All tobacco products are harmful, no matter whether one is taking bidis, cigarettes, cigars, pipes, dokta, zarda, khaini, or snuff. Tobacco causes cancer, heart disease, brain stroke, respiratory disease, and so on. There can be no valid excuse for taking tobacco. Tobacco products are harmful even if the subject claims not to inhale the cigarette smoke, or spits out immediately after chewing khaini, dokta, or zarda. Even passively inhaled tobacco smoke is harmful. So, when someone smokes while sitting next to you, please ask them to move away. Alternatively, you should move far away from them.
If the subject requires tobacco before going to the wash room, they should quit the tobacco and take a fecal softener instead.
There can be no logic in giving up tobacco products gradually. People who plan to give up tobacco gradually will continue to take them for many months and years, and never stop completely. This is just an excuse to continue to take tobacco.