Importance of MERV

Minimum Efficiency Reporting Value, commonly known as MERV rating, is a measurement scale designed in 1987 by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) to rate the effectiveness of air filters.

MERV
Min. Particle Size
Typical Controlled Contaminant
Typical Application
1-4
> 10.0 μm
Pollen, dust mites, cockroach debris, sanding dust, spray paint, textile fibers, carpet fibers.
Residential window AC units
5-8
10.0 - 3.0 μm
Mold, spores, dust mite debris, cat and dog dander, hair spray, fabric protector, dusting aids, pudding mix.
Better residential, general commercial, industrial workspaces
9-12
3.0 - 1.0 μm
Legionella, humidifier dust, lead dust, milled flour, auto emission, particulates, nebulizer droplets.
Superior residential, better commercial, hospital laboratories
13-16
1.0 - 0.3 μm
Bacteria, droplet nuclei (sneeze), cooking oil, most smoke and inseticide dust, most face powder, most paint pigments
Hospital and general surgery
17-20
< 0.3 μm
Virus, carbon dust, sea salt, smoke
Electronics & pharmaceutical manufacturing clean room