According to Dr. Michael Berry in his book, "Protecting the Built Environment: Cleaning for Health," each day an adult consumes "about two pounds of solid food, four pounds of liquids and 30 pounds of air." He notes that, "by far the dominant path for [harmful indoor environmental] exposure is breathing or inhalation." The quality of air inside buildings affects human health perhaps more than any other single factor.
Tiny particulate matter floating in the air is composed mostly of pollen, dust mite fragments and feces, mold and mildew spores, bacteria, and miscellaneous types of dust laden with other contaminants. Breathing this may cause headache, fatigue, shortness of breath, sinus congestion, cough, sneezing, irritation of the eyes, nose, throat or skin, dizziness and nausea. In some people, it can trigger severe allergic reactions and asthma.
Many contaminants in the air eventually come to rest on floors and other surfaces. Improperly cleaned carpets can become "dust sinks" that hold more than their weight in dirt and contaminants. When the "sink" becomes full, it begins releasing contaminants into the indoor environment.
Poor quality vacuum cleaners and inadequate vacuuming frequency are the leading factors contributing to excess soil in carpet. In turn, vacuum cleaners with poor filtration take the fine dust trapped in carpet and blow it into the air.
Recent Studies Clear the Air
An interesting study was recently conducted by the Carpet and Rug Institute comparing the indoor air quality effect of vacuuming carpet using an efficient vacuum cleaner with dust mopping a hard floor. The study concluded that dust mopping a hard floor released much more contaminant into the air than vacuuming a carpet using a vacuum with effective filtration. Other studies - including those conducted by Colorado State University, Ft. Collins, Colo., and by Service Resources in Bloomington, Ill. - have demonstrated that vacuuming hard floors with a quality vacuum cleaner instead of dust mopping removes more soil, reduces airborne contamination, and reduces the labor and frequency of hard floor care.
Developments in Vacuum Technology
As far back as the 1980s, it was clearly recognized that vacuuming was an essential component of IAQ. Studies were undertaken to test the effectiveness of vacuum cleaners and filtration material. Cloth filter bags, as primary filters, removed only 30 percent of the particulates one micron in size (most airborne dust is ten microns in size or smaller). Many of the contaminants passed through the filters and were pumped back into the air. Sometimes the allergens in the room would increase ten-fold1
According to Dr. Berry, "the pulmonary system's natural defense mechanisms usually clear the lungs of particles greater than 10 microns...[however] very small particles - especially those smaller than 10 microns - can get deeper into the lungs and do the greatest harm."
Since the 1980s, with high-profile 'sick' building problems emerging, the prevalence of 'airtight' buildings for energy conservation, the increase in asthma cases, and the EPA's push to prevent asbestos exposure, the filter industry has improved air filtration in both building heating and air conditioning systems as well as filtration in commercial vacuums. Both the filter and vacuum industry have come through with dramatic improvements.
Micro Filters. A high-quality disposable micro filter bag captures fine dust and allergens while enabling air to move easily through it. The more square inches of filtration area the bag has, the longer and more efficient it will be at both these tasks. Filtration efficiency for a quality micro filter in a four-stage configuration is 99.77 percent at 1 micron. Because the construction and quality of disposable filter bags varies greatly, it is important to stick to genuine OEM filters versus cheap generic replacements, or at least to compare lab test results for filtration efficiency and airflow between OEM filters and after-market varieties.
HEPA Filters. Today's true industrial HEPA (high efficiency particulate air) filters are 99.97 percent effective at containing particulate matter 0.3 microns and larger. Of course, these efficiency ratings are meaningless unless the vacuum itself is sealed and not leaking particles through body seams and other locations. HEPA filters must also be proportioned to the airflow of the vacuum to be effective. Lastly, the filters preceding the HEPA filter should be very efficient to trap most of the fine dust and prevent loading the HEPA filter, reduced airflow and suction, motor overheating and premature (and expensive) HEPA-filter replacement.
HEPA-like or HEPA-type Filters. These more affordable alternatives may remove 99.79 percent of particles 0.3 microns and larger. In some backpack vacuums, this filter takes the form of a high-filtration disc that retails for less than $10 and provides a cost-effective alternative to much more expensive HEPA filters.
Electrostatic Filters. As air passes through this type of filter, an electrostatic charge causes fine dust to cling to the filter media. Efficiency ratings depend on the actual filter media and configuration.
Multi-stage Filtration. A series of filters in succession may include a micro filter, a cloth bag, a motor intake filter, and a final exhaust filter. A typical configuration of this type will yield a 99.77-percent efficiency at 1 micron or better depending on the filter media and layout.
Sealed Construction. For the filtration of any vacuum to be effective, the vacuum construction must be completely sealed. Dust leakage through seams in vacuum bodies largely negates the inherent efficiency of the filters.
Direct Suction Vacuuming. Vacuums with beater bars or agitation may kick fine particulate into the air if the airflow is inadequate or reduced through poor maintenance or design issues. Considerable suction is lost through the large orifice necessary to accommodate the beater brush in those vacuums. Strong, point-of-contact suction concentrated at a smaller tool opening as found in suction-only backpack and canister models results in much more efficient soil removal and fine particulate capture on commercial looped pile carpets.
Improved Motor Technology. It's important to choose a vacuum with high CFM (cubic feet per minute of airflow) and static lift. The best filters in the world are useless if dust and debris are never pulled into the vacuum. Since manufacturers cite these ratings based on ideal conditions measured at the motor, consider the construction of the vacuum (e.g., completely sealed or not) and the size of the tool orifice, along with the rating.
IAQ - Get Informed and Breathe Easy
If you've been waiting for the discussions and emphasis on indoor air quality to fade away, you're going to be disappointed. The Carpet and Rug Institute is doing its part to help promote better IAQ. In its Green Label testing program, vacuum cleaners are tested for soil removal, filtration efficiency and carpet appearance retention. The dust containment protocol requires that "a vacuum cleaner will release into the environment no more than 100 micrograms of dust particles per cubic meter of air, well below levels stated in the National Ambient Air Quality Standards." Vacuum cleaners that meet these criteria bear CRI's Green Label.
With the right vacuums and practices, cleaning professionals can do so much to improve indoor air quality with little additional effort and expense. There's no way around it: ignoring IAQ is just a bad business decision. Paying attention to it by selecting the right vacuum cleaner will pay big dividends and help you and your customers breathe easier.