Smoking
Smoking was the act of inhaling and exhaling the smoke of tobacco from the end of a cigarette, pipe, or similar object.
The First Doctor occasionally smoked from a pipe. (TV: An Unearthly Child)
The Brigadier was conscious of the fact that smoking tobacco was a major cause of lung cancer, Tumours and cavities etc and as a result discouraged his subordinates from smoking. (PROSE: Doctor Who and the Green Death)
Aboard the SS Madame de Pompadour, smoking was done within smoking pods. (TV: The Girl in the Fireplace)
Tobacco was not the only substance that could be smoked. Another was cannabis. (PROSE: Kaleidoscope)
By the 21st century, locations such as London had "No Smoking" signs in certain areas, such as the basement of Henrik's. (TV: Rose)
Behind the scenes
The 2013 docudrama An Adventure in Space and Time opens with an actor portraying a Mondasian Cyberman smoking a cigarette on the set of The Tenth Planet.
According to NOTVALID: How The Monk Got His Habit, which is not accepted as a valid source for in-universe articles on this wiki, the fifth incarnation of the renegade Time Lord who would become the Monk spent some time in the 1970s and developed a smoking habit which caused his voice to become gravelly.