What is the ruling in regards to smoking cigarettes?

Smoking is categorized as Makrooh-e-Tahreemi and therefore impermissible.

If the contents or ingredients used in the Hooka flavoring is Halaal, then the flavouring will be considered Halaal, but the actual smoking of the “hubbly-bubbly”is also categorized as Makrooh. However, if it consists of any intoxicating ingredients, then it will be Haraam. Re:- Fataawa Darul Uloom Zakariyya Pg. 674 Vol.6

According to Wikipedia, E–cigarette users who use devices that contain nicotine, are exposed to its potentially harmful effects. Nicotine is associated with cardiovascular disease, possible birth defects, and poisoning. … E–cigarette vapor potentially contains harmful chemicals not found in tobacco smoke.

Based on the above information, e-cigarettes seem to be as harmful as cigarettes, hence, the same ruling as explained in #1 will be attached to it, if it doesn’t contain any Haraam ingredients. Vape follows the very same concept of e-cigarettes, hence, the same ruling will be applicable to both.