Carbon monoxide is a poisonous gas that's released when smokers exhale. Nicotine is the chemical in cigarettes (and things of the like) that causes people to feel high.
Explanation:
Carbon monoxide (CO) releases is one of the deadly chemicals released into a smoker's bloodstream. Many people die from carbon monoxide poisoning. It's also in second-hand smoke. Nicotine can be used for medicinal purposes, but mostly is used as a stimulant drug. It can also cause buildup in the arteries and negatively affect the heart and people's hormones.
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