Tip of the Day: Take the work and injury out of fall cleanup

As I lay in bed last Sunday morning recovering from a day spent removing my air conditioners, my colleague Steven H. Saltzman had already started on his fall yard cleanup and wasted no time blogging about it.

Don't feel guilty if you've yet to start your own seasonal cleanup. In this case, procrastination is not a bad thing--use the time to review our best lawn-care products.

Plus, you'll be able to heed this expert advice from the Consumer Reports Health blog to avoid raking-related and other injuries. And follow these tips from Silvana Fix, D.P.T., a doctor of physical therapy with Spine and Sports Rehab in Fairfield, Connecticut.

• Before you start working, "a brisk walk for about 10 minutes is a good general warm-up," says Fix. To stretch your back, "Stand with your feet shoulder-width apart and bend backward five to 10 times before returning to a full upright position," says Fix.

For your quadriceps, bend your right leg, grab the ankle with your right hand, and gently pull your leg toward your buttocks. Hold that for a count of 10 or 20. Repeat with your left leg. Be sure you're near a wall or tree and on flat ground so you can maintain your balance.

Fix also recommends this easy chest-and-shoulder stretch: Stand with your feet shoulder-width apart, clasp your hands behind your back and gently bring your hands away from your back. Hold for a count of 10 and repeat two or three times.

• When you rake, "Keep your wrists in a neutral position, with no bending. A rake that has a bent or side-mounted handle can help here," says Fix. She adds that good body mechanics are important: "Place one foot ahead of the other, keep your back straight, and rake the leaves while taking small steps backward and keeping your arms close to our body."

As you work, avoid stooping or bending forward, twisting your back, and overreaching with your arms, and keep your feet planted firmly in one place on the ground, according to Fix, who notes that you should stretch again when you're done and consult a medical professional if you pain lingers.—Gian Trotta

Essential information: Remember, it's important to get rid of leaves, especially under your deck. Piles of leaves are an open invitation to mice, which can carry Lyme disease and hantavirus, and other pests to set up warm winter homes. Our fall lawn-and-yard checklist will help your yard looks its best next spring. Autumn is an especially effective time to fertilize some lawns. Don't hesitate to fall back on mechanical help to get the job done, including the latest leaf-bagging lawn tractors, cordless and gas-powered leaf blowers, and string trimmers.

Tip of the Day: Clean your ceiling fans

My approach to housekeeping is akin to the “If a tree falls in the woods and no one is around to hear it, does it make a noise?” conundrum: I don’t mind the weekly ritual of cleaning my house, but I do cut corners where I can—if I can’t see the grime, then it doesn’t count.

I’ve often taken this tack when with ceiling fans. From below, I usually don’t notice the dust and grime on my fans. But when I recently climbed a stepladder for a closer look at the one in my bedroom it was clear I had to clean the fan. The dust and grime weren’t overwhelming—yet. So I decided to tackle this simple task before it could turn into a messy ordeal.

When you’re cleaning your ceiling fans, first find out what steps the manufacturer recommends, and then consider our experts’ suggestions below. Remember, clean a fan only after you’ve turned it off and the blades have come to a full stop. And cover the floor (and furniture) beneath the fan with a drop cloth. If the blades are lightweight, handle them with care.

• Use a long-handled, ceiling-fan duster to remove dust. (These special round brushes are sold at hardware stores and home centers.) The blade fits in the inner part of the duster and will clean both sides of the blade at the same time.

• If your fan is equipped with a light, gently dust the fixture (and the bulb, if it’s exposed) with a soft cloth.

• To remove accumulated grime, wash the blades and fan housing with a damp cloth sprayed with an all-purpose cleaner or dipped in a solution of water and mild detergent. (Learn how to make your own household cleaners.)

• Then wipe the blades with a cloth dampened with water to remove detergent residue.

• Finally, dry the blades thoroughly— dampness attracts dust.

Be careful when you’re reaching up to clean the blades if you don’t have a brush. If you need to buy a ladder for this and other household chores, see our review of ladders.—Kimberly Janeway

Essential information: Read our latest report on ceiling fans to choose the right models for your home. And learn how to stay cool without running up your utility bills. Use our Home Improvement Guide interactive to take a room-by-room tour of the top-rated appliances and most cost-effective improvements you can make to your home.

