Early life swimming pool exposure and asthma onset in children – a case-control study

Table 3 Air concentrations of trichloramine at the different swimming pool facilities

	Swimming pool		NCl₃ (mg/m³)						Hours	Proportion
Municipality	identification number	N	Mean	SD	Median	Min-Max			N^a	%^b
Kiruna	1	11	0.290	0.151	0.260	0.100	–	0.550	52,426	18.2%
Luleå	1	8	0.269	0.095	0.275	0.160	–	0.370	49,781	17.2%
Luleå	2	8	0.051	0.021	0.045	0.030	–	0.090	41,979	14.5%
Luleå	3	8	0.143	0.027	0.145	0.100	–	0.170	30,305	10.5%
Luleå	4	8	0.149	0.029	0.145	0.120	–	0.190	10,092	3.5%
Piteå	1	8	0.066	0.038	0.050	0.020	–	0.110	35,866	12.4%
Piteå	2	8	0.058	0.013	0.055	0.040	–	0.080	22,403	7.8%
Piteå	3	8	0.089	0.011	0.090	0.070	–	0.100	15,772	5.5%
Piteå	4	10	0.197	0.052	0.189	0.133	–	0.281	2529	0.9%
Other^c		77	0.152	0.110	0.120	0.020	–	0.550	27,658	9.6%

N Number of measurements at each swimming pool facility
^aThe total number of hours spent in indoor swimming pools until age 15 by children in the study
^bProportion of the total number of hours spent in indoor swimming pools until age 15 by children in the study
^cData for four “other” swimming pool facilities where no air concentration measurements were available are based on the 77 samples collected at the nine participating facilities with objective data

ISSN: 1476-069X