Poor handling is the primary cause of deterioration for books, manuscripts, and ephemera; however, a poor environment can also be a cause of deterioration for books and paper.[32] Conservators must have knowledge of agents that cause decay in order to preserve items.[9] Agents of deterioration can include mishandling, light, fluctuating humidity, dust and pollution, fire, water, gas and heat, neglect, and pests and other vermin.[33] Inherent vice is "the quality of a material or an object to self-destruct or to be unusually difficult to maintