The Motion Picture Association of America's (MPAA) ratings board is getting tough on smoking in film.

Until now the ratings board has regarded sex, violence, adult language and illegal smoking among teens as the elements most likely to incur its wrath.

However, an edict delivered today stressed than all depiction of smoking that glamourises the act, or films that contain pervasive smoking outside 'an historic or other mitigating context', may warrant a harsher certification.

'Clearly, smoking is increasingly an unacceptable behaviour in our society,' MPAA chairman and chief executive officer Dan Glickman said. 'This action is an extension of our current practice of factoring under-age smoking into the rating of films. Now, all smoking will be a consideration in the rating process.'

'Three questions will have particular weight for our rating board when considering smoking in a film: Is the smoking pervasive' Does the film glamourise smoking' And, is there an historic or other mitigating context' Additionally, when a film's rating is affected by the depiction of smoking, that rating will now include phrases such as 'glamourised smoking' or 'pervasive smoking.' '

Glickman added that from July 2004 to July 2006 the percentage of films that included 'even a fleeting glimpse' of smoking dropped from 60% to 52%. Of those films, 75% received an R rating for other factors.