title: Distribution and determinants of trihalomethane concentrations in indoor swimming pools.
abstract: OBJECTIVE
  For many decades chlorination has been used as a major disinfectant process for public drinking and swimming pool water in many countries. However, there has been rising concern over the possible link between disinfectant byproducts (DBPs) and adverse reproductive outcomes. The purpose of this study was to estimate the concentrations of trihalomethanes (THMs) in some indoor swimming pools in London and their variation within and between pools and any correlation with other factors.
  
  
  METHODS
  Water samples were collected from eight different indoor swimming pools in London. A total of 44 pool samples were collected and analysed for total organic content (TOC) and THMs. Water and air temperature were measured along with the pH during the collection of pool samples. The level of turbulence and the number of people in the pool at the time were also assessed.
  
  
  RESULTS
  The geometric mean concentration for all swimming pools of TOC was 5.8 mg/l, of total THMs (TTHMs) 132.4 microg/l, and for chloroform 113.3 microg/l. There was a clear positive linear correlation between the number of people in the swimming pool and concentrations of TTHMs and chloroform (r=0.7, p<0.01), and a good correlation between concentrations of TOC and TTHMs (r=0.5, p<0.05) and water temperature and concentrations of TTHMs (r=0.5, p<0.01). There was a larger variation in THMs within pools than between pools.
  
  
  CONCLUSIONS
  Relatively high concentrations of THMs were found in London's indoor swimming pools. The levels correlated with the number of people in the pool, water temperature, and TOC. The variation in concentrations of THMs was greater within pools than between pools.
authors.affiliation: Imperial College of Science, Technology and Medicine, Department of Environmental Science and Technology, Royal School of Mines, Prince Consort Road, London SW7 2BP, UK.
authors.forename: H
authors.initials: H
authors.lastname: Chu
authors.forename: M J
authors.initials: MJ
authors.lastname: Nieuwenhuijsen
mesh_terms: D000393:Air Pollutants / Q000032:analysis; D002725:Chloroform / Q000032:analysis; D004202:Disinfectants / Q000737:chemistry*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008131:London; D013551:Swimming Pools; D013696:Temperature; D022882:Trihalomethanes / Q000032:analysis*
chemical_list: D000393:Air Pollutants; D004202:Disinfectants; D022882:Trihalomethanes; D002725:Chloroform