choose a model designed for an area larger than yours for better cleaning at a lower, quieter speed. Many whole-house filters list a minimum efficiency reporting value (MERV), developed by the American Society of Heating, Refrigerating, and Air-Conditioning Engineers. The top performers in our tests typically had a MERV higher than 10.
Types
There are two basic types of air purifiers. Room models, which are most heavily promoted, can be moved from room to room. Whole-house models are built into the ductwork of a forced-air heating or cooling system and, as their name implies, filter the air in the entire house.
Room air purifiers
These are the only option for a home that doesn't have forced-air heating or cooling. Room air purifiers cost much less than whole-house models. Most room air purifiers weigh from 10 to 20 pounds, have a handle, and stand on the floor or on a table, while heavier models might have wheels. Some room models use a high-efficiency particulate air (HEPA) filter, which can capture ultrafine particles. Most HEPA filters need to be replaced annually, an expense that might approach the cost of the air cleaner (A few air cleaners are now available with cleanable HEPA filters.) Room models that use either electrostatic-precipitator or ionizer technology produce some ozone, a lung irritant. And they might soil the walls by depositing some pollutant particles on them.
Dedicated ozone generators
These are a subcategory of room models. Unlike electrostatic precipitators, which tend to emit small amounts of ozone as a byproduct, these niche products produce large amounts of ozone by design. According to manufacturers, that is to reduce allergens such as dust, smoke, pollen, germs, and mold. Ozone, however, is a serious health concern, prompting the State of California to ban the sale of ozone generators (and other air purifiers that emit more than 50 parts per billion of ozone) from the general market.
Whole-house air purifiers
This type is a reasonable choice if your home has forced-air heating. But built-ins can be expensive to buy, and they must be installed professionally in the ductwork of your heating system and most need to be wired into your home's electrical system. Most of the built-in air cleaners we tested did an excellent job of removing dust and smoke particles from the air. Some use a high-efficiency filter. Those that use an electrostatic precipitator produce some ozone, and they might soil the walls by depositing pollutant particles on them.
Whole-house air filters
Whole-house air filters These inexpensive alternatives to a whole-house built-in unit replace the existing furnace filter in your forced-air heating or cooling system. You simply slip out the old filter and slide in the replacement. But those we tested worked much less effectively than the built-in whole-house models, especially in clearing smoke. Some are conventional fiberglass filters; others
Features
Whole-house air filters generally include a range of standard sizes, with some that adapt to fit different-size filter-box or return-air openings. Room air cleaners usually use a fan to pull air into the unit for filtration. But don't expect a wide array of bells and whistles. Here are the air purifier features to consider.
Fan
Most room air cleaners use a fan to suck in air. Those without a fan run more quietly, but those we've tested worked poorly.
Servicing indicator
A clogged air cleaner works inefficiently. You should remove and wash an electronic precipitator's collector-plate assembly every month or so. (You can do it in the sink or tub or put it in a dishwasher.) In most room and whole-house models that use an electrostatic precipitator, and in whole-house models that use a HEPA filter with ionizing circuitry, an indicator light lets you know when it's time to replace or clean the filter.
Dust sensor and air-quality monitor
In some room models, these raise or lower the fan speed automatically. But we were unimpressed with those we tested. They didn't kick in until pollutant levels were high, and then they shut off before the levels dropped sufficiently.
http://www.consumerreports.org/cro/appliances/heating-cooling-and-air/air-purifiers/room-air-purifier-ratings/models/overview/whirlpool-whispure-ap51030k-99029938.htm
