Secondhand smoke is more dangerous in enclosed spaces.

This statement is true in every way. Secondhand smoke is more dangerous than firsthand smoke. This is because there are no filters that are present in the air which makes the smoke directly enter the lungs unfiltered. Smokers have a lesser risk because of the filter attached to the cigarettes. These things are responsible for regulating the chemicals (e.g. nicotine, tar) that go inside the body which secondhand smokers don’t have. So if you are around smokers most of the time, you should start staying away because you might be getting more smoke inside your body than your friends who do smoke.

People who utilizes the progression principle will ensure their exercise program increases in frequency, intensity, time, and type. the changes need to happen gradually in order to ensure they make gains in their fitness program. a person who doesn't utilize the progression principle can still gain health benefits from exercising, but will not continue to improve in cardiovascular fitness.