title: Influence of atmospheric nitric oxide concentration on the measurement of nitric oxide in exhaled air.
abstract: BACKGROUND
  Measurement of nitric oxide (NO) in exhaled air shows promise as a non-invasive method of detecting lung inflammation. However, variable concentrations of NO are measured in environmental air. The aim of this study was to verify a possible relationship between exhaled NO and atmospheric NO values during high atmospheric NO days.
  
  
  METHODS
  Exhaled air from 78 healthy non-smokers of mean age 35.3 years was examined for the presence of NO using a chemiluminescence NO analyser and NO levels were expressed as part per billion (ppb). The exhaled air from all the subjects was collected into a single bag and into two sequential bags. Before each test atmospheric NO was measured.
  
  
  RESULTS
  The mean (SE) concentration of exhaled NO collected into the single bag was 17.1 (0.6) ppb while the mean values of exhaled NO in bags 1 and 2 were 16.7 (1.3) ppb and 13.8 (1.2) ppb, respectively. The atmospheric NO concentrations registered before each test varied from 0.4 to 71 ppb. There was a significant correlation between exhaled NO in the single bag and atmospheric NO (r = 0.38, p = 0.001). The atmospheric NO concentration also correlated with exhaled NO both in bag 1 (r = 0.44, p = 0.0001) and in bag 2 (r = 0.42, p = 0.0001). These correlations disappeared with atmospheric NO concentrations lower than 35 ppb.
  
  
  CONCLUSIONS
  These results indicate a relationship between atmospheric NO and NO levels measured in exhaled air, therefore exhaled NO should not be measured on very high atmospheric NO days.
authors.affiliation: Istituto di Clinica delle Malattie dell'Apparato Respiratorio, Università di Parma, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Corradi
authors.forename: A
authors.initials: A
authors.lastname: Pelizzoni
authors.forename: M
authors.initials: M
authors.lastname: Majori
authors.forename: A
authors.initials: A
authors.lastname: Cuomo
authors.forename: E
authors.initials: E
authors.lastname: de' Munari
authors.forename: A
authors.initials: A
authors.lastname: Pesci
mesh_terms: D000328:Adult; D000393:Air Pollutants / Q000032:analysis*; D001944:Breath Tests; D005260:Female; D006801:Humans; D008163:Luminescent Measurements; D008297:Male; D008875:Middle Aged; D009569:Nitric Oxide / Q000032:analysis*; D018709:Statistics, Nonparametric
chemical_list: D000393:Air Pollutants; D009569:Nitric Oxide