The air we breathe is important to overall health. That’s more apparent now than ever before, and at Aprilaire we’re focused on getting you and your family the information you need to stay healthy during this time.
Healthy Air In The Home With MERV 16 Filters
The air inside your home can be 5x more polluted than the air outside. This is important to consider if you’re in a part of the United States using stay-at-home orders to reduce the spread of the COVID-19 virus.
The next area to consider is air filtration. While there are a variety of options for purifying your air, today we’ll look at the effectiveness of MERV 16 filters, which can capture both virus-sized particles and airborne allergy and asthma triggers.
What Exactly is MERV and how does the rating system work?
MERV, otherwise known as Minimum Efficiency Reporting Value, is a measurement scale that rates the effectiveness of filters at trapping airborne particles. The scale ranges from 1-16, with 16 being the most effective.
Here’s an in-depth description of the process used to determine MERV, from the National Air Filtration Association:
“An air filter’s performance is determined by measuring the particle counts upstream and downstream of the air-cleaning device being tested.
A laboratory aerosol generator, which operates much like a paint sprayer, is used to create a challenge aerosol of known particle size in the air stream. This will generate particles covering the 12 required particle size ranges for the test. The challenge aerosol is injected into the test duct and particle counts are taken for each of the size data points.
The filter’s performance, on each of the twelve particle sizes, during the six test cycles (a total of 72 value or calculated value) is determined. For each value or calculated value, the filtration efficiency is stated as a ratio of the downstream-to-upstream particle count. The lowest values over the six test cycles are then used to determine the Composite Minimum Efficiency Curve. Using the lowest measured efficiency avoids the misinterpretation of averaging and provides a “worst case” experience over the entire test.”
Air Filters and Viruses
The size of contaminants and particles are usually described in microns, a metric unit of measure where one micron is one-millionth of a meter:
- 1 micron = 10-6 m = 1 μm
The particular strain of coronavirus that’s causing COVID-19 (known as SARS-CoV-2) measures between .05 and .2 μm in diameter. (One study found it to be between .07 and .09 μm.)
The diagram below demonstrates that MERV 16 filters trap up to 96% of virus-sized particles*, to help prevent the proliferation of airborne viruses in the home.
1Solid lines represent MERV test data; dashed lines represent calculations for ultra-fine particles
*Contaminants removed based on air passing through the filtering system.