Higher does not necessarily mean better. Higher grade filters filter more in eac...

		fifteenforty 9 months ago \| parent \| context \| favorite \| on: Installing air filters in classrooms has surprisin... Higher does not necessarily mean better. Higher grade filters filter more in each pass, but can overall provide worse performance as the air flow rate goes down. The air is being recirculated in a portable unit or in a standard domestic ducted heating/cooling situation.