Dear Jim: My children’s allergies seem worse after I vacuum and I can even smell the dust. What should I look for in a powerful microfiltration vacuum cleaner and will running one use a huge amount of electricity? – Linda S.

Dear Linda: Using a powerful, microfiltration vacuum cleaner certainly cannot hurt when it comes to controlling allergens in your home. I have allergies to pollen, dust mites and cat dander. After testing many of these new models in my own home, I seem to have fewer allergic problems.

These microfiltration vacuum cleaners do have extra powerful motors that consume a lot of electricity. Since they deep clean so thoroughly and are so well sealed, you need to vacuum less often than with a standard model. Overall, the electricity usage from using one is not any greater.

To be effective, a vacuum cleaner must not only have a very powerful motor to suck up dirt and allergens, but it must also contain the fine particles inside of it until it is emptied. If you get that “just vacuumed” smell, your vacuum cleaner does not filter well or is not well sealed.

The cleaning power of a vacuum is determined by suction (inches of water lift) and air flow. Air flow (cubic feet per minute – cfm), is probably most important. Canister models typically have the highest air flows. Air watts is a combined rating calculated from the suction and air flow.

The two main types of filtration systems are bag or cyclonic. Some high-filtration bags have 28 layers to trap the allergens. Cyclonic (bagless) systems create a high-speed circular air flow inside the vacuum cleaner that forces the particles to drop out of the air before the final filter.

There are three types of HEPA (high efficiency particulate air) models. “True” HEPA means that the entire system meets HEPA specifications. HEPA often means that the unit just includes a secondary HEPA filter. HEPA-like means that the filter is effective, but it has not been tested to HEPA specs.

If the HEPA filter is located after the motor, it also removes fine motor brush dust. An optional final charcoal filter will remove some odors from the air too.

Check the quality of internal seals and how solid the mating pieces feel when the unit is closed. This is most critical on designs with a HEPA filter after the suction motor because it creates a positive pressure. One of the newest features is an infrared sensor that determines when the carpet or item is clean and you can move on. Telescopic or ergonomic curved wands are convenient and more comfortable to use. Adjustable vacuum power levels, with LED readouts and wand controls, offer more versatile cleaning.

Write for (instantly download – www.dulley.com) Update Bulletin No. 968 – buyer’s guide of 10 manufacturers (25 models) of HEPA vacuum cleaners listing cleaning power, filtration methods, HEPA location, bag size, features, weights and prices. Include $3 and a business-size SASE. Send to James Dulley, 6906 Royalgreen Drive, Cincinnati, OH 45244.