What is a common negative effect of high humidity on film storage?

High humidity can lead to film fogging, which is a common issue in film storage. When film is exposed to high moisture levels, it can absorb excess humidity, causing chemical reactions within the film emulsion. This results in a reduction of the film's ability to produce clear images, as fogging creates a hazy appearance that obscures detail. The embedded silver halide crystals within the film can undergo changes due to moisture, leading to unintentional exposure or a decrease in image quality. Maintaining appropriate humidity levels is essential for proper film preservation and ensuring that images remain sharp and free from unwanted artifacts.