Design Considerations and Operation:
Efficiency measures the ability of the
filter to remove the fine particles.
ASHRAE efficiencies of between 10
percent and 40 percent should remove
20 percent to 40 percent of the 1
micron particles in the air, but hardly
any of the 0.3 to 0.5-micron particles.
ASHRAE efficiencies of 80 percent to
95 percent can remove 50 percent to
70 percent of the 0.3-micron particles.