Are MERV ratings per-pass through filter or cumulative?
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A MERV13 filter removes greater than 50% of particles sized 0.3 to 1.0um per the chart in the article below. If a particle in this range passes the first time greater than 50% should have been removed. On a second pass, will it be 50% of the remainder? This would imply after the air has been cycled through at least twice a MERV13 h as removed at least 75%, correct?
https://www.greenbuildingadvisor.com/article/understanding-filter-ratings-merv-fpr-and-mpr
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