Buying Advice: Portable air conditioners

A portable air conditioner that you can roll from room to room might appeal to you if your window space is limited or if you live in a building where regular room air conditioners are prohibited.*

But our past tests of three large portable air conditioners, each with a claimed cooling capacity of 10,000 Btu/hr., showed that they delivered less relief from the heat than their manufacturers touted. What’s more, these $400 to $500 appliances were pricey, especially compared with the window air conditioners we recently tested. (Use our free calculator to determine what size air conditioner(s) you need.)

The portable units we tested had a single exhaust hose that routed air from inside the room over the air conditioners’ condenser coils and finally to the outside. A typical portable air conditioner comes with a low-profile vent adapter bracket that you place in a double-hung window to allow the hot, humid air to  exhaust (generally no tools are required for this installation).

While portable air conditioners might be convenient, those we tested delivered only about half of their cooling capacity—that means they operated with an energy-efficiency ratio (EER) of about 5 or 6. Compare that with the minimum EER of just under 10 for the window air conditioners we’ve recently test (we tested window models with an EER as high as 12).

Why are portable units are so inefficient? The air they exhaust to the outside comes from inside the room you’re trying to cool (as well as from adjacent spaces). The energy used to cool and dehumidify the air is essentially wasted since it gets sent out the vent hose.

What’s more, this setup means that warm, humid outside air will leak back into the room, and that air must then be cooled and dehumidified. The result: inefficient operation.

Some portable air conditioners have two hoses—one that brings in air from the outside to cool the condenser coils and another to exhaust that air back to the outside. (We haven’t yet tested models with this configuration.) This setup mimics the process of a traditional window air conditioner, so these models should come closer to delivering their stated Btu/hr. ratings.

However, moving the air through these hoses can waste energy, so their efficiency levels are typically lower that those of typical conventional window air conditioners.

*If air conditioners are prohibited in your building be sure you know the reason why. For instance, older buildings with older electrical wiring might ban them for safety reasons.

In this neighbor dispute, air-purifier maker clears the air

They say good fences make good neighbors, but in one New York City apartment building, an air-filtration system was key to keeping the peace.

The dispute became known last winter after news stories reported that a couple, lawyers who live in an upscale Upper West Side apartment building, had sued a neighbor on their floor because cigarette smoke was wafting from her condominium into the common hallway. The plaintiffs have a young son whose health, they claimed, was being affected by the secondhand smoke.

New Yorkers love a good real-estate dispute, and this one had the makings of a reality-TV classic (the defendant had also been accused of having her dog urinate on a the plaintiffs’ stroller). But the parties settled the matter out of court, thanks in part to the third-party efforts of Aerus, which makes vacuums and air purifiers.

Shortly after the suit was filed, Aerus offered to install an air-filtration system for free in the defendant’s apartment to help capture the smoke from her cigarettes. In a New York Times article, Joseph P. Urso, chief executive of Aerus, said the filtering system was instrumental to reaching a settlement.

We’re currently working on a story on neighborly disputes, and would love to hear your stories about any nuisances you’ve had to deal with, including issues related to topics like noise, fences, trees, boundaries/property lines, safety, and esthetics.

If you have a compelling tale to tell, send us an e-mail with all the details. As always, we’ll respect your privacy—read our privacy policy—and will keep your information confidential. Please indicate if you’re willing to be contacted by a reporter working on this story.—Daniel DiClerico

Essential information: When you’re in the market for an air purifier, read our latest report on these devices and follow our advice to determine whether you need one and to choose the right model for your home. Ratings of room and whole-house models are available to subscribers.

Tip of the Day: Dehumidifiers can keep your home comfortable and prevent mold and mildew

Deploying a dehumidifier in damp areas of your home is an easy way to not only boost your comfort but also to prevent a number of problems, including sickness, mold and mildew growth, and damage to your home and its furnishings.

My own “FOBFU”—find out by fouling up—lesson illustrates why it’s smart to use a dehumidifier. I stored a bunch of camping equipment in my basement, which tended to be very humid. When I went to retrieve a sleeping bag for a camping trip, I found it ruined by the damp environment. I immediately went online to read our recent report on dehumidifiers. It turns out you can get a capable model for about $140 dollars—and perhaps even less if you combine it with a rebate or tax credit by buying an energy-efficient version.

Most dehumidifiers have features such as a built-in timer, which can be useful in some situations, and a hose-attachment point to drain the water, eliminating your having to empty a reservoir. One model even comes with a pump and plastic tubing that sends the collected water out a window or up to a slop sink or other high drain. Other factors to consider when buying a dehumidifier include energy use, noise, performance in brownout conditions, and the ability to automatically restart after a power blackout.

