In order to create the atmospheric cold breath in the movie “The Exorcist”, the production refrigerated the bedroom set with four air conditioners and temperatures that would plunge to around 30 to 40 below zero.
It was so cold that perspiration would freeze on some of the cast and crew. This obviously negated the need for fake breath mist which is prevalent in many modern movies.
“The cold room in The Exorcist [where you could see my breath] was a set where for three months we filmed in the morning when it would be zero degrees.(…) So we didn’t really have “special effects” per se, like CGI breath coming out of my mouth. The room was genuinely cold and that was real breath coming out of my mouth. Billy Friedkin pushed the effects technicians to be the best that they could be. It was hard.” – Linda Blair