There is a direct correlation between the amount of time a film is handled and how long it lasts. Every time you project a film there is an increased risk that the film will suffer physical damage from the projector. If you wish your film to last for its maximum life, it would ideally not be used at all. However, this defeats the purpose of having the material. One approach which is used in archives throughout the world is to have copies of the film made (video is very convenient) and to play these copies rather than the originals. In this manner the film can be both seen and kept in storage.
The life of films, no matter what the format or type, primarily depends upon the temperature and the humidity at which the film is stored. There are nitrate films 100 years old which are in good condition and ’safety’ films showing signs of deterioration after 10 years.
There has been a great deal said in the past about the impermanence of cellulose nitrate films due to their flammable properties. However, it is becoming increasingly obvious that `safety’ films will also deteriorate rapidly, although they will not burn so readily.