I’ve learned my lesson. My new dehumidifier is now humming away down the basement, keeping my camping gear in good shape.—Gian Trotta

Essential information: Learn how to alleviate other basement-moisture problems. To keep the rest of your home comfortable this summer, read “How to Keep Your Cool” and our latest reports on room air conditioners and ceiling fans.

Protect Your Investment: Maintain your air conditioner

Air conditioners can be energy gluttons, but if you keep your air-conditioning in tiptop shape, you can decrease how much energy your cooling system uses this summer and maximize its efficiency. Consider that a dirty, clogged filter reduces airflow, can lead to operational problems like coil freeze-up, and in general makes your system work harder.

Best of all, the work is easy and won’t cause you to break a sweat.

Installation steps
• Vacuum any debris from the indoor and outdoor coils with an upholstery-brush attachment before you install your room air conditioner. Take care not to damage or deform the soft fins.
• Seal the perimeter of the installed unit with new weatherstripping, if needed.

Monthly jobs during cooling season
• Take out the filter and vacuum off debris. Wash it in warm, soapy water. Rinse the filter let it dry completely, then reinstall. If the filter is very dirty or your usage increases significantly, clean the filter more often.
• If dirt and debris have bypassed the filter, you will need to remove the front panel and vacuum dust and debris from the coils.
• Replace a deteriorated filter.

Tips for a central-air unit
• Call in your service contractor if you haven’t already. The pro should change all filters; clean and flush the coils, drain pan, and drainage system; and vacuum the blower compartments. Additionally, the service contractor should ensure that the system is properly charged with refrigerant, that there are no leaks, and that all mechanical components are working properly. Our experts also recommend that you:
• Clean or replace the filters monthly or as needed. Also clean the grilles.
• Clear debris and dirt from the outdoor condenser coils. And keep vegetation at least two feet away from the unit.
• Check if there’s a blockage in the pipe that drains condensed water from the indoor unit.

At the end of the cooling season, follow the expert advice in this Q&A from the Home & Garden blog.— Kimberly Janeway

Essential information: Read our latest report on air conditioners, including Ratings of dozens of models (available to subscribers). Also find out how to use less air conditioning this summer and read our review of ceiling fans. And use our Home Improvement Guide interactive to take a room-by-room tour of the top-rated appliances and most cost-effective improvements you can make to your home.

Q&A: Which direction should the blades on my ceiling fan rotate?

My ceiling fan has a switch that reverses the direction the blades rotate. How do I know which direction to run the fan during warm- and cold-weather months?

During warm weather, you should run the fan so that the breeze blows downward. This wind-chill effect—the same cool breeze you feel when you roll down the window in a moving car—will cool you.

Many ceiling-fan manufacturers and various Web sites out there suggest that you run the ceiling fan so that it blows in the opposite direction—upward—when the weather is cold and the heat is on in your home. The idea is that the fan mixes the warm air collecting at the ceiling and moves it back down to the perimeter of room, creating a higher average room temperature and less need for heat. (All of the ceiling fans we recently tested have a switch that you flip to reverse the motion of the blade.)

 

But in our past tests, we found that the draft caused by the fan can have a chilling effect on people in a room—and lead to higher thermostat settings and more energy use. So we recommend that you not bother to reverse the motion of your fan—just leave it off during heating season. Note that there might be some situations where reverse operation would be be beneficial, such as in a room with a wood stove running or a very high vaulted ceiling.

If you’re looking to lower your energy bills during cooling season, use ceiling fans and turn off your air conditioning or turn up the temperature on your A/C a few degrees and let the fan go to work. Remember that ceiling fans cool you and not the space you’re in, so turn them off when you leave the room for an extended time so as to not waste electricity.

When shopping for a ceiling fan, you’ll find old-style models that conjure memories of Bogart and Bergman in Casablanca and versions that are modern twists on an invention that first appeared in the U.S. in the 1860s. In our latest report on ceiling fans, we found that while the pricier fans did have fancier finishes, they didn’t necessarily provide better performance. What’s more, most fans performed similarly in our air-movement tests.

Essential information: See our advice on staying cool this summer without cranking up the A/C, and share your tips for keeping comfortable, in our forums.

Vintage Consumer Reports: Ceiling Fans

With ceiling fans, “you can go from breeze to bluster to benign zephyr,” we wrote in our July 1982 report on summer cooling. “Even the most profligate model,” we noted, “would cost only pennies a day to run.”

