Carpet Cleaning and IAQ
May 14, 2007
It started, as it so often does, with a phone call, Mrs. Piffleton calling to schedule the annual spring-cleaning of the carpets. She informed me, almost smugly, that there would be no need to clean the upstairs bedrooms and hall.
Those previously carpeted areas were now covered by bright new laminate flooring at the behest of her son’s allergist, who is convinced that carpets are a prime contributor to the asthma and allergy woes of said son. That seems to be a popular view of many allergists today, even though scientific reviews and anecdotal evidence would seem to indicate otherwise.
The first major indications that carpet may not be a “bad actor” came from Sweden where use of “fitted” carpets was discouraged starting in the ‘70s due to concerns about asthma and allergies from the carpets. Carpet had a market share of 40 percent in the ‘70s; it would sink to 2 percent of market by 1992. This precipitous decline in carpet usage was accompanied by an equally precipitous increase in asthma and allergy-related problems.
Also from Sweden came a 1995 research study of “sick building syndrome” in 55 buildings housing different businesses, each employing at least 10 people. Only two of these “sick” buildings had carpets. These are anecdotal reports; however, the implications of carpet’s rather benign qualities are quite strong.
The first discussion of the physical properties of carpet relative to indoor air quality probably came from Dr. Michael Berry in his groundbreaking 1993 book, Protecting the Built Environment: Cleaning for Health, when he described carpet as a “sink” which would positively impact IAQ by acting as a filter and trapping airborne particulates (presuming the carpet is properly maintained and cleaned on a regular basis). At the same time he warned that heavily soiled carpet could become a source for air contamination due to trapped particulates at levels higher than the carpet’s ability to adsorb soils.
In a letter dated Jan. 31, 1989, Dr. Berry makes the following statements regarding soils and their extraction from carpets:
“When vacuuming carpets the greatest health benefit is derived by extracting fine respirable particles, particles which are bound to pollutants, biological allergens, heavy metals such as lead, cadmium, arsenic found in outside soil dusts, pesticides and herbicides, combustion products from cooking, wood smoke, candles, and tobacco to name a few. Furthermore, the benefit of extracting is the overall reduction of respirable particles which cause most health effects, reduced cases of biologically induced illnesses, reduced lifetime cancer risks, and reduced complaints for building owners and managers.”
In addition, the position of Mrs. Piffleton’s son’s allergist relative to carpet would appear to be undermined by the results of a research project conducted at Cornell University. Alan Hedge, professor of design and environmental analysis at Cornell, observes that, “concerns that carpeting in schools is contributing to an increase in respiratory problems, allergies and asthma in schools are unfounded.” and “as long as schools keep floors clean and use high-efficiency microfiltration vacuum bags or HEPA filtration, carpets can be a healthy, safe, and economical floor covering in schools and day-care centers.”
Carpeting can improve IAQ, Hedge says, because it captures and holds dirt, contaminants and allergens that would otherwise become airborne. Theses substances are readily and effectively removed by vacuuming using high-efficiency bags. Synthetic carpets are better than wool, Hedge says, because their fibers’ electrical charge attract potential contaminants. Synthetic carpets are easy and economical to clean in the long run and, like any other floor surface, provided they are kept dry and clean, they will not promote microbial growth.
It would seem, from these statements of varying members of the scientific world, that carpets might actually be much healthier from a contamination standpoint than a smooth floor covering. Hmm.
And there’s more. Tests conducted at Professional Testing Labs in Dalton, Ga., utilizing walking tests on carpeted floors and smooth floors, resulted in airborne particle levels some nine times higher on smooth floors compared to carpeted floors. From these tests, one may conclude that carpet holds particulates nine times better than a smooth floor, and carpets would therefore allow much less contaminants to become airborne during normal walking in a room.
Mrs. P may find her son’s doctor bills and asthma symptoms to be much worse after the carpet is removed. Well, there is still carpet downstairs for me, so I guess I won’t sell my carpet-cleaning equipment quite yet. But perhaps I should spend some time learning about hard-floor maintenance. It may behoove us all to be prepared to service hard floors. And be thankful that much of the carpet-cleaning stuff can be used on the hard floors.
Until next time, see ya!