When it comes to air filtration, MERV stands for Minimum Efficiency Reporting Value. It is a nationally recognized system used to measure the ability of air filters to trap particles of a specific size. The higher the MERV rating, the more effective the filter is at trapping particles. For example, a MERV 11 filter needs to stop 20% of particles smaller than 0.3 to 1.0 microns, while a MERV 13 filter needs to stop half of those particles.
ASHRAE recommends MERV models 13 and 14 for optimal air filtration. In addition to MERV ratings, FPR stands for Filter Performance Rating. This rating system is used to measure the effectiveness of air filters in removing airborne particles from the air. The higher the FPR rating, the more effective the filter is at trapping particles. For instance, an FPR 8 filter will be more than enough to filter dust and allergens and eliminate dozens of toxic gases that will pass directly through a MERV 13 filter. When selecting an air filter, it's important to consider both the MERV and FPR ratings.
A higher MERV rating may mean slightly more restricted airflow; however, most current HVAC systems are capable of handling a MERV 11 air filter without additional stress on the system. Newer units shouldn't have airflow problems with higher MERV ratings, although older models can work harder with a MERV 13 filter installed than when they originally had a MERV 6 filter in the air intake. In addition to selecting an appropriate air filter, it's important to replace dirty filters often enough. Depending on the MERV classification, effective area of the filter and amount of particles that enter your home, this could be as often as once a week or two. Fortunately, peace of mind is priceless and if you think that a high MERV filter would provide that, it's worth considering. Finally, if you're looking for an alternative to buying an air filter, you can make your own N95 with a Merv 16 filter.
However, it's important to note that if you buy to wash an alcohol, you could very well be creating some strange, weird and fun chemicals. In these cases, it's best to use sunlight to disinfect them as this will not break the tall Merv filters and release any unwanted chemicals.
