Vacuum Cleaners: Not Ghosts, Maybe Gremlins!

The sponge filter on the back of this vacuum had a black circle on it that matched the diameter of the exhaust porthole.

In the early fall of 1999, a builder called in my company to conduct an investigation on a home in Phoenix, Arizona, that had the classic "ghosting" marks: staining around drapes, around bed skirts, at door undercuts, and around supply registers. The only feature of these stains that was nonclassic was their color: They were gray, not black.

Our initial investigation found little evidence that combustion sources were responsible for the stains, because the home had no gas appliances or fireplaces, and the residents didn't burn candles or smoke cigarettes. After consulting with Frank Vigil and other experts at Advanced Energy in Raleigh, North Carolina, we began to suspect that a vacuum cleaner might be the source. Dust from vacuum cleaners typically resembles talcum powder mixed with graphite fines, which results in gray stains. Soot from combustion sources, however, is greasy to the touch and leaves distinctly black stains.

Wanting to keep their house very neat, the homeowners had it cleaned once a week, with heavy vacuuming every other week. The homeowners also vacuumed periodically throughout the week. A previous lab analysis of samples collected at the home by Enviro-Health, an environmental specialist, found abundant powdered talc-like dust at various locations in the home, including at the supply ducts and on the master bedroom TV screen. We found the same thing during our investigation.

The homeowner owned three vacuum cleaners: one fairly new Hoover Convertible High Filtration upright vacuum, and two older Hoover Portapower Model S1049 compact canister vacuums. We observed that the disposable dust bag in the upright was full, but not extremely full. The dust bag was made of a relatively solid, nonporous material.

The sponge filter on the back of the first compact vacuum had a black circle on it that matched the diameter of the exhaust porthole. When the full dust bag was removed, we observed a grainy, black dust line on the top of the bag. This line aligned precisely with the seam in the plastic molding of the vacuum's exterior shell. The dust bag appeared to be made of a fairly porous fabric material. The same markings were present, although less distinct, on the rear sponge filter and dust bag of the second compact vacuum. When asked when the dust bags were last emptied, the homeowner did not know. This homeowner simply shook out the dust bags when they got full--a practice that goes against manufacturer's recommendations always to replace, not reuse, a full bag.

According to Frank Vigil, vacuums often leak more dust back into the house than they remove. An article in Consumer Reports evaluating vacuum cleaners describes several ways in which vacuuming can launch particles into the air, including through porous cleaner bags or out exhaust vents. We found no review of the Hoover Convertible High Filtration upright vacuum in this or any other Consumer Reports article. However, the compact model was evaluated in 1996 and 1999. On a scale of 1 to 5 with 5 being Excellent and 1 being Poor, the Hoover Portapower compact vacuum cleaner rated a 2 (or Fair) in the particulate emissions category in both years.

Based on the evidence that combustion sources were not responsible for the stains, that vacuum cleaners were used frequently in this home, that the vacuum bags were not replaced and filters were not regularly cleaned as the manufacturer recommends, and finally that the vacuum cleaners being used rated only Fair on particulate emissions, only one conclusion could be reached: The source of the stains--or the "gremlins" in this investigation--were none other than the vacuum cleaners themselves.

We made many recommendations in our report to the builder on how to avoid the stains. Our principle recommendation was to get rid of the compact vacuums. High-filtration vacuums, such as the newer upright unit, tend to reduce the production of vacuum dust stains, because these unit retain dust better. The other crucial factor in "ghosting" is the driving force that distributes the dust. The principal driving force in this house was the imbalance between rooms created by the air conditioning system when the bedroom doors were closed. We recommended air balancing to alleviate this problem.

--Daran R. Wastchak

Daran R. Wastchak is a principal owner of Daran R. Wastchak, L.L.C. Web site: www.drwastchak.com.

For more information: Murray, A.B., et al. "Diagnosis of House Dust Mite Allergy in Asthmatic Children: What Constitutes a Positive History?" Journal of Allergy and Clinical Immunology 71 no. 1 (1983): 21-28. "Vac Attack: CR Dishes the Dirt on Vacuum Cleaners." Consumer Reports July 1999, pp. 42-47. Vigil, F. "Black Stains in Houses: Soot, Dust, or Ghosts?" Home Energy Jan/Feb 1998, pp. 15-21.

Home Energy can be reached at: contact@homeenergy.org
Home Energy magazine -- Please read our Copyright Notice