The answer to the questions is: Yes, they do protect people. This is the evidence:
Several studies have found a significant decline in cotinine which is an alkaloid found in tobacco. The decrease was found in both hospitality workers and the general public. For example, since the prohibition of smoking in New York state in 2003 in all indoor areas of workplaces, cotinine in nonsmoking adults decreased by 47.4%. Therefore, we can state that after implementing the law the harm done by secondhand smoke has been dramatically reduced. Studies like this have also been conducted in places like Ireland an England.
