McCoy, no smoking

"No smoking" sign visible

A "no smoking" sign was a notice placed in location where smoking was prohibited.

"No smoking" messages were found stenciled in the missile silo housing the Phoenix before its launch. (Star Trek: First Contact)

A "no smoking" sign was visible in the medical laboratory on Earth Two in 2266. (TOS: "Miri")

"No smoking" signage was also present on the Enterprise-class bridge simulator at Starfleet Academy. (Star Trek II: The Wrath of Khan)

In Star Trek II: The Wrath of Khan, director Nicholas Meyer had "No Smoking" signs posted on the bridge of the Enterprise. According to the text commentary for the film, at Gene Roddenberry's insistence, they were removed. Roddenberry felt that enlightened future Humans would not have hang-ups or addictions like smoking. The "No Smoking" sign can still be seen on the bridge in the opening "Kobayashi Maru" scene.