HEPA vacuum cleaners are the only vacuum cleaners that should be sold. The rest recycle dust back into room air, potentially leaving the air dirtier than it was prior to vacuuming.

“HEPA” stands for “high efficiency particulate arrestor,” in other words, a superior filter. You wouldn’t want a vacuum cleaner with an ineffective filter, because then dust and other allergens would be recycled right back into room air. With a HEPA filter, 99.97% of the particulates 0.3 microns (size of mold spores) or larger are captured by the filter (“arrested” by the filter).

There’s no watchdog around checking the quality of filters. Some companies make claims for HEPA filtration, but the evidence doesn’t necessarily support their claims.

I use a MetOne laser particle counter to measure the numbers of particulates in the exhaust air coming off the filter. With a quality HEPA vacuum cleaner, my particle counter reads close to zero at the filter.

There’s a second issue, however, when looking at HEPA vacuum cleaners. What if the chassis of the vacuum cleaner is leaky? What if air escapes back into room air without first going through the HEPA filter? You have to find a HEPA vacuum cleaner with a sealed chassis. Canister vacuums generally deliver better on this requirement than uprights, though there are a few uprights with sealed units.

Question: My house has a whole house vacuum system. Is that ok?

Response: A whole house vacuum system is fine, as long as it has adequate suction. With a whole house system, there is an “outlet” in each room where a hose gets attached. The discharge canister should be placed in a garage, not in the basement, because particulates are released from the canister.

Some suggestions for residential canister HEPA vacuum cleaners:

• Miele, Calima model or equivalent – about $500-$800 – designed for residential use, retractable cord, canister design. Some Miele vacuums are not HEPA units, so look for the “HEPA” designation. Make sure the filter is a HEPA filter.
• Nilfisk GM 80, with ULPA filter – about $1100 plus $250 for the ULPA filter – This is a top of the line HEPA vacuum cleaner, a lifetime unit. Compare the features with Mieles, though. The Nilfisk, for example, does not have a retractable cord. ULPA gives even finer filtration than HEPA. This is an industrial model that can be used for mold cleanup and for regular vacuuming. Go on-line for prices.Note: Nilfisk (aka EuroClean) offers other, less costly, models, such as the GD 930 and the UZ 934. The placement of the filter is before the motor, which means that the laser particle counter has a high reading in exhaust air because of the motor stirring up dust. I’d rather see the filter after the motor.

  Question: What about power nozzles? Don’t they stir up dust, too?

  Response: Yes, they do. Stick with a non-electrified nozzle, such as a rotary or turbo model.

  Tip: Nilfisk stopped selling the Family Vac model, which is what I have. You might keep an eye on eBay to monitor when a used one becomes available. A client got a dandy for $250. There are a lot of Family Vacs out there, so repair services should be supported for a good time to come.

  As I write, there is a Nilfisk GS 80 Clean Room Vac on eBay, listed for $325. I don’t know this model but it’s probably fine, and a good price, even if a repair is needed. If I needed a vacuum cleaner, I’d place a bid, assuming the description was acceptable.

• Other manufacturers offer lower cost HEPA models, usually canister models, such as the Electrolux Oxygen (Costco, $250). If buying one of them, before using it on the floor, turn it on, wet your hand, and run your hand over the chassis to see if you can pick up on any air leaks. If you do, consider returning the vacuum cleaner before using it.

There are a few choices if you prefer upright HEPA vacuum cleaners, such as:

• The Dyson and Dyson-like vacuums generally have sealed canisters. However, they are bagless, which is not recommended, because you could be exposed to dust when emptying the collection container.
• Check out the Nilfisk Spectrum. I have not seen this unit in person and cannot confirm how it would perform when checked with a laser particle counter.
• Shark offers a model with a sealed chassis – Shark Lift Around Complete Seal canister – for bare floors, $79.99, seen at Costco. Empty the collection cup outdoors.

General points when considering HEPA vacuum cleaners:

• Canisters are preferred over uprights. Vacuum cleaners with bags are preferred to bagless. Some HEPA uprights are heavy.
• Eureka makes a green HEPA canister vacuum, which I have not seen to measure. With recycled plastics, the odor is usually minimal. This machine, along with Miele models, can be viewed at www.allergybuyersclub.com.
• If considering a water-based vacuum cleaner, it must have a HEPA filter or the tiniest particulates will shoot out in exhaust air. The surface tension of water is too great for the tiniest particulates to be absorbed.

Question: What about room air purifiers? Should they have HEPA filters, too?

Response: Yes, if your main concern is particles. If your main concern is odors, then get a carbon-based filter, such as the Austin Air. Do not put an Austin Air in a damp basement, because mold and bacteria can grow in carbon.

Remember (if you’ve read the EMF section) that motors give off AC magnetic fields. If you must have a room air purifier in the bedroom, plug it in away from the bed, and, if possible, turn it off at night.