• Minimum Efficiency Reporting Value
• Understanding MERV

What is HEPA?

• High Efficiency Particulate Arresting [Filter] has to meet more demanding US DOE standards than a high MERV air filter.
• True HEPA rated air filters have a MERV of 17-20.
• A HEPA filter is required to remove at least 99.97% of airborne particles down to 0.3u in size (in diameter or in their longest dimension). Any filter, high MERV or HEPA, can be expected to filter out larger particles with an efficiency above its rating.

How often should I change my filters?

• NAFA Best Practice Guidelines