What is the main idea of the text? is passive smoking harmful? You might think that smoking only harms smokers, but people who breathe second-hand smoke are also harmed. Second-hand smoke contains more than 250 toxic chemicals that can make people sick. More than 50 of these chemicals cause cancer in humans. Breathing in passive smoking even for a short time harms the cardiovascular system and increases the risk of heart attack. Each year in the U.S. passive smoking causes about 50,000 deaths among nonsmokers, including 3,400 deaths from lung cancer and 46,000 deaths from heart disease.
а) Passive smoking causes more death than first-hand smoking.
b) Second-hand smoke is as harmful as first-hand smoke
c) Each year passive smoking causes about 50000 deaths among nonsmokers in the world
d) Second-hand smoke contains more than 50 toxic chemicals​