Having said that, the obvious exception is when cigarette, pipe or cigar smoking occurs on a regular basis. Now the pollution can’t be missed, you can see it and you can smell it. The health concerns regarding smoking are well known and possibly beaten to death, so we won’t get in to that. Not so obvious is the health impact of dirty interior air when we don’t notice it. Medical experts have concluded that symptoms ranging from headaches, asthma, bronchitis, allergies and cancer among others, may likely be attributed to polluted interior air.

The next reason to use a furnace filter or air conditioning filter is to keep your heating and cooling system operating as it was designed and to prolong its life. For an air conditioning unit to operate at its peak efficiency it needs to be kept clean. The evaporator is the component in your system in which the air passes directly over and is cooled and returned to your living space. The surfaces of the evaporator are normally very cold and therefore wet with condensation. The moisture in the air condensates on the evaporator and subsequently drains to the exterior of the building. Imagine blowing dirty air across the cold wet surfaces of the evaporator. How long do you think it takes for the dirt to completely cover this wet surface? Once dirty, the evaporator loses efficiency and may begin to support mold and bacteria growth, after all it is a dark moist environment.

The last reason for using an air conditioning filter and furnace filter is to help keep your house clean. Look at it this way, every time your air conditioner or furnace runs it is like someone is vacuuming the air of dust, dirt or worse. All of this for only a couple bucks per month, seems like an obvious choice, your air must be filtered. What may not be obvious is which furnace filter and air conditioning filters should be used, we will try to help with that decision.

The average person takes about 20 breaths per minute, which works out to almost 30,000 breaths per day. Clearly this is an activity which we spend considerable time, if not effort. Each one of those breaths contain dust, bacteria, germs, soot, fumes, pollen and many other harmful material. It is true that our bodies have some built in filtration functions but why overtax the body? Estimates vary widely but some suggest interior air can be 10 or more times as polluted as outside air. If the man made indoor pollution is that concentrated should we really believe our bodies were designed for that? Not likely.

We humans live in closer proximity to each other than ever before. That proximity intensifies the airborne particles from vehicles, other people, animals, manufacturing and other sources. Some well known airborne diseases are influenza, diphtheria, hay fever, tuberculosis, colds, viruses, pneumonia, scarlet fever, measles, etc.

When we think about dust its not just dust it is made up of a vast array of materials. Most of the materials are not good, such as; soot, dander, sand, smoke, fibers, insects, hair, not to mention chemical fumes. The US Weather Service estimates that one cubic inch of air could contain as much as 100,000 particles of dust. Worse yet, each piece of dust can contain thousands of germs.

A human living indoors is a relatively new phenomenon, at least with more or less sealed buildings. Only one hundred years ago our buildings had no air conditioning, central heat, weather-stripping, thermal pane windows, insulation or any of the modern products currently used to effectively seal the inside air from the outside.

Health statistics show that incidence of asthma which is known to be aggravated by air pollution is rising dramatically in the USA. The health risks are too great to ignore the regular use and replacement of a good air conditioning filter

Smoke will remain suspended in the air while the others will settle after a time. Specialized air cleaners are available and for some people these will provide a real benefit. For most people the filtration products available to work with your central air system are sufficient.

In order to clean the air effectively and allow the air conditioning system to operate efficiently and as it was designed, the following criteria should be considered:

- The air filter should be easy to change or clean or should be of a self cleaning type.
- The air filter should have the capacity to trap and hold a large amount of contaminant without adding too much resistance to the air flow.
- The air filter should be efficient in trapping and holding dust, fumes, pollen, bacteria and smoke which are present in most interior environments.
- The air filter should be able to operate effectively and efficiently with various equipment which may have varying air velocity characteristics.
- The air filter should leave the filtered air clean from contaminants including those which are added in the manufacturing process to improve performance.

This may seem to be an intimidating list of requirements but there are many products commonly available which will meet or exceed these requirements. Unfortunately, there are just as many or more which do not meet the requirements. A visit to your local retailer will likely provide a wide range of available products form those which are very suitable to those that are almost useless.

The information contained in this site should provide you with enough valuable information to make the selection of the right air conditioning filters much easier.

One factor to consider is air flow through the system. Air conditioning systems are designed to operate most efficiently with the airflow remaining within the designed range. More air flow is not good but is difficult to achieve but low air flow is not good either and is quite easy to achieve. Leaving a dirty air filter in place may result in low air flow and possibly cause the system to malfunction. In some cases, using an air conditioning filter that is too restrictive for your system may cause low air flow problems as well.

In the old days the filters were commonly the fiberglass variety which might equal a MERV 1 or 2. These provide very good flow but not much filtration beyond the sizable particles in the air. They will help to prevent the evaporator from getting too dirty too fast but they don’t do much to improve air quality. On the other end of the spectrum are the MERV 15 or 16 filters which do an excellent job cleaning the air but are too restrictive for most home systems.

If you are wondering what MERV to try keep these recommendations in mind;
 -ASHRAE recommends MERV 6 or higher
 -US Department of Energy recommends MERV 13
 -Leadership in Energy and Environmental Design, LEED recommends MERV 8 at a minimum

Keep the air flow issue in mind and if possible start with a MERV 6 and work up if no system  performance problems are noted. Most importantly, change you air conditioning filters regularly according to the manufacturer’s recommendation.

We pass through the grill and immediately encounter the dreaded Air Conditioner Filter. No worries for us though since we are pure and clean and pass through the filter unscathed. We are moving fast and it is almost completely dark inside the tube where we find ourselves traveling. We don’t travel too much further before we run into a series of cold, wet metal plates. It’s turbulent and noisy but we emerge from the turbulence quickly and we are now about 25 degrees colder and a little drier.

Our journey continues through a tube which has some quick turns and junctions, in the distance we notice a little light. With the increasing light, we see the inside of the tube is nice and clean, not a bad place to travel. Soon we pass through another grill but much smaller that the first one. We’ve been deposited in the kids room where all is quiet, a rare thing we’re told. We float around the room a bit and as we do we notice what sounds like light breathing. Sure enough the baby is taking her afternoon nap and we continue to drift above her. The room is pleasant and clean, some light music plays in the distance.

A little more drifting and we find ourselves gently pulled into the baby’s nose back into the darkness and into her lungs. We are warm and moist again and happy to be clean and healthy for her to breathe.

Good thing her dad uses a good air conditioning filter.