Project: Detecting second hand smoke exposure in restaurants.
How can you test the hypothesis that non-smoking sections of restaurants are sometimes not smoke free?
Answer: a) through the sense of smell, b) through the use of sensitive detectors set up in smoking and non-smoking sections which can identify smoke and specific chemicals in tobacco smoke.

*19. Is smoking marijuana safer than smoking tobacco?

Marijuana smoke contains more carbon monoxide, more tar and more cancer causing chemicals than tobacco smoke. If the smoke from a marijuana cigarette and a tobacco cigarette (e.g., Marlboro) are blown forcefully through a clean tissue or handkerchief, it
can be demonstrated that the marijuana smoke contains even more tar than the tobacco smoke. (See Video Script pg 49) (slides v, w, x). This is the same tar that contains poisons that cause cancer, chronic bronchitis, emphysema and heart disease. Marijuana
smokers also inhale more deeply and hold it longer to get "high" thus exposing their lungs to more toxic chemicals. Smoking marijuana is not safer than smoking tobacco!

Chronic marijuana smokers have changes in their lung tissue that are similar to those that occur in chronic tobacco smokers. These changes can lead to bronchitis, emphysema and lung cancer. Regular smokers of 3-4 marijuana cigarettes per day experience similar amounts of cough, wheeze and sputum production and have similar histologic abnormalities as those who smoke approximately 20 tobacco cigarettes per day. Marijuana smoking results in decreased pulmonary function and decreased exercise tolerance and also harms the heart. It increases the heart rate by as much as 50% and reduces the supply of oxygen by very significantly raising blood carbon monoxide levels. Chronic marijuana use is associated with impairment of cognitive skills. In males it is associated with decreased serum testosterone levels, decreased sperm counts, decreased sperm motility, decreased libido, infertility, impotence and gynecomastia. Smoking marijuana can also have harmful effects on the unborn baby of a pregnant woman.

Short term effects of marijuana include a "high" feeling (euphoria) which lasts 3-4 hours as well as impairment in concentration, judgment and motor performance which last for 12-24 hours. Driving while under the influence of marijuana is as dangerous as driving while under the influence of alcohol and has been associated with an increased risk of fatal car accidents.