HEPA vs. MERV
If you're looking for an air filter for your home, it can get confusing quickly. You'll come across both MERV and HEPA rated filters. It's hard to know which one you might need. If people in your home are bothered by allergies or asthma, cleaning irritating particles out of the air can help them breathe easier.
MERV stands for Minimum Efficiency Reporting Value. These filters are rated on how small of a particle they can filter out of the air. The numbers range from 1 to 16, and the higher the number, the better. A low ranking filter is rated 1-4 MERV, and medium filter falls into the 5-13 MERV range, and high-efficicency filter will range from 13 to 16 MERV. The high-end filters can filter particles as small as 0.3 microns with 75 percent efficiency.
HEPA stands for High Efficiency Particulate Air filters and they are super-efficient. They will range from 17-20 MERV. HEPA filters meet standards that remove at least 99.97% of airborne particles down to the size of 0.3 microns. These levels of filters are used in hospitals to stop the spread of disease-causing organisms.
For the ultimate in indoor air quality, HEPA level filtration incorporated with a balanced ventilation system is the way to go. A balanced system brings in fresh outdoor air, runs in through the HEPA filter before delivering it to the home. Then the exhaust system removes stale air, with any particles that may have been brought indoors on people's clothing or pets.
If you're thinking about adding HEPA level filtration, work with your HVAC professional to find the best system for your situation.