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Welcome to the third issue of the National Allergy E-Mail Newsletter! In February 2003, we began sending this monthly newsletter packed with informative articles, valuable coupons, and exclusive offers to our valued customers and others who have expressed interest. To top it off, every month we're giving away an Austin Air HM-400 Air Purifier, valued at $400, to one lucky subscriber!
After looking at dust mite allergies and pollen allergies, we've gotten a lot of questions about different types of air cleaners. So we've postponed our look at pet dander allergies until next month so that this month we can look at Air Cleaning Technologies and Choosing the Right Air Cleaner For You. If you happened to miss the last two month's newsletters on dust mite and pollen allergies, you can find archived issues of all of our past newsletters on our website. In the coming months we'll have more educational articles about the aggravating factors behind allergy, asthma, and sinus problems and helpful things you can do to find relief.Sincerely,
The National Allergy Newsletter Team
Air Cleaning Technologies and Choosing the Right Air Cleaner For You
An Overview of Air Cleaning TechnologiesHEPA filters were originally developed during World War II to prevent discharge of radioactive particles from nuclear reactor facility exhausts. They have since become a vital technology in industrial, medical, and military clean rooms and have grown in popularity for use in portable residential air cleaners. A true HEPA filter is defined as having a minimum particle removal efficiency of 99.97% for all particles of 0.3 micron diameter. The HEPA rating is determined using a test with particles of 0.3 micron average diameter. To qualify as a "true" HEPA, the filter must allow no more than 3 particles out of 10,000 to penetrate the filtration media. Warning: Filters using less efficient filtering materials are frequently being referred to as "HEPA-type" filters, though their actual efficiency may be 55% or less at 0.3 microns.
In case you're wondering how small a micron is, it is one-millionth of a meter and there are 25,400 microns in a single inch.
Negative ion generators force high-voltage electricity to one or more needlepoints. Electricity is simply electrons in motion. Since electrons repel one another, when they reach the needlepoint, they jump off and attach themselves to the molecules in the air, forming negative ions. At that point the allergens and other particles are attracted to grounded surfaces where they can get rid of that extra electron, causing them to settle on walls, floors, furniture and even on your bed. It's important to remember that a simple negative ion generator doesn't capture or collect the allergens in the air, it simply causes them to precipitate out of the air.
Traditional furnace filters do very little to remove allergens and other dangerous particles from the air. They have an efficiency rating of only 2% for particles between 0.3 and 1 microns in diameter. Those are the most dangerous particles because they get the deepest into your lungs and cause the most damage. Furnace filters have to balance filtration with airflow through your ventilation system. If a HEPA filter were installed in place of a traditional furnace filter, airflow in your ventilation system would grind to a halt and it could damage the system. There is just not enough power in your ventilation system to circulate the air in your house through a HEPA filter. The need to balance filtration with airflow is why traditional furnace filters are so inefficient, but there are much more efficient filters and external add-on filtration systems available that balance airflow with filtration and do a much better job of filtering out allergens and other small particles as your ventilation system runs.
Electrostatic filters are based on the fact that most allergens and other particles in the air have a positive charge. While the filtration media is not much finer than a top-of-the-line traditional furnace filter, they are built with filtering materials that have a permanent negative charge. In addition to their ordinary filtering ability, electrostatic filters attract positively-charged allergens and other small particles to the negatively-charged filter much like a magnet. Electrostatic filters come as permanent washable filters and as quarterly disposable filters. It's important to clean permanent electrostatic filters monthly and replace disposable filters quarterly in order to maintain their effectiveness against small particles. Once the negatively-charged fibers get covered in dust, their ability to attract particles with an opposite charge is diminished, and more and more small particles like allergens can get through.
* Diagram adapted from a paper presented by Kinzer, K.E. and Moreno, R.C., 1997, "Performance Comparison of Residential In-Duct Air Cleaning Devices" at the proceedings of The Tenth Annual AFS Technical Conference.
There are also a few solutions that filter air externally, before it even enters your ventilation system, but they require installation by a HVAC professional and can cost as much as several thousand dollars. Whole-House HEPA filtration systems are one example of external furnace filters. They use a very powerful fan to pull air out of the return duct and through the HEPA filter before feeding it back into furnace.
