A high efficiency particulate air (HEPA) filter vacuum contains a filtration system that consistently removes the smallest of airborne particulates without creating any kind of byproduct from the process. There are three types of filtration vacuums on the market: true or sealed HEPA vacuum cleaners, non-sealed HEPA vacuum cleaners, and HEPA-like vacuum cleaners. A certified, true, or sealed HEPA vacuum cleaner has a closed filtration system and is often recommended for those with respiratory conditions. Models marketed as HEPA vacuum cleaners, but whose filtration system is open, do have an authentic HEPA filter although captured particles may escape. The vacuums labeled as HEPA-like may have a filter similar to a HEPA, but is one that does not meet the requirements for certification as a true HEPA vacuum cleaner.
All true HEPA vacuum cleaners must trap 99.7% to 99.9% of air particulates as small as 0.3 microns in size; HEPA certification will be stated on the vacuum's label. In Europe, the HEPA-certified vacuum cleaner is referred to as a grade 13 or 14 HEPA. A certified, sealed HEPA vacuum cleaner is designed so that all of the air entering the vacuum must pass through the filtration system before exiting the machine. All of the air particles captured by this type of vacuum cleaner remain inside the vacuum until the filter is cleaned or emptied. This is why doctors often recommend sealed HEPA vacuum cleaners to patients with asthma, allergies, and other respiratory health conditions.
Sealed HEPA vacuum cleaners may use a single filter or multiple filters. To keep the vacuum functioning properly, the filter should be removed at least once a year. Some filters can be washed and others are disposable. The reusable filters are more expensive initially, but may save the purchaser money over the long term.
Some vacuums use real, certified HEPA filters, but lack a sealed filtration system. This means that the vacuum may pick up 99.7% to 99.9% of air particles as small as 0.3 microns but some of these particles may end up back in the environment. This is due to the fact that all of the air is not forced to pass through the filter prior to exiting the vacuum. The system is leaky, and air can escape from any cracks once it enters the vacuum.
There are also HEPA-like vacuums with labels claiming to capture 85% or 90% of air particulates as small as 0.1 micron. These vacuums may look quite similar to a genuine certified HEPA vacuum cleaner, but the filters in these machines have not passed the same rigorous testing. The 0.1 micron particle size that these HEPA-like vacuums pick up is not as small as what the certified, sealed HEPA vacuum cleaner can remove. This means that the consumer may be unable to remove dust mites and pollen from the household, thereby making this machine perhaps not be the best choice for someone with allergies or other, similar conditions.