Smoking among teenagers is one of the most pressing health issues. When a person smokes, their body intakes several toxic gases and chemicals including carbon monoxide, sulfur dioxide, hydrogen sulfide, formic acid, cyanhydric acid, acetic acid, nicotine, ammonia, arsenic, and lead. Smoking can cause diseases of the respiratory tract, change the color of teeth, shorten one's life by 1-4 years, cause vasoconstriction, deteriorate activity levels, lead to financial hardship, and increase the risk of drug addiction. A survey found that smoking rates increased with age for both boys and girls in grades 6-11.