title: 6.6-hour inhalation of ozone concentrations from 60 to 87 parts per billion in healthy humans.
abstract: BACKGROUND
  Identification of the minimal ozone (O(3)) concentration and/or dose that induces measurable lung function decrements in humans is considered in the risk assessment leading to establishing an appropriate National Ambient Air Quality Standard for O(3) that protects public health.
  
  
  OBJECTIVE
  To identify and/or predict the minimal mean O(3) concentration that produces a decrement in FEV(1) and symptoms in healthy individuals completing 6.6-hour exposure protocols.
  
  
  METHODS
  Pulmonary function and subjective symptoms were measured in 31 healthy adults (18-25 yr, male and female, nonsmokers) who completed five 6.6-hour chamber exposures: filtered air and four variable hourly patterns with mean O(3) concentrations of 60, 70, 80, and 87 parts per billion (ppb).
  
  
  RESULTS
  Compared with filtered air, statistically significant decrements in FEV(1) and increases in total subjective symptoms scores (P < 0.05) were measured after exposure to mean concentrations of 70, 80, and 87 ppb O(3). The mean percent change in FEV(1) (+/-standard error) at the end of each protocol was 0.80 +/- 0.90, -2.72 +/- 1.48, -5.34 +/- 1.42, -7.02 +/- 1.60, and -11.42 +/- 2.20% for exposure to filtered air and 60, 70, 80, and 87 ppb O(3), respectively.
  
  
  CONCLUSIONS
  Inhalation of 70 ppb O(3) for 6.6 hours, a concentration below the current 8-hour National Ambient Air Quality Standard of 75 ppb, is sufficient to induce statistically significant decrements in FEV(1) in healthy young adults.
authors.affiliation: Department of Anatomy, Physiology, and Cell Biology, University of California Davis School of Veterinary Medicine, Davis, California 95616, USA. esschelegle@ucdavis.edu
authors.forename: Edward S
authors.initials: ES
authors.lastname: Schelegle
authors.forename: Christopher A
authors.initials: CA
authors.lastname: Morales
authors.forename: William F
authors.initials: WF
authors.lastname: Walby
authors.forename: Susan
authors.initials: S
authors.lastname: Marion
authors.forename: Roblee P
authors.initials: RP
authors.lastname: Allen
mesh_terms: D000280:Administration, Inhalation; D000293:Adolescent; D000328:Adult; D004305:Dose-Response Relationship, Drug; D004781:Environmental Exposure / Q000009:adverse effects*; D005260:Female; D005541:Forced Expiratory Volume / Q000187:drug effects / Q000502:physiology; D006801:Humans; D008168:Lung / Q000187:drug effects* / Q000502:physiology; D008297:Male; D010083:Oxidants, Photochemical / Q000008:administration & dosage* / Q000009:adverse effects; D010126:Ozone / Q000008:administration & dosage* / Q000009:adverse effects; D012016:Reference Values; D014797:Vital Capacity / Q000187:drug effects / Q000502:physiology; D055815:Young Adult
chemical_list: D010083:Oxidants, Photochemical; D010126:Ozone