Table 5—

Risks of asthma, increased exhaled nitric oxide and of sensitisation to aeroallergens associated with the attendance at a residential outdoor chlorinated swimming pool before the age of 7 yrs during a cumulative time of>50 h

Residential outdoor pool attendance before the age of 7 yrsOR (95% CI)
NoYesUnadjustedp-valueAdjustedp-value
Subjects n80443
Any aeroallergen IgE#292 (36.4)23 (53.5)2.01 (1.08–3.72)0.032.20 (1.14–4.22)0.02
House dust mite IgE207 (25.9)18 (41.9)2.08 (1.11–3.88)0.022.42 (1.26–4.64)0.008
Cat IgE97 (12.1)10 (23.3)2.20 (1.05–4.61)0.042.57 (1.21–5.47)0.014
Dog IgE42 (5.2)2 (4.7)0.89 (0.21–3.78)0.871.13 (0.26–4.92)0.87
Mould IgE1 (2.3)23 (2.9)0.81 (0.11–6.1)0.841.09 (0.14–8.46)0.93
Pollen IgE169 (21.0)7 (16.3)0.73 (0.32–1.67)0.460.82 (0.35–1.89)0.63
Ever asthma77 (9.6)11 (25.6)3.25 (1.57–6.70)0.0013.49 (1.61–7.57)0.002
Current asthma+48 (6.0)7 (16.3)3.06 (1.30–7.24)0.012.98 (1.15–7.73)0.025
Exhaled NO>30 ppb§111 (13.8)12 (27.9)2.41 (1.20–4.84)0.012.67 (1.28–5.55)0.009
  • Data are presented as n (%), unless otherwise stated. OR: odds ratio; CI: confidence interval; Ig: immunoglobulin. The median pool attendance of the 43 adolescents having attended a residential pool before the age of seven was 300 hours (IQR, 148–480). #: ORs for sensitisation to aeroallergens were adjusted for total serum IgE, parental allergy and sex (house dust mite, any aeroallergen), total serum IgE and parental allergy (cat, dog) or for total serum IgE and sex (mould and pollen); : OR for ever asthma was adjusted for total serum IgE, parental asthma, sex, maternal smoking during pregnancy, house cleaning with bleach, mould on bedroom walls, number of older siblings and the attendance at nonresidential outdoor pool before the age of 7 yrs; +: OR for current asthma was adjusted for total serum IgE, parental asthma, sex, maternal smoking during pregnancy and house cleaning with bleach. §: OR for NO>30 ppb was adjusted for total serum IgE, parental allergy, sex and house cleaning with bleach.