Table 3

Characteristics and pool attendance of children from 15 different primary schools in Brussels

							Pool attendance
School no.	n	Age (years)	Sex ratio	White (%)	Pets (%)	ETS (%)	Start	Min/wk	Pool height (m)	PEF15 (%)	PEF10 (%)	Total asthma (%)
The letters give the weekly duration of pool attendance during kindergarten when the latter was different from that in later grades: *30 min; †6 min; ‡15 min; PEF10, prevalence of children with a 10% post-exercise reduction of peak expiratory flow; PEF15, prevalence of children with a 15% post-exercise reduction of peak expiratory flow. Total asthma is the sum of the prevalence of PEF10 plus the prevalence of EIB negative children but treated for asthma. k, kindergarten (ages 5–6 years); p1 to p5, first to fifth grade of primary school.
1	146	10.1 (7–13)	0.81	25	34.0	53.4	k	15	11	6.16	10.96	19.58
2	75	10.5 (9–14)	1.21	40	33.0	50.7	p1	15	11	2.66	2.67	11.11
3	50	10.5 (9–14)	1.00	60	50.0	60.0	k	12.5	11	0	2.00	8.00
4	88	10.6 (9–13)	0.80	99	25.0	42.0	k	15	11	7.95	11.36	12.5
5	49	10.1 (8–12)	1.33	40	28.6	34.7	k	15*	11	6.12	10.2	18.37
6	109	10.9 (9–13)	1.02	10	40.0	55.0	k	20	11	3.66	11.0	14.81
7	171	10.3 (8–13)	1.09	90	45.6	56.7	p5	30	11	2.92	6.43	14.04
8	97	10.8 (9–13)	1.18	74	47.4	48.5	k	15†	7	6.2	6.36	12.77
9	84	10.5 (9–14)	1.33	90	71.0	56.0	k	30‡	6	9.5	26.0	30.49
10	182	10.3 (9–13)	1.25	88	61.5	51.1	p1	30	8	0.55	2.19	8.57
11	110	10.6 (9–13)	1.08	10	75.4	34.0	p2	15	8	0.91	2.72	5.45
12	119	10.6 (8–13)	0.92	25	38.7	45.4	k	15	8	1.68	5.88	13.45
13	80	11.0 (8–14)	1.19	40	37.5	32.0	k	30	8	7.5	11.26	14.10
14	228	9.1 (7–12)	0.98	80	56.1	50.9	k	30	15	7.02	12.7	20.10
15	293	8.9 (6–12)	1.26	99	53.9	42.7	k	15	15	3.41	7.2	9.63