Another external furnace filtration technology is electrostatic precipitators. Electrostatic precipitators are used to clean the air coming out of factories, but the same technology has grown in popularity in home ventilation systems and some room air cleaners. They are ionizers designed to collect the allergens and other particles from the air once they have been charged. First, the air is passed through an ionizer where the particles gain a particular charge. Then that air is passed between plates with the opposite charge that attract the charged particles. Electrostatic precipitators have one major drawback though; they rapidly loose effectiveness as dust builds up on the plates. Studies have found that plates need to be cleaned as often as every week in order to maintain their effectiveness.
There are several other filtering technologies on the market: activated charcoal, zeolites, UV light and ozone. They are ineffective at filtering out small particles, but are often teamed with the filters we've discussed above to provide added protection against microorganisms, gases, and odors.
Activated carbon and zeolites are primarily used to filter odors, gases and other volatile organic compounds (commonly referred to as VOC's) out of the air. They are often teamed with other filters in air cleaners to provide the added benefit of removing things like cigarette or pet odors, paint fumes and cleaning chemicals out of the air.
UV lights are commonly used in the air purification systems at hospitals and other medical facilities because of their ability to kill bacteria, viruses, mold and other microbes. When the microorganisms in the air are exposed to it, the UV light penetrates the organisms' membranes and alter their DNA. The altered DNA causes the microorganisms to no longer be able to reproduce and once bacteria and viruses lose the ability to reproduce they are no longer harmful.
Warning: Ozone generators don't filter anything out of the air, and have been widely debunked as a residential air cleaning technology. For more information about the ineffectiveness and the dangerous health consequences of ozone generators the EPA has put together an excellent publication, "Ozone Generators that are Sold as Air Cleaners: An Assessment of Effectiveness and Health Consequences". Both negative ion generators and electrostatic preciptators may produce some ozone as a by-product of their air cleaning. So when you're considering these units, it's important to make sure that they don't produce unsafe levels of ozone.
Where to Go From HereDuring the course of our 15 years in the business, we've seen a lot of research and received feedback from thousands of customers. That had lead us to believe that for most people the best strategy for cleaning the air in your home often involves a combination of technologies at two different levels - the whole house and in individual rooms.
For the whole house, it's important to use a high quality furnace filter to prevent allergens and other particles from being scattered throughout your home as your heating and/or cooling system circulates air. If you don't have central air, then it is just as important to replace the filters in your window A/C units regularly.
The next step is to target the individual rooms where you and your family spend a lot of time. Bedrooms are the first area that come to mind, since most people spend more time in their bedroom sleeping than in any other room. For cleaning the air in individual rooms, National Allergy recommends HEPA air cleaners for most people, because they are the most effective filters at trapping particles and getting them safely out of your environment. But in order to clean the air, it is absolutely essential that the HEPA air cleaner be suited for the size of the room you wish to clean. To clean the air throughout a room, it must be able to circulate all the air in the room through the air cleaner at least 6 times an hour. All air cleaners in the National Allergy catalog and website list the maximum effective room size, but we've also put all that information together on a single chart, National Allergy's Air Cleaners at a Glance, to make it easy for you to find the right air cleaner for your room.
Our Austin Air Cleaners are a perfect example of the same sort of complementary technologies combined to clean the air in individual rooms. With over 15 pounds of activated carbon and zeolites and a HEPA filter, Austin Air Cleaners do an unparalleled job of providing refreshing air cleaned of particles, chemicals and odors in rooms up to 20 x 25'. To top it off, the filters only need to be replaced every 5 years under normal circumstances and all Austin Air Cleaners come with free ground shipping for your entire order!
And finally, remember that if you are dust mite allergic, placing an air cleaner in your bedroom will bring you only minimal relief unless you encase your bedding as well. Sleeping with your face so close to bedding filled with the allergen is something that no air cleaner can overcome.
If you have specific questions about air cleaners, e-mail us at firstname.lastname@example.org and we'll do our best to help.
Stay tuned next month for a look at Pet Dander Allergies, another exciting coupon, more exclusive offers, and another chance to win an Austin Air HM-400 Air Purifier.
National Allergy's Air Cleaners at a Glance
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