ASHRAE Standard 52.2				ASHRAE Standard 52.1	Application Guidelines
MERV	Particle Size Removal Efficiency, Percent in Particle Size Range, µm			Dust-Spot Efficiency Percent	Particle Size and Typical Controlled Contaminant	Typical Applications	Typical Air Filter/Cleaner Type
	0.3 to 1	1 to 3	3 to 10
20	= 99.999	in 0.1 - 0.2 µm particle size		-	< 0.3 µm	Electronics manufacturing	HEPA/ULPA Filters*
					Virus (un attached)	Pharmaceutical manufacturing
19	= 99.999	in 0.3 µm particle size		-	Carbon Dust	Carcinogenic materials
18	= 99.99	in 0.3 µm particle size		-	Sea Salt
17	= 99.97	in 0.3 µm particle size		-	All combustion smoke
16	> 95	> 95	> 95	-	0.3-1 µm	Superior commercial buildings	Bag Filters - Non supported (flexible) microfine fiberglass or synthetic media, 12 to 36 inches deep.
					All bacteria	Hospital inpatient care
					Droplet nuclei (sneeze)	General surgery	Box filters - Rigid style cartridge, 6 to 12 inches deep.
					Cooking oil
					Most smoke
15	85-95	> 90	> 90	> 95	Insecticide dust
14	75-85	> 90	> 90	90-95	Most face powder
13	< 75	> 90	> 90	80-90	Most paint pigments
12	-	> 80	> 90	70-75	1-3 µm	Superior residential	Pleated filters - Extended surface with cotton or polyester media or both, 1 to 6 inches thick.
					Legionella	Better commercial buildings
					Humidifier dust	Hospital laboratories	Box Filters - Rigid style cartridge, 6 to 12 inches deep.
					Lead dust
11	-	65-80	> 85	60-65	Milled Flour
10	-	50-65	> 85	50-55	Auto emission particles
9	-	< 50	> 85	40-45	Nebulizer drops
8	-	-	> 70	30-35	3-10 µm	Better residential	Pleated filters - Extended surface with cotton or polyester media or both, 1 to 6 inches thick
					Mold	Commercial buildings
					Spores	Industrial workspaces	Cartridge filters - Viscous cube or pocket filters
					Dust mite body parts and droppings
					Cat and dog dander		Throwaway - Synthetic media panel filters
					Hair spray
7	-	-	50-70	25-30	Fabric protector
6**	-	-	35-50	< 20	Dusting aids
5	-	-	20-35	< 20	Pudding mix
4	-	-	< 20	< 20	> 10 µm	Minimum filtration	Throwaway - Fiberglass or synthetic media panel, 1 inch thick
					Pollen	Residential window air conditioners
					Dust mites		Washable - Aluminum mesh, foam rubber panel
					Cockroach body parts and droppings
					Spanish moss		Electrostatic - Self-charging (passive) woven polycarbonate panel
					Sanding dust
3	-	-	< 20	< 20	Spray paint dust
2	-	-	< 20	< 20	Textile fibers
1	-	-	< 20	< 20	Carpet fibers