Table 2.

Colony count and its distribution at 48 hours in three different experimental conditions

Experimental condition	Time point (min)	UVGI	Ventilation	AC	Temperature (°C)	Humidity (%)	Total colonies (CFU/100 L)	Diphtheroid (CFU/100 L)	Bacilli sp. (CFU/100 L)	Staphylococcus species (CFU/100 L)
Scenario A (normal condition)	0	Off (1)	On	On	20.3	48	351	310	15	25
	30	On	On	On	20.7	49	3	0	0	2
	60	On	On	On	21.4	49	2	0	0	1
	120	On	On	On	21.9	47	1	0	0	1
	180	On	On	On	21.8	47	0	0	0	0
	240	On	On	On	21.8	48	3	0	1	0
	300	On	On	On	21.2	48	2	0	0	1
	360	On	On	On	20.8	49	4	0	3	0
Scenario B (abnormal condition)	0	Off (1)	Off (2)	On	19.3	56	~1000	40	5	~900
	30	On	Off	On	19.2	53	7	0	0	7
	60	On	Off	On	19.1	53	1	0	0	1
	120	On	Off	On	19.3	52	7	0	0	7
	180	On	Off	On	19.1	50	3	0	0	3
	240	On	Off	On	19.6	49	5	0	0	5
	300	On	Off	On	19.8	49	1	0	0	1
	360	On	Off	On	19.9	50	2	0	0	2
Scenario C (abnormal condition)	0	Off (1)	Off (2)	Off (3)	22.5	43	99	58	1	39
	30	On	Off	Off	23.4	46	6	2	0	4
	60	On	Off	Off	25.1	46	5	0	0	5
	120	On	Off	Off	26.8	44	3	0	1	2

UVGI, ultraviolet germicidal irradiation; AC, air conditioning; CFU, colony forming unit.

⁽¹⁾UVGI was activated only during the test periods;

⁽²⁾Ventilation was deactivated 2 hours before the test;

⁽³⁾AC was deactivated immediately before the test.