title: Relationship between carbon dioxide levels and reported headaches on the international space station.
abstract: OBJECTIVE
  Because of anecdotal reports of CO(2)-related symptoms onboard the International Space Station (ISS), the relationship between CO(2) and in-flight headaches was analyzed.
  
  
  METHODS
  Headache reports and CO(2) measurements were obtained, and arithmetic means and single-point maxima were determined for 24-hour and 7-day periods. Multiple imputation addressed missing data, and logistic regression modeled the relationship between CO(2), headache probability, and covariates.
  
  
  RESULTS
  CO(2) level, age at launch, time in-flight, and data source were significantly associated with headache. For each 1-mm Hg increase in CO(2), the odds of a crew member reporting a headache doubled. To keep the risk of headache below 1%, average 7-day CO(2) would need to be maintained below 2.5 mm Hg (current ISS range: 1 to 9 mm Hg).
  
  
  CONCLUSIONS
  Although headache incidence was not high, results suggest an increased susceptibility to physiological effects of CO(2) in-flight.
authors.affiliation: From the NASA Johnson Space Center (Dr Law, Ms Van Baalen, Dr Meyers, and Dr Alexander), Wyle Science, Technology and Engineering (Drs Foy and Wear), and MEI Technologies (Mrs Mason and Ms Mendez), Houston, Tex.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Law
authors.forename: Mary
authors.initials: M
authors.lastname: Van Baalen
authors.forename: Millennia
authors.initials: M
authors.lastname: Foy
authors.forename: Sara S
authors.initials: SS
authors.lastname: Mason
authors.forename: Claudia
authors.initials: C
authors.lastname: Mendez
authors.forename: Mary L
authors.initials: ML
authors.lastname: Wear
authors.forename: Valerie E
authors.initials: VE
authors.lastname: Meyers
authors.forename: David
authors.initials: D
authors.lastname: Alexander
mesh_terms: D000328:Adult; D016902:Air Pollution, Indoor / Q000009:adverse effects* / Q000032:analysis; D002245:Carbon Dioxide / Q000009:adverse effects* / Q000032:analysis; D005260:Female; D006261:Headache / Q000209:etiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D018531:Spacecraft
chemical_list: D002245:Carbon Dioxide