There is little argument that the true HEPA air purifier has the ability to remove more particulates from the air than any other type of filtration system.
A true HEPA air purifier removes 99.97% of the dust, dander and pollens present in the air in a typical home environment.
The term HEPA stands for “high efficiency particulate arrestor”. It is not a brand of air cleaner but a type of air filter use in many of the best air cleaning systems.
HEPA filters are usually made of fiberglass fibers at diameters between .5 and 2.0 micrometers. The fibers form a mat that acts as the filter ad the efficiency of that filter depends on several factors.
Air space is trapped between the layers of fibers that form the filter itself. True HEPA purifiers use filter that target very small particles present in the air. The particles are trapped when they stick to one of the fiber layers of the filter.
The methods by which particles of various sizes and types are trapped by a true HEPA filter are referred to as interception, impaction and diffusion. The retention of particles through those three processes is the basis of specifications developed to rate HEPA filters.
HEPA filters are defined by a Department of Energy standard that is used by most industries in the U.S. The standard to be labeled a true HEPA filter is the removal of 99.97% of airborne particles from the air for particles as small as 0.3 microns in size. In addition there are airflow resistance ratings that measure how well the filter allows air to be blow through it.
Origin of The HEPA Filter
In the 1940s, the HEPA filter was developed for use in the Manhattan Project. The goal was to prevent airborne radioactive contamination from spreading during the construction of the atomic bomb.
The term HEPA became a registered trademark in the 1950’s when the product was introduced to the commercial market. That name has developed a generic meaning used to describe high efficiency filters.
The filters have been improved and expanded on in years since as the demand for safe air and improved air purification methods has grown in industry. Pharmaceuticals, hospitals, aerospace, nuclear power and electronic circuitry such as computer chips require clean air for their manufacturing systems.
The best HEPA air purifiers are in use in hospitals across the country. These specialized filters have a high efficiency rating of 99.995% to limit the spread of airborne diseases.
On the home front, HEPA filters first appeared as vacuum cleaner filtration systems. This added the capacity for removing dust from the air when using a home vacuum cleaner and eliminated small particles of dust being released back into a room through the vacuum’s exhaust port.
Many vacuums today advertise they use a HEPA filter but unless the machine is designed so all the air drawn into the machine is all expelled through the HEPA filter, they are not very efficient.
True HEPA air purifiers carry a MERV (Minimum Efficiency Reporting Value) rating. This rates the capability to filter dust particles as the air passes into and through the filter. Higher MERV ratings indicate true HEPA air purifiers that remove more (and smaller) particles on a scale that ranges from 1 to 20.
Airlines use the true HEPA air purifier system to reduce the spread of particulates and dander in the recirculated air of the closed cabins during flights. Airlines used true HEPA air purifier filters similar to high efficiency filters used for hospital clean rooms.
The best home air cleandfs on the market today are produced as a true HEPA air purifier. The only downside for home use is the need to change the HEPA filter on occasion.
A true HEPA air cleaner can clean the air in one space or room. A good quality unit used in a room will cycle the air in the room up to 15 times per hour in an average sized bedroom. In a larger room the unit may cycle up to 8 times per hour. This type of air cleaner will not be effective in cleaning an entire house or cleaning the air in adjacent rooms if placed in a central hallway.
Lower cost units are not as efficient as the higher priced models offered by companies who have long specialized in air purification systems. Low priced units found in many department stores and online are likely to cycle the air in an average bedroom only 2-4 times per hour. Used in a large room, the exchange rate of the air will not be high enough to make a difference in the air quality indoors.
Higher end products also may often include additional filters that help extend the life of a replaceable filter or add additional clean air benefits. Ultraviolet lamps or light systems may be added to kill bacteria, viruses and mold spores.
There may be one or two pre-filters in the unit that capture larger particles of dust and dander and extend the life of the true HEPA filter. The pre-filters may be washable and rarely require replacement.
Another addition on many units is an activated carbon filter. This has been long known as a way to remove odors from the air and a good choice for homes where smoking, cooking or pet odors leave the air smelling stale.
One addition that many consumers appreciate is an ionizer that is activated at the end of the cleaning cycle. Air may enter pre-filters, then pass through the true HEPA filter and then be exposed to an ion generator which produced negative ions in the air as the air is returned by a fan into the room. Ionization provides a clean smell to the room’s air and adds an outdoor effect of fresh air to the room.
If you are looking for an air purifier that will truly clean dirt and pollens, dander and dust from the air in you room, a true HEPA air purifier is an excellent choice. The price depends on the quality of the unit, the strength of the fans and the type of filtrations system used.
You will need to change the true HEPA filters on occasion but most filters require only a new filter only once a year. If you carefully read the instructions for maintenance you will find a unit that is easy to care for and will provide clean, healthy air in your home.