The acronym OEM stands for Original Equipment Manufacturer. This means that the product was manufactured by the original company that produced the product. For instance. If you have a Holmes air cleaner you would purchase a replacement filter that was manufactured by Holmes for Holmes air cleaner products. Other companies make replacement filters however, many of the generic knock-off's or fake brand name filters may be of inferior quality in order to get the price down. It may be in old cliche but you do usually get what you pay for. FiltersUSA provides genuine OEM products together with some generic products that meet or exceed the manufacturers specifications. Preserve your warranty and look for OEM products.

The MERV System (Minimum Efficiency Reporting Value) was instituted to provide minimum efficiency values. When you first install your new filter, its efficiency is at its lowest point. That's because it hasn't built up enough dust and particles on the filter to help trap more dust and particles.

The MERV Rating will give you a worst-case scenario for the lowest amount of efficiency you can expect from your filter. This MERV System also measures the size of the particles a filter can trap. The scale that the MERV System uses can range from a MERV 1 to a MERV 16 (95%+ ASHRAE filter). The MERV System is an excellent tool when you know which contaminants you want to have filtered.

American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) is an international membership organization founded to advance the arts and sciences of heating, ventilation, air conditioning, refrigeration and related issues. This site contains information, guidelines and standards to assist HVAC&R practitioners, and resources for ASHRAE members.

The AHAM seal (usually found on the back of an air cleaner's box) will list three CADR numbers - one for tobacco smoke, one for pollen and one for dust. The CADR indicates volume of filtered air delivered by an air cleaner. The higher the tobacco smoke, pollen and dust numbers, the faster the unit filters the air. When a manufacture obtains product approval for meeting government standards and UL approval, what they state as being 99.97% efficient, has their OEM filter installed. If you would use a generic filter instead, you might get 75% efficiently or using another brand might burn the motor out, not allowing enough air to pass thru the filter. It is always important to look for genuine OEM replacement filters to maintain the efficiency of your air cleaner.

Follow our 2/3 Rule:
You'll always want a unit with a tobacco smoke CADR at least 2/3 your room's area. For example, a 10' x 12' room -120 square feet - would require an air cleaner with a tobacco smoke CADR of at least 80. If your room size is smaller, the unit will simply clean the air more often or faster. If you have ceilings higher than 8', you'll want an air cleaner rated for a larger room.

The HEPA filter was developed during World War II by the Atomic Energy Commission and it was designed to remove and capture radioactive dust particles from the air which might escape and present a health hazard to the researchers. The HEPA filter was specifically designed to protect the Human Respiratory System.

For a filter to be labeled "True" HEPA, it must be certified 99.97% efficient in capturing 0.3 micron (not 0.1 or 0.01 etc..) respirable-size-particles (RSP) according to the U.S. Military Standard MIL-STD-282, commonly known as the DOP test. The reason 0.3 micron is used and no other is because 0.3 micron is the size at which all mechanical filters are LEAST efficient in capturing. Other methods of testing do not give a true picture of efficiencies relative to respirable-size-particle (RSP) capture.

• Human Hair (70 - 100 microns)
• Pet Dander  (0.5 - 100 microns)
• Pollen  (5 - 100 microns)
• Spores from Plants (6 - 100 microns)
• Mold (2 - 20 microns)
• Smoke (.01 - 1 micron)
• Dust Mite Debris (0.5 - 50 microns)
• Household Dust (.05 - 100 microns)
• Skin Flakes (0.4 - 10 microns)
• Bacteria (0.35 - 10 microns)