title: Model development and validation of personal exposure to volatile organic compound concentrations.
abstract: BACKGROUND
  Direct measurement of exposure to volatile organic compounds (VOCs) via personal monitoring is the most accurate exposure assessment method available. However, its wide-scale application to evaluating exposures at the population level is prohibitive in terms of both cost and time. Consequently, indirect measurements via a combination of microenvironment concentrations and personal activity diaries represent a potentially useful alternative.
  
  
  OBJECTIVE
  The aim of this study was to optimize a model of personal exposures (PEs) based on microenvironment concentrations and time/activity diaries and to compare modeled with measured exposures in an independent data set.
  
  
  METHODS
  VOC PEs and a range of microenvironment concentrations were collected with active samplers and sorbent tubes. Data were supplemented with information collected through questionnaires. Seven models were tested to predict PE to VOCs in 75% (n = 370) of the measured PE data set, whereas the other 25% (n = 120) was used for validation purposes.
  
  
  RESULTS
  The best model able to predict PE with independence of measurements was based upon stratified microenvironment concentrations, lifestyle factors, and individual-level activities. The proposed model accounts for 40-85% of the variance for individual VOCs and was validated for almost all VOCs, showing normalized mean bias and mean fractional bias below 25% and predicting 60% of the values within a factor of 2.
  
  
  CONCLUSIONS
  The models proposed identify the most important non-weather-related variables for VOC exposures; highlight the effect of personal activities, use of solvents, and exposure to environmental tobacco smoke on PE levels; and may assist in the development of specific models for other locations.
authors.affiliation: Division of Environmental Health and Risk Management, School of Geography, Earth, and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom.
authors.forename: Juana Mari
authors.initials: JM
authors.lastname: Delgado-Saborit
authors.forename: Noel J
authors.initials: NJ
authors.lastname: Aquilina
authors.forename: Claire
authors.initials: C
authors.lastname: Meddings
authors.forename: Stephen
authors.initials: S
authors.lastname: Baker
authors.forename: Roy M
authors.initials: RM
authors.lastname: Harrison
mesh_terms: D004781:Environmental Exposure; D004784:Environmental Monitoring / Q000379:methods*; D006801:Humans; D008962:Models, Theoretical; D055549:Volatile Organic Compounds / Q000032:analysis*
chemical_list: D055549:Volatile Organic Compounds