>>2911995"background radiation" is an offensively idiotic urban legend propagated by uneducated (basic physics, pls) cretins. I personally found and developed an undeveloped roll of film shot in ~'75 that spent the last 40 years in sawdust on a windy, uninsulated wooden attic, subjected to summer heatwaves and winter frost.
Apart from the fact it was shot on a shitty rapid system camera by a schoolboy, save for some uniform fogging, it was perfectly fine.