Ceiling fans haven’t changed much over the past 26 years. (The top fan shown is from 1982; the bottom one, from our July 2008 story on ceiling fans.) Although they cost slightly more to run today than they did during the early part of the Reagan era, ceiling fans can decrease energy consumption and save you money, but only if you use your air conditioner less or set it to a warmer temperature and rely on the cooling breeze from the fan. (See our latest report on and review of air conditioners, and learn more ways to keep cool this summer.)

“A ceiling fan can conjure up an exotic feeling even in a raised ranch in the suburbs,” we wrote in the 1982 article. If a virtual experience isn’t enough, you can put the money you’ve saved toward a real getaway. Read our Ratings-based reports on airlines and hotels.

Brand new on ConsumerReports.org

Check out the latest Appliances and Home & Garden product reports and reviews on ConsumerReports.org:

Room air conditioners, which features Ratings of more than three dozen models and expert advice to lower your utility bills this season.

Ceiling fans, which includes expert buying advice.

Deck stains, which provides Ratings of fully tested 16 opaque, semitransparent, and clear stains.

Deck materials, which includes Ratings of wood, composite, plastic, and aluminum decking products as well as tips for keeping your deck safe.

Claim Check: Venta-Airwasher “Humidicleaner”

The claim. The Venta-Airwasher—a “humidifier & purifier—two in one," according to the manufacturer’s Web site—is supposed to trap particles as small as 10 microns while adding moisture to the air. Four models of these German-made products are available for rooms of different sizes: LW 14 (1.2-gallon capacity, $200); LW 24 (2-gallon capacity, $300); LW 44 (3-gallon capacity, $400); and LW 84 (6-gallon capacity, $1,440).

A Venta-Airwasher uses a series of rotating plastic discs to clean the air and add moisture to it. Those discs, mounted on an axle that constantly rotates, dip in and out of a water-filled reservoir. As the wet discs emerge from the reservoir, a built-in fan evaporates the water on them, boosting humidity in a space. Particles in the air are supposed to stick to the discs, then wash off as the discs pass through the reservoir again.

The check. We tested the LW 14 and LW 44 (shown) models as we usually test air purifiers, by measuring their clean-air-delivery rate with the fine dust and cigarette smoke (0.1 to 3 microns) that are of more concern to people with respiratory problems. To test their humidifying chops, we placed each device in a sealed chamber and let it run overnight, recording the humidity level in the room.

The Consumer Reports take. The claim of ridding the air of particles as small as 10 microns is kind of a nonstarter: A 10-micron or larger particle is so big that it's unlikely to remain aloft in the air for long.

Both models we tested proved no better at removing dust and smoke than no air purifier at all. They were, however, efficient at adding moisture to the room. Note that they lack a sensor and controls to let you set a humidity level. Without those features, humidity could rise too high and contribute to mold and mildew growth. What’s more, the Venta-Airwashers are pricey and require you to buy water additive and cleaning solution—a cost of about $90 per year.

Essential information: Watch this video to see how we tested the Venta-Airwasher. Before you buy any air purifier, read the expert advice in our latest report, and find out how well some models eliminate odors and learn how much maintenance your air purifier might require.

Inside CR Test Labs: Maintaining an air purifier

How well you maintain your air purifier will directly affect its performance over time

Do you remember the last time you cleaned the filter in your range hood or replaced the filter in your furnace or air conditioner? If no, you’re not alone. As part of our testing for “Filtering the Claims,” we wanted to see how air-cleaning performance would changes as an air purifier’s cleaning media became loaded with dust, smoke, and other airborne particles. We also hoped to determine if you  need to replace filters as manufacturers suggest or if doing so is a waste of money.

To measure how cleaning performance changes over time, we tested the Friedrich C-90B plate-type electrostatic precipitator, or EP, air purifier and the Whirlpool Whispure AP45030S and IQAir HealthPro Plus HEPA-filter models. We ran these air purifiers nonstop for one year in a very large commercial space whose air we expected to contain dust and smoke particles.

We also rearranged the devices in the space to ensure each machine experienced the same conditions. And throughout the year at regular intervals, we brought the purifiers back to our labs to gauge their cleaning performance.

While the performance of the two HEPA models declined gradually and at a similar rate, that of the Friedrich (shown) fell more abruptly—about 20 percent in one month. It took the entire year, including not changing the prefilters at the manufacturers’ recommended intervals, for the HEPA models to decline that much.

However, because the Friedrich’s initial performance was the best of this group, after a month its absolute performance, indicated by its clean-air-delivery rate, or CADR, was still higher than that of the IQAir when new—265 compared with 237. It took about another month without cleaning its plates before the Friedrich’s CADR dropped below 237. What’s more, after we cleaned its prefilter and collection plates, the Friedrich saw its CADR return to its original high value of 335, confirming the importance of maintenance.

The bottom line: You need to maintain your air purifier if you expect it to keep cleaning the air in your home. Our testing supports the typical maintenance recommendations from manufacturers. Note that our testing also shows that plate-type EPs generally require more-frequent filter cleaning than filter-based purifiers.

But you’ll likely spend more to maintain and run a filter-type purifier than you will for an electrostatic precipitator since the former type normally uses replacement filters and consumes more electricity.

Still, if you’re unlikely to perform the necessary maintenance, opt for a filter-type purifier, which we consider your best choice overall because it cleans the air without producing ozone. Research is increasingly warning against adding ozone to indoor air, though more studies need to be conducted to determine the effects of low-level ozone exposure on humans.—Ed Perratore

Essential information: Our Ratings of room and whole-house air purifiers include annual costs for energy and filters or other media. Read our advice on how to improve the air quality in your home without an air purifier.

Scam Alert: Avoid “dirty” duct cleaners

The scenario: You get a flyer in the mail from a company offering to clean the air ducts at your home for only $99. Intrigued by the low price, you contact the company and set up an appointment.

When the company arrives at your house, the rep tries to sell you on a bunch of other services, including carpet cleaning or mold remediation, to improve the air quality inside your home. If you don’t bite at these invoice-increasing items, he gives your ducts a cursory cleaning before moving on to the next mark somewhere in your area.

That lowball offer should have been a red flag to avoid that firm. A reputable company will charge $400 to $1,000 to clean the ducts in a typical 2,000-square-foot house, says the National Air Duct Cleaners Association (NADCA). A quality job should take two pros, who’ll use specialized tools, about 4 to 6 hours to complete.

Even more important to know is that there’s no proof that cleaning ducts prevents health problems, according to the U.S. Environmental Protection Agency. Nor do studies conclusively show that dirty ducts increase levels of airborne particulates in a home. Still, there are times when you should get your ducts cleaned:
• Have the ductwork cleaned if it contains visible mold buildup or has debris coming out of supply registers, or if the ducts are infested with vermin. Check for problems by removing the registers and shining a flashlight into the ductwork.
• Consider having your ductwork professionally inspected if someone in your home is suffering from unexplained allergies or illness. Before you do that, however, a doctor should rule out other causes.

To find a reputable duct cleaner, get referrals from the company that services your furnace. You’ll also find NADCA member contractors in your area on the association’s Web site. Before you sign a contract, ask for evidence of contamination, including a lab report if mold is a concern. And be sure the company cleans the entire HVAC system, including the ducts, heat exchanger, and air handler.

After the work has been completed, insist on a thorough visual inspection—all components of the HVAC system should be free of visible dust and debris. A top-shelf pro might even use remote photography to show you the clean ducts.

Essential information: Read “Filtering the Claims” for information on air purifiers.

Tip of the day: How to choose an air purifier

Consumers Union, the nonprofit publisher of Consumer Reports, continues to urge the U.S. Consumer Product Safety Commission to set indoor ozone limits for all air purifiers and mandate performance tests and labels disclosing the results. CU also urges the Federal Trade Commission to investigate air purifier ads to determine the validity of health-related claims.

But if you're set on buying an air purifier, read our latest report “Filtering the claims” and see our Ratings of room and whole-house models (available to subscribers) and keep these points in mind:

Consider a whole-house air purifier. Forced-air heating/cooling systems circulate so much air that they can overwhelm portable purifiers. Whole-house purifiers are a better option. Better products range from $10 to $30 for do-it-yourself filters (shown) to $1,000-plus systems that have to be installed by a pro. The latter are more effective at removing dust and smoke.DIY furnace filters do nearly as good a job of removing dust but aren't as good at removing smoke. Buy a whole-house air purifier with a filter rather than an electrostatic precipitator, which produces some ozone.

Buy a bigger portable model. Portable air purifiers work best at high speeds but are quietest on low. Run the unit on the higher, louder setting when you're not in the room, and turn it down to low when you're nearby. Or buy an air purifier certified for a larger area. We believe a clean-air delivery rate (CADR) above 350 is excellent, and one below 100 is poor. Look for CADR figures with an Association of Home Appliance Manufacturers (AHAM) logo. Only those were confirmed by AHAM.

Avoid ozone generators. Makers of ozone generators often target home users with claims that the devices reduce allergens such as dust, smoke, pollen, germs, and mold.

But our tests found that even at the low everyday settings on some ozone generators, their ozone production quickly exceeded the Food and Drug Administration’s 50 parts per billion limit for medical devices. Purifiers aren't considered medical devices by the FDA.

The U.S. Environmental Protection Agency warns that relatively low levels of ozone can cause chest pain and shortness of breath. Ozone might also worsen asthma and compromise the ability of the body to fight respiratory infections. The EPA regulates outdoor ozone levels, but there is no federal agency that regulates indoor levels or air purifiers. California has recently banned the sale of ozone generators for most uses.—Ed Perratore

Carrier air conditioner, heat pump recall

The U.S. Consumer Product Safety Commission on November 7 announced the recall of about 185,000 Carrier Corp. packaged terminal air conditioners (PTAC) and packaged terminal heat pumps (PTHP) due to a fire hazard.

For detailed information on the recalled air conditioners and heat pumps, go to the manufacturer’s recall page or read the CPSC's announcement.

If you own one of the affected models, do not use the heating mode until it has been inspected as per Carrier's instructions. You can contact Carrier (800-761-8492, 8 a.m. to 6 p.m. ET, Monday through Friday) to receive a free repair.

California regulates “ozone generator” air purifiers

In a step that surpasses federal and other state efforts to regulate the emissions from air purifiers, the California Air Resources Board has moved to ban the sale of some ozone generator air purifiers and could even affect some air purifiers that generate ozone as a by-product.

In late September, CARB deemed “hazardous” hundreds of different models of ozone generator and air purifier that emit ozone in amounts greater than 50 parts per billion (ppb) in tests and approved a regulation to limit the amount of ozone air purifiers can produce to be certified for open sale in the state. Manufacturers will have 24 months from when the ruling takes effect (the projected date is next April) to get their air purifiers tested by a nationally recognized testing laboratory and certified by CARB.

Beyond that 24-month period, any model that that exceeds the 50-ppb threshold must be labeled as appropriate only for industrial use and have a warning about its ozone emissions; electronic models for residential, commercial, in-vehicle, and personal use are affected. CARB also plans to embark on a public-education campaign to discourage state residents from buying ozone generators even before the 24-month period has elapsed.

The California regulation particularly targets what are commonly called ozone generators, which by design produce large amounts of ozone. Manufacturers of ozone generators tout a variety of health benefits. However, the federal EPA has cautioned generally that any ozone produced would have to greatly exceed public-health standards to be effective at removing most indoor-air contaminants and irritants, including germs, smoke, dust, and odors.

(The best-selling air purifiers in the U.S. market are known as electrostatic precipitators. Sold by Oreck, The Sharper Image, and others, they use a technology that typically produces less than 50 ppb of ozone as a by-product; these will also have to undergo testing. Another type, filter-based models, produces no ozone.)

Even relatively low levels of ground-level ozone, the chief ingredient of smog, have been linked to decreases in lung function and increased risks of throat irritation, coughing, chest pain, and lung-tissue inflammation. For outdoor air, the federal standard is a maximum eight-hour average concentration of 80 ppb; California’s standard is 70 ppb, near the level the U.S. EPA has recently proposed.

While no formal standard for indoor air exists, the U.S. Food and Drug Administration imposes a 50-ppb limit on medical devices. But air purifiers don’t fit into this classification.

The regulation, according to CARB, could prevent exposure to potentially harmful levels of ozone for an estimated 828,000 Californians. CARB has generated a list of potentially hazardous ozone generators, which includes products designed for use in single rooms, whole houses, cars, entire floors of commercial spaces, and even “personal air purifiers” worn around the neck. Note that CARB will periodically update the list, and that a product’s nonappearance on the list doesn’t mean it is necessarily safe. No whole-house products that attach to forced-air HVAC systems, for example, are so far on the list.

Eliminating allergens and ventilating spaces are more effective than any air purifier, say experts at the U.S. Environmental Protection Agency and the American Lung Association. If you’re considering buying an air purifier, read our latest report, “Filtering the claims,” from the December 2007 of Consumer Reports .—Ed Perratore