Some studies link smoking with miscarriage and stillbirths. Some research also suggests that smoking when pregnant can lead to the child having learning and behaviour problems. Sidestream or secondhand smoke that is not directly inhaled by the smoker can harm people who are exposed to it. Tolerance and Dependence Tolerance is the body adapting to the presence of a drug. When tolerance to a drug increases, more of the drug is necessary to achieve the same effect.
Smokers develop tolerance to the effects of tobacco.
Almost everyone who smokes develops a dependence on tobacco that is very difficult to break. Withdrawal symptoms can include irritability, anxiety, sleep and appetite disturbances, changes in temperature and heart rate, and a strong craving for tobacco. The popularity of cigarette smoking is at an all-time low in Canada. Almost 70 percent of Canadians are non-smokers. In recognition of the dangers of sidestream smoke, many public places have been declared smoke free.