title: Host and environmental predictors of exhaled breath temperature in the elderly.
abstract: BACKGROUND
  Exhaled breath temperature has been suggested as a new method to detect and monitor pathological processes in the respiratory system. The putative mechanism of this approach is based upon changes in the blood flow. So far potential factors that influence breath temperature have not been studied in the general population.
  
  
  METHODS
  The exhaled breath temperature was measured in 151 healthy non-smoking elderly (aged: 60-80 years) at room temperature with the X-halo device with an accuracy of 0.03°C. We related exhaled breath temperature by use of regression models with potential predictors including: host factors (sex, age) and environmental factors (BMI, physical activity, and traffic indicators).
  
  
  RESULTS
  Exhaled breath temperature was lower in women than in men and was inversely associated with age, physical activity. BMI and daily average ambient temperature were positively associated with exhaled breath temperature. Independent of the aforementioned covariates, exhaled breath temperature was significantly associated with several traffic indicators. Residential proximity to major road was inversely associated with exhaled breath temperature: doubling the distance to the nearest major intense road was observed a decrease of 0.17°C (95% CI: -0.33 to -0.01; p=0.036).
  
  
  CONCLUSIONS
  Exhaled breath temperature has been suggested as a noninvasive method for the evaluation of airway inflammation. We provide evidence that several factors known to be involved in proinflammatory conditions including BMI, physical activity and residential proximity to traffic affect exhaled breath temperature. In addition, we identified potential confounders that should be taken into account in clinical and epidemiological studies on exhaled breath temperature including sex, age, and ambient temperature.
authors.forename: Esmée
authors.initials: E
authors.lastname: Bijnens
authors.forename: Nicky
authors.initials: N
authors.lastname: Pieters
authors.forename: Harrie
authors.initials: H
authors.lastname: Dewitte
authors.forename: Bianca
authors.initials: B
authors.lastname: Cox
authors.forename: Bram G
authors.initials: BG
authors.lastname: Janssen
authors.forename: Nelly
authors.initials: N
authors.lastname: Saenen
authors.forename: Evi
authors.initials: E
authors.lastname: Dons
authors.forename: Maurice P
authors.initials: MP
authors.lastname: Zeegers
authors.forename: Luc
authors.initials: L
authors.lastname: Int Panis
authors.affiliation: Centre for Environmental Sciences, Hasselt University, Agoralaan Building D, Diepenbeek 3590, Belgium. tim.nawrot@uhasselt.be.
authors.forename: Tim S
authors.initials: TS
authors.lastname: Nawrot
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D015992:Body Mass Index; D001944:Breath Tests; D004779:Environment Design / Q000706:statistics & numerical data*; D045853:Exhalation / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology*; D018986:Motor Vehicles / Q000706:statistics & numerical data; D012044:Regression Analysis; D012111:Residence Characteristics / Q000706:statistics & numerical data*; D012737:Sex Factors; D013696:Temperature