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 it will last and more efficient it will be. Consisting of two or more plies, a micro filter captures more fine dust than single-ply paper filters, and is also more expensive to buy. Because the construction and quality of disposable filter bags varies greatly, it may be helpful to stick to genuine OEM filters (those sold by the company that made your vacuum) versus generic replacements, or at least to compare test results for filtration efficiency and airflow between OEM filters and after-market varieties (manufacturers may provide this on request). A bargain isn’t always a bargain.

 

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HEPA filters. Today’s true HEPA (high efficiency particulate air) filters are 99.97 percent effective at containing particulate matter 0.3 micron and larger in size. 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 or clogging the HEPA filter, reduced airflow and suction, motor overheating and premature (and expensive) HEPA filter replacement.

 

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 95 percent efficiency at 1 micron or better depending on the filter media and layout.

Bagless vacuums. Cyclonic vacuums spin airborne dust causing particles to drop out of the airflow into a dust container without the use of filter bags. Cyclonic filtration still requires the use and maintenance of a final physical filter that catches what passes through the dirt bin.

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.