Air Filters

With all the potential adverse health effects from the quality of air in the home it is natural to want to protect yourself and your family from the chemicals being released into the air (off-gassing). Filtering the air we breathe is one of the best ways to remove harmful agents. There are so many types of filters on the market today; knowing which one to buy can be confusing. It is important to do your research and purchase a good quality filter.

Up to 95% of the particles found in the air are small and not visible. When selecting a filter, look for the percentage capture (e.g. 95% or more) of total number respirable particles. Respirable particles are 10 microns in size or less (smaller than the thickness of a human hair). A typical furnace has a one inch thick rough filter which can remove most of the large particles. Pleated filters and mesh electrostatic filters are available for the furnace to help improve efficiency but are not very effective at trapping small particles.

To remove small particles, a HEPA (high-efficiency particulate air filter) or an electronic filter can be installed on your furnace. A HEPA filter can remove up to 98% of the small particles including ones that are 0.3 microns in size. Electronic filters can remove even smaller particles but are not very effective at removing large particles. These filters may require weekly cleaning to maintain good performance as both filters can become quickly clogged with larger particles. A rough filter can be installed in front to prescreen out the big particles. Please note that washing and vacuuming filters will expose you to concentrated contaminants. Cleaning the filter outdoors and with a mask can help protect your lungs. It is important to note that filtration tends to work best the closer it is to the person. Many people do not permanently live in their basements by the furnace so portable room filters might be considered as they are more effective.

The ability of filters to remove odours is often a concern. Carbon and some chemisorbent filters can remove gas molecules including formaldehyde and other volatile organic compounds. Carbon filters are best compared by weight. The heavier the filter the more gas molecules (odours) it will remove.

Ultraviolet light (UV) generators are advertised as a method for purifying the air in your home. These are not filters, nor are they a substitute for a good filter. These units can kill bacteria and viruses but their low efficiency filters are mainly to keep dust off of the UV bulb. Ozone generators have been shown to be beneficial in combatting mold, but these are also not air filters.

Below is a more detailed description of the potential filter types available for the home constructed by PuraHome, Air and Water Purification Specialists. A chart for comparative analysis has also been included.

(http://www.purahome.com/ 40 Secord Drive, Toll Free: 1-866-670-PURA (7872)  Telephone: 905-934-3168 )

Plasmawave 

Plasma is a charged gas. An alternating electrical discharge creates positive hydrogen ions and negative oxygen ions. These Plasma Ions known as PlasmaWave shoot into the air. They naturally seek out and surround allergens such as dust mites, bacteria, viruses and spores. When the PlasmaWave combines with water in the air, hydroxyls are created. Hydroxyls have been studied extensively all over the world including NASA and the US Army. Hydroxyls will surround the allergens and rob them of hydrogens in order to reform water. This renders the allergen inactive as shown by protein structure testing. The plasma also has the ability to reduce many airborne organic pollutants in the air in to simpler nontoxic substances such as carbon dioxide and water. These systems are usually portable and can be moved from room to room.

Ozone Systems 

Ozone is a strong oxidizer. Ozone is unstable and thereby easily gives an oxygen atom to alter the chemical composition of gases by oxidizing them. It has little or no effect on solid particles although it may halt the growth of mold and bacteria and purify areas of toxins by oxidating them much like oxidized steel (rust), when used in high concentrations. Ozone is often referred to as “energized oxygen” or “pure air” suggesting that ozone is a healthy kind of oxygen. The truth is that Ozone is a toxic gas with vastly different chemical and toxicological properties from oxygen. Ozone can be harmful to and irritate the respiratory system. It is also the primary component of smog. Both the United States Environmental Protection Agency and Health Canada DO NOT APPROVE GENERATORS FOR USE IN OCCUPIED SPACE. (N/A for medical ozone applications)

UV Lights 

Ultra Violet lights (germicidal lamps) or UV systems come in both a hot (8,000 hours life) and cold plasma (rate 36,000 hours life) lamp system. They produce a specific wavelength that has the ability to affect microbiological contaminants like mold and bacteria and to keep it from replicating. UV has no effect on solid particles and it does NOT remove anything from the air stream. UV lights are normally placed in the return air stream. It is important to understand that the speed of the air passing by the lights can minimize the effectiveness of the UV lights. Placing a UV light at or near the cooling coils may work better as the light can irradiate this moist area all the time and help in minimizing the growth of mold or bacteria in the coils. Some UV lights have an additional wavelength that can split oxygen to create short-term ozone that will help sanitize the coils more efficiently as well as reduce spores and odours. If designed properly, the ozone will have dissipated quickly in the cold air return. UV lights are an ancillary piece of equipment and should always be used in conjunction with an air filtration system

Ion Generators 

These devices produce negative ions that charge the particles in the air. The charged particles then attach themselves to both a positive and neutral surface area. This could be a wall, floor, furniture, ceiling, etc. Once the particles lose their charge, they will become airborne again.

There are many options available and many items to consider when selecting an air filter. Make sure to be well informed prior to making a purchase in order to protect your home efficiently. In addition to getting an air filter, there are some steps you can do as well. Open the windows in new homes and new cars for a few days to allow the formaldehyde and VOCs to be off gassed into the air. Bring greenery into the home, especially plants that help purify the formaldehyde specifically (e.g. Rubber plants). Through the soil, greenery can be a source of mold. By covering the soil with tin foil this problem can be reduced. Purifying the air we breathe can help reduce respiratory problems, asthma, allergies and long-term adverse effects.

References:

  1. http://www.calgaryallergy.ca/Articles/English/Adobe/Air%20Filter%20Review.pdf
  2. http://www.purahome.com/articles/files/Air_Cleaning_Technology_Comparison-_alternate_systems.pdf
  3. http://www.air-purifier.org/comparisons.html
  4. http://webecoist.com/2009/04/08/air-purifying-plants/