While it is still hotly debated, especially by the tobacco industry, second-hand smoke can be deadly. That 'side-stream smoke' comes off the burning end of the cigarette and burns at a lower temperature than when someone takes a drag. That cigarette is constantly putting those chemicals into the air for the five to 10 minutes the cigarette is lit.
Carbon monoxide decreases the body's ability to carry oxygen to tissues.
We will probably have evidence in 10 years that ETS causes the same in children. There are also plenty of statistics about other respiratory or lung ailments ETS causes. Additional episodes of increased severity in asthmatic children are worsened by environmental smoke, estimated to account for somewhere between 200,000 and 1 million cases per year. Don't sit in any restaurant where there is a nonsmoking section in the same room as a smoking section. It's just like trying to swim in the nonchlorinated section of the swimming pool.