title: Carbon monoxide exposure from cooking in snow caves at high altitude.
abstract: OBJECTIVE
  To determine the physiological consequences of acute CO exposure from cooking in snow caves at 3,200 m. We hypothesized that ambient CO and serum carboxyhemoglobin (COHb) levels would increase and that even low levels of COHb would be associated with symptoms of CO poisoning at high altitude.
  
  
  METHODS
  This was a prospective observational study. Twenty-two healthy volunteers age 18 years or older were recruited during a winter camping trip at 3,200 m. Subjects filled out symptom questionnaires, and heart rate (HR), oxygen saturation (SaO2), serum COHb, and ambient CO were all measured before and after cooking inside snow caves.
  
  
  RESULTS
  Median age of subjects was 32 years, and 87% were male. The median ambient CO level increased by 17 ppm (IQR, 2-27 ppm), P = .005. Mean serum COHb level rose from 0.3% (IQR, 0.2%-0.4%) to 1.2% (IQR, 0.7%-2.6%) after cooking, for a difference of 1% (IQR, 0.4%-2.3%), P < .001. There were no differences in symptom scores before and after cooking, and there was no significant effect on HR or SaO2.
  
  
  CONCLUSIONS
  A single exposure to CO at 3,200 m increases ambient CO and COHb but not to clinically important levels. Further studies are needed to examine the risks of longer exposures at higher altitudes.
authors.affiliation: Women's Health Research Center, University of Colorado Health Sciences Center, Denver, USA. Linda.Keyes@UCHSC.edu
authors.forename: L E
authors.initials: LE
authors.lastname: Keyes
authors.forename: R S
authors.initials: RS
authors.lastname: Hamilton
authors.forename: J S
authors.initials: JS
authors.lastname: Rose
mesh_terms: D000328:Adult; D016902:Air Pollution, Indoor / Q000009:adverse effects*; D000531:Altitude; D002248:Carbon Monoxide / Q000032:analysis*; D002249:Carbon Monoxide Poisoning / Q000097:blood* / Q000209:etiology; D002263:Carboxyhemoglobin / Q000378:metabolism*; D015331:Cohort Studies; D003296:Cooking; D004781:Environmental Exposure / Q000009:adverse effects*; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D011446:Prospective Studies; D011795:Surveys and Questionnaires
chemical_list: D002248:Carbon Monoxide; D002263:Carboxyhemoglobin