Table 4.

Particle removal efficiency of different filters.

MERV	Particle removal efficiency ηfilter [%]
	0.3–1 μm	1–3 μm	3–10 μm	Particle-size-weighteda
1	0	0	10	5–7
2	0	0	10	5–7
3	0	0	10	5–7
4	0	0	10	5–7
5	3	17	20	16–18
6	3	17	35	23–28
7	9	17	50	32–39
8	9	20	70	43–54
9	9	35	85	55–67
10	9	50	85	59–70
11	20	65	85	66–74
12	35	80	90	76–82
13	50	90	90	82–86
14	75	90	90	87–88
15	85	90	90	89
16	95	95	95	95
HEPAb	99.9	99.9	99.9	99.9

^aMonte Carlo approach is implemented that adopts uniform probability distribution of particle sizes, i.e. 10-20% in 0.3–1 μm, 20–30% in 1–3 μm, and remaining 50–70% in 3–10 μm.

^bHigh-efficiency particulate air (HEPA) filters.