Types of Air Purifiers
Improve Air QualityHEPA Vacuum Cleaners
One of the most primary intervention techniques that has been shown to be effective in reducing respiratory ailments due to allergies or asthma has been keeping the environment as free of particles such as dust, pet dander, and other airborne allergens. Dust has been shown to be a significant trigger substance for allergic and asthmatic attacks. Vacuum cleaning is one of the first-line measures that must be undertaken when there is the need for substantially improving the indoor environment and reducing allergen exposure. Vacuum cleaners outfitted with HEPA filters are particularly effective in combating dust. Vacuuming alone can reduce much of the household dust and overall amount of exposure.
A major contributor to indoor air contaminants is the carpet. Carpets and carpeting embed large amounts of particulates. The HEPA vacuum filter has been shown to be quite effective in removing annoying particulates, especially pet dander and many sufferers and their families who have pets cannot bear to part with them.*
Vacuum cleaners fitted with high-efficiency exhaust filtration can be recommended for lowering home allergen exposure levels. HEPA filters, along with PE (washable polyethylene) filters can control the airborne dispersion of indoor allergens. (Allergy Net from Allergy 2002; 55:555) PE filters can be washed and do not need to be replaced as often as HEPA filters.
Selecting a high quality HEPA vacuum cleaner
In order for a filter to be certified as a HEPA filter, it must be able to filter particles down to .3 microns with a 99.97 efficiency in removal. The information on the filtering capability for the HEPA filter should be clearly marked. A true HEPA has to be individually tested and certified. This information is printed on the filter. HEPA-type filters are usually not subjected to this rigorous testing standard and rather than operating at the 99.97 percent efficiency level, perform at 85-95 percent efficiency. A considerable difference.
For the vacuum cleaner itself, the following are some basic considerations. Ball bearing wheels and casters are recommended which are large enough for the vacuum cleaner to move without problem over uneven floors and even up and down stairs. How easy is it to clean and dispose of the collected refuse is another key consideration. Also, are there stainless steel or aluminum surfaces which allow for ease of cleaning. Check the motor. The higher quality vacuum cleaners have a two-stage or bypass motor as opposed to the less expensive single-stage motor. Then there is the filter system. A good HEPA vacuum cleaner has three or even four prefilter in addition to the HEPA filter. These filters then remove the larger particulates allowing the HEPA filter to concentrate only on the smallest particles. These additional filters also mean that the HEPA filter can be more effectively utilized and there is then a cost savings because the prefilters are doing the heavy lifting so to speak first which means a longer life for the HEPA filter.
However, the next consideration that is quite important is the positioning of the HEPA filter itself in the vacuum cleaner. There are a number of options that a manufacturer can chose and, unfortunately, the conclusive answer as to which location is best is still inconclusive. There are reasons for preferring the filter to be placed on the intake side of the motors rather than on the exhaust side.
Performance Ratings
There are two key performance ratings: air displacement and static lift. Horsepower alone or the wattage is not the most critical factor in the power of the vacuum cleaner. The number of motors and their respective speeds are critical factors. You want a vacuum cleaner that can displace large amounts of air (CFM: cubic feet per minute) which is the best for removing dust, fibers, even bacteria, etc. That is, for the type of contaminants that one wants to remove in the household, higher displacement is more important than static lift. The HEPA filter should be certified for the air displacement of the vacuum cleaner and this should be checked.
It is also useful to find a model that has a device installed that lets the operator know when it time to change the filter. There are a number of different devices and ways to do this, but it is a very useful feature. If you change the filter too soon, that is than an extra cost and if you wait too long, the filter is no longer operating at its peak efficiency.
One of the nice things about the HEPA filter is that it actually gets better with use simply because as it traps particles, this reduces the size of the glass fiber filter.
See the study by H. Francis, “Clinical effects of air filters in homes of asthmatic adults sensitized and exposed to pet allergens.” Clinical and Experimental Allergy 2003:33:101-105.
