With the introduction of ISO 16890 to the world (only the United States is left to adpot it) there has been a lot more talk and research about the relationship between air filters and air quality. This discussion has been happening before, but with little emphasis on what particles are actually in the air and how the filter reacts with those particles. Shocking to most people is the most common air filters in the United States (MERV-8, MERV-10, and MERV-11) do a poor job at capturing the most damaging of airborne particles. Here's a chart of particles and how deep they enter our body:
As you can see, the most harm causing particles are also the ones that make-up over 98% of the paricles in the air. What is surprising to most people is that MERV-8 and MERV-10 only capture about 1-4% of all particles and they aren't even tested on particles smaller than 1 micron! MERV-11 isn't much better capturing only about 21-22% of all particles of which only 20% are the sub-micron particles.
It is discouraging to air filter people like us that the current air filter rating system in the United States, ASHRAE 52.2 which produces MERV, is a scale that offers a numerical value of 1-16 and when we are half way through the numerical scale we are capturing well under 5% of particles in the air. THIS IS INCREADIBLY MISLEADING TO CONSUMERS! With the overwhelming majority of air filters used in teh United States being MERV-11 or under is it any wonder why rates of childhood asthma are increasing?
Tight budgets and the mentaility of "we've been using those for years" is especially bad in K-12 schools which are arguably one of the most critical environments for clean air next to hospitals and elderly care facilities because the internal organs of children are still developing.
Knowing how your air filters interact with the air, and what is even in that air, is the first step in better protecting yourself. Many times people will rush to a HEPA filter as a solution for indoor air quality and that's not always recommended or needed. Most indoor air quality issues relating to Particulate Matter (or PM) can be solved by using a filter rated at MERV-13. This efficiency is a good balance of particulate capture by collecting over half of all sub-micron particles, while also not being as expensive, or as costly to operate. Converting to actual HEPA filters in an existing HVAC system likely means a compelte redoing of the filter housings/racks and putting in a larger fan or motor to accomodate the increased airflow resistance of the HEPA. MERV-13 however, is economical, energy efficient, and typically doesn't require an overhaul of an existing HVAC system.
As with anything there are always things to look out for, like the use of synthetic air filter media, but by upgrading to MERV-13 the people that have to work, go to school, or live in that building will be much better protected from those harmful sub-micron particles. If you have more questions or would like some advise, please feel free to contact us - we're here to help.