Abstinence from smoking and expired-air carbon monoxide levels: lactose intolerance as a possible source of error

Am J Public Health. 1990 Sep;80(9):1114-5. doi: 10.2105/ajph.80.9.1114.


We investigated a possible source of contamination of expired-air carbon monoxide (CO) readings on CO monitors from raised expired-air hydrogen (H2) levels, namely lactose intolerance, the norm in certain ethnic groups. A significant correlation between expired-air CO and H2 readings was observed in four non-smoking lactose maldigesters.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Breath Tests / standards*
  • Carbon Monoxide / analysis*
  • False Positive Reactions
  • Humans
  • Hydrogen / analysis
  • Lactose Intolerance / genetics
  • Lactose Intolerance / metabolism*
  • Racial Groups
  • Smoking* / genetics
  • Smoking* / metabolism


  • Carbon Monoxide
  • Hydrogen