In order to stay safe during the Covid-19 pandemic, we’ve masked up, gotten air purifiers, and upgraded the HVAC systems in the places where we gather. But what exactly is inside those filters?
The answer varies, and not all filters are created equal. In the age of an airborne global pandemic, record-setting wildfires, and devastating air pollution, high-quality air filters are more important than ever. But filter design is a tricky business. You have to find the balance between allowing the good stuff (air) in, while keeping the bad stuff (particles) out. A Connecticut-based company called Lydall produces the specialty fabric that goes inside masks and air filters.
They manufacture nonwoven materials that capture airborne particles such as viruses, allergens, and environmental pollutants. During the pandemic, they have been especially busy making “meltblown” fabric, which is rightly named because it’s made by melting little balls of plastic, reshaping it into fibers, and blowing it onto a conveyor belt. The resulting material is used for medical-grade face masks and larger air filtration systems, such as the HVAC units that circulate and sanitize the air inside buildings.
So, how do you evaluate a filter? There’s an official rating system, called the Minimum Efficiency Reporting value, or MERV rating. The American Society of Heating, Refrigerating, and Air-Conditioning Engineers grades the performance of filters on a scale of 1 to 16 based on the filter’s ability to capture air particles.
Medium efficiency filters (MERV 5 to 13) can remove many nasty particles from the air, including viruses, pet dander, bacteria, and some molds. Until recently, MERV 8 filters were considered just fine. They were the default filter for cleaning outdoor air coming into a building, since they capture most large particles. Now the Environmental Protection Agency (EPA) suggests upgrading to a MERV-13 filter, which is even better at capturing viruses and other tiny particles from circulated air. However, the highest rated filters are so good at trapping everything that they make it difficult for fresh air to pass through. So the goal is to get the right filter paired with the right fan, one powerful enough to pull air through the filter.
As we emerge from isolation and start to get together again, the air filtration systems we put in place now will help protect us against a wide range of air particles. Better indoor air quality just makes sense for the challenges we face today and tomorrow.