Experiment Mimics 'Extreme' Exposure to Secondhand Cannabis Smoke (image) Johns Hopkins Medicine Share Print E-Mail Caption Non-smoking volunteers are exposed to cannabis smokers' secondhand smoke for one hour in an experimental chamber at Johns Hopkins. When ventilation fans were turned off, as in this image, all non-smokers showed detectable levels of cannabis' active ingredient in blood and urine, and reported feeling effects of the drug. Credit Courtesy of Johns Hopkins Medicine. Usage Restrictions None. Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.