Table 2. Comparison of the Number of Days Exceeding WHO AQG Standards by Group.

	Mockup purifier (total of 924 days*)	Active purifier (total of 924 days*)	p value†
Bed room
PM2.5 (>25 μg/m3)	239 (25.9)	58 (6.3)	<0.001
PM10 (>50 μg/m3)	94 (10.2)	18 (2.0)	<0.001
Living room
PM2.5 (>25 μg/m3)	72 (7.8)	22 (2.4)	<0.001
PM10 (>50 μg/m3)	8 (0.9)	14 (1.5)	0.200

PM, particulate matter; WHO AQG, World Health Organization air quality guideline.

^*Total days: 22 sites (per group)×42 days (air purifier operation period), ^†p-value was calculated by chi-square test.