It needs atleast 20 minutes a day in order to have an effective cardio exercise.
If you really wanted to have a good cardio exercise that will benefit you and have a good health and healthy lifestyle, then you have to spare your 20 minutes a day.
A carcinogen is defined as an agent (e.g. chemical) that can increase the risk of cancer.
Exposure to the carcinogens present in tobacco smoke increases the risk of developing cancer.
It causes lung cancer.
Hope this helps!