Filtering the air in your home is an important method to enhance the treatment of your allergies provided by your physician. Unfortunately, not enough research has been done to adequately understand the scope of the problem. There is a lot of confusing information out there when it comes to which air filter or air purifier is best, if any. This article is meant to help you understand a little better what to look for in improving the air quality in your home.
What Do I Look for in Air Filters?
System filters are rated by the American Society of Heating, Refrigerating, and Air-conditioning Engineers (ASHRAE). ASHRAE assigns a minimum efficiency reporting value (MERV) to determine the quality of air filters. The higher the MERV value, the better filtration one can expect.
After you find a high MERV rating then you need to make sure the filter has an adequate holding capacity to prevent it from becoming fully loaded quickly. For example media filters become more efficient as they load where as electronic cleaning devices that need to be washed or wiped rapidly lose efficiency as these plates that generate the electrostatic charge become coated with particles. In my estimation media filters may have a better long term benefit. There are different Heating, Ventilation, Air-conditioning (HVAC) filters available. You can purchase disposable filters with a recommendation of MERV 6 or higher.
Types of Air Filters:
- Panel Filters: These have very low MERV ratings if made of fiberglass or synthetic material. Multipleat extended surface are the most common type high-efficiency filters. The most effective are of nonwoven materials such as polyolefin. You should change these out every 3 months. Washable filters are less effective and can leave residual damp dirt that can provide a substrate for mold and bacterial growth.
- HEPA HVAC Filters: High Efficiency Product is a generalized term for these types of filters. Beware of HEPA-type or HEPA-like as these are a misuse of the terms and usually do not meet the necessary performance requirements. These are generally thought to be expensive because of the requirements of bypass systems to allow proper air intake.
- Powered Electronic Filters (EACs): These are small electrostatic precipitators in which the entering dust and air are ionized in a high-voltage electric field. These tend to lose efficiency quickly as they become covered in dust thereby compromising performance and can produce low levels of ozone.
- Composite Component Systems: These are a mix of technologies that require continuous air flow which leads to increased energy demand and potential failure of the blower motor of your AC unit if not maintained regularly.
What Do I Look for in Portable Room Air Cleaners?
Portable room air cleaners are rated in accordance with the Association of Home Appliance Manufacturers (AHAM). The problem is a third party is required to assess the efficiency of these devices and it is voluntary and therefore not usually done.
- Ionizer Air Cleaners or Purifiers: Like the EACs have the disadvantage of filling quickly with particles and producing ozone which can cause a worsening of asthma.
- HEPA Room Air Cleaners: These have been shown in studies to be somewhat helpful in animal allergy homes. These have also been shown to be partially helpful in pollen allergic patients. But these studies have been small and felt to be inadequate to fully understand. It is my experience that these maybe helpful but need to be cleaned regularly.
- Non-HEPA Room Air Cleaners: Air cleaners that contain disposable or washable filters increase cost and allow for mold and bacterial growth as listed earlier with HVAC filters.
To summarize, in choosing the optimal choice of cleaning device one should consider initial cost and ease of regular cleaning and maintenance. Portable room air cleaners with HEPA filters, especially those that filter the breathing zone during sleep, appear to be beneficial. Those with forced air HVAC systems should maintain a regular maintenance schedule. The best filters as listed above should be the high-efficiency disposable filters with the MERV above 6 in the multipleat variety. However, further research is needed to better define these products.