The truth about vacuums

Buying a device to suck up dust and dirt has never been so complicated. You can choose one that promises extra suction or allergen filtering. You can even opt for a robotic vacuum that does the work for you. But good luck finding a machine that really gets your floors and carpets clean and keeps the dirt in the vacuum where it belongs. These guidelines will tell you more.

No. Vacuums with allergy filters aren't perfect — and many vacuums spew almost as much dust and dirt as they suck up. If you're allergic to dust mites, pollen or pet dander, you've no doubt heard the advertising claims about the wonders of vacuum cleaners equipped with high-tech HEPA (high-efficiency particulate air) filters. These systems are sometimes touted to remove 100 percent of the microscopic nasties that provoke coughing, sneezing, watering eyes and even full-fledged asthma attacks. But scientific research suggests otherwise.

When British researchers wearing particle-trapping devices in their nostrils tested old vacuum cleaners and new HEPA-equipped models in homes, they found that all types sent clouds of cat dander and dust mites flying into the air — and into their respiratory systems. Even more particles wafted into their noses when they changed the filter bags or emptied the machines.

Floor coverings like wall-to-wall carpet and area rugs are the single largest "reservoirs" of sneeze-producing particles in your home. Studies conflict about whether vacuuming really removes any of these allergens at all. In one, researchers found that vacuuming redistributed dust and dander built up in older rugs. Another found that vacuuming released a whopping 90 percent of small-diameter cat dander particles into the air. But one, conducted in 60 homes over the course of a year, found that regular vacuuming — with a standard machine or a HEPA model — cut levels of cat dander by about 50 percent in carpets and upholstered sofas. Levels fell by 80 percent in mattresses. Dog dander levels fell, too — and standard machines often did a better job. The downside? While vacuuming may have helped with pet dander, it increased levels of dust mites.

No. Real-world tests show that lower-priced machines often work better. Despite manufacturer's claims, several head-to-head tests of vacuum cleaners have found that expensive, bag-free machines purported to "never lose suction" were outperformed by less expensive models. While these vacs cleaned carpeting well, they left dust and dirt on bare floors and were unexceptional when it came to sucking up pet hair. One model didn't lose suction, but reviewers noted that it had less dirt-removal power to begin with. Another reviewer said that his machine leaked clouds of dust when he tried to empty it.

Your best bet: consult an up-to-date consumer review for the latest ratings before you buy.

These guidelines will help you separate fact from fiction when buying a vacuum.