Hello! During the wildfires in LA, I’m seeing builds of CR boxes that are 1 filter attached directly to the back of a box fan. Obviously this is an emergency and any filtration is better than none. Volunteers are doing what they can with extremely limited resources. I am curious to know how efficacious these 1 filter box fans are in comparison to the 4 filter models that were originally popularized.
Hello! During the wildfires in LA, I’m seeing builds of CR boxes that are 1 filter attached directly to the back of a box fan. Obviously this is an emergency and any filtration is better than none. Volunteers are doing what they can with extremely limited resources. I am curious to know how efficacious these 1 filter box fans are in comparison to the 4 filter models that were originally popularized.