| ASHRAE 52.2 | ASHRAE 52.1 | ||||||
|---|---|---|---|---|---|---|---|
| Particle Size Range | Test | Particle Size Range, μm | Applications | ||||
| MERV | 3-1 0μm, % | 1-3μm, % | 0.3-1.0μm, % | Arrestance, % | Dust spot, % | > 10.0 Residential light pollen, dust mites | |
| 1 | < 20 | n/a | n/a | < 65 | < 20 | ||
| 2 | < 20 | n/a | n/a | 65-70 | < 20 | ||
| 3 | < 20 | n/a | n/a | 70-75 | < 20 | ||
| 4 | < 20 | n/a | n/a | > 75 | < 20 | ||
| 5 | 20-35 | n/a | n/a | 80-85 | < 20 | 3.0-10.0 Industrial, dust, moulds, spores | |
| 6 | 35-50 | n/a | n/a | > 90 | < 20 | ||
| 7 | 50-70 | n/a | n/a | > 90 | 20-25 | ||
| 8 | > 70 | n/a | n/a | > 95 | 25-30 | ||
| 9 | > 85 | < 50 | n/a | > 95 | 40-45 | 1.0-3.0 Industrial, Legionella, dust | |
| 10 | > 85 | 50-65 | n/a | > 95 | 50-55 | ||
| 11 | > 85 | 65-80 | n/a | > 98 | 60-65 | ||
| 12 | > 90 | > 80 | n/a | > 98 | 70-75 | ||
| 13 | > 90 | > 90 | < 75 | > 98 | 80-85 | 0.3-1.0 Hospitals, smoke removal, bacteria | |
| 14 | > 90 | > 90 | 75-85 | > 98 | 90-95 | ||
| 15 | > 90 | > 90 | 85-95 | > 98 | ≈95 | ||
| 16 | > 95 | > 95 | > 95 | > 98 | > 95 | ||
| 17 | n/a | n/a | ≥ 99.97 | n/a | n/a | < 0.3 Clean rooms, surgery, viruses | |
| 18 | n/a | n/a | ≥ 99.99 | n/a | n/a | ||
| 19 | n/a | n/a | ≥ 99.999 | n/a | n/a | ||
| 20 | n/a | n/a | ≥ 99.9999 | n/a | n/a | ||
Department of Health and Human Services. Guidance for filtration and air-cleaning systems to protect building environments from airborne chemical, biological, or radiological attacks [report on the Internet]. DHHS (NIOSH) Publication No. 2003-136. April, 2003. National Institute of Occupational Safety and Health (NIOSH). [cited 2005 Sept. 1]. Available from: http://www.cdc.gov/niosh/docs/2003-136/pdfs/2003-136.pdf. (18)