Tobacco smoking (including secondhand smoke) and short-term exposure to air pollution such as carbon monoxide, nitrogen dioxide, and sulfur dioxide (but not ozone) have been associated with MI. Other factors that increase the risk of MI and are associated with worse outcomes after an MI include lack of physical activity and psychosocial factors including low socioeconomic status, social isolation, and negative emotions. Shift work is also associated with a higher risk of MI. Acute and prolonged intake of high quantities of alcoholic drinks (3-4 or more) increase the risk of a heart attack.

How many cigarettes per day increase the risk of a heart attack?