Table 4.

IAQ measurements on a seasonal basis for combined control and treatment groups. Otherwise as Table 3.

Statistic		N	Ave	SD	Med	p-value^a
PM (µg/m³)	Spring	14	34.2	30.3	20.1	<0.001
	Summer	22	39.3	19.4	40.6
	Fall	35	30.3	24.5	20.3
	Winter	44	18.9	17.0	11.9
0.3–1.0 µm PNC (#/liter)	Spring	14	64,643	49,408	48,003	<0.001
	Summer	19	109,315	75,134	84,037
	Fall	35	80,433	55,350	69,176
	Winter	45	48,903	53,129	32,143
1–5 µm PNC (#/liter)	Spring	14	1,252	1,480	702	0.019
	Summer	19	1,771	1,822	1,458
	Fall	35	1,797	1,243	1,474
	Winter	45	1,159	1,204	590
CO₂ (ppm)	Spring	14	1,096	387	995	0.112
	Summer	21	1,085	427	929
	Fall	41	1,297	501	1,269
	Winter	47	1,058	455	920
AER LR (h⁻¹)	Spring	11	0.48	0.36	0.40	0.270
	Summer	21	0.88	0.60	0.84
	Fall	33	0.71	0.55	0.60
	Winter	38	0.79	0.49	0.73
AER BR (h⁻¹)	Spring	8	1.38	0.91	1.19	0.949
	Summer	20	1.94	2.12	1.30
	Fall	34	1.74	1.59	1.22
	Winter	38	1.53	0.99	1.23

p-value from Mann Whitney test.