The environment in the context of cultural heritage includes the microbiology of the environment, radiation, temperature, relative humidity and contaminants.

Relative humidity controls the rate of chemical decay and influences the physical state of materials. RH also controls most types of biological decay.

Temperature controls the rate of chemical decay, and influences the physical state of materials.

Contamination by air pollution affects metal corrosion, complex salt formation in calcarious materials and the hydrolysis and oxidation of organic materials for example in leather, paper, plastics, or colourants.  Light and radiation cause materials to fade and enbittle.

The combination of all these factors puts cultural heritage at risk.