Why is it hazardous?

Nitrate film is extremely flammable. It burns rapidly, intensely and produces toxic smoke. Nitrate fires are almost impossible to extinguish. Large fires are likely to be devastating to object collections and buildings.

In warm and humid conditions nitrate film will deteriorate faster. Deteriorating nitrate film may become more flammable in the early stages of decomposition but in final stages it may even lose its flammability. Deteriorating nitrate film releases harmful, acidic chemicals which will accelerate the deterioration of the film and cause corrosive damage to nearby materials.