Polluted air
The air is full of particulates that can aggravate asthma and allergy symptoms. While fully eliminating allergens and other air pollutants in a normal environment is not possible, filtering the air is possible through the use of air filters. The two most popular choices are different types of filters: the electronic air filter and the mechanical HEPA filter, both of which offer strengths and limitations.
Electronic Air Filters
There are two types of electronic air filters available. The first is called an electrostatic precipitator, which uses static electricity to collect charged particulates such as dust and animal dander in its collector plates, which need to be cleaned occasionally. The other type is called an ion generator, which charges the air with ions---negatively charged particles---that bind to the positively charged allergens, making them heavier. The particulates will then settle more quickly on surfaces to be cleaned or vacuumed up.
Warning
While there have been positive results in the medical community with ion generators as in the yearlong trial at St. James' Hospital by the University of Leeds as discussed in the "New Scientist," there are no regulations on electronic air filter efficiency. This means that in purchasing an ion generator, there is no way to measure how effective a particular model or brand is.
HEPA Filter
The high efficiency particulate air, or HEPA, filters are used in various machines such as air-conditioning units and vacuum cleaners to filter the air. HEPA filters, as the name indicates, have a high efficiency, according to the American Society of Heating, Refrigerating and Air-Conditioning Engineers measurement of MERV (minimum efficiency reporting value) ratings. Ranging from one to 20, HEPA filters have an efficiency rating of 17 to 20.
Considerations
HEPA filters are very efficient in filtering out larger irritating particulates like pollen, pet dander, dust and even some molds. They are limited, however, as they can only filter the air pushed through the filter. Due to this, only the air of smaller confined spaces can be easily cleaned and maintained. HEPA filters do need to be replaced at regular intervals.
Expert Insight
The Asthma and Allergy Foundation of America recommends the use of both electronic air filters and HEPA filters concurrently for best results. There are even combination devices that use both filters for maximum efficiency and minimized cost.
Tags: HEPA filters, electronic filters, high efficiency