JIM VARNEY / SCIENCE PHOTO LIBRARY JIM VARNEY / SCIENCE PHOTO LIBRARY
Smoking cessation test. Teenage girl exhaling into a carbon monoxide breath monitor. Smokers have higher concentrations of poisonous carbon monoxide gas in their lungs than non-smokers. The monitor is a good means of providing positive feedback to quitters as they can see the concentrations of carbon monoxide decrease, showing their progress.
Model release available. Property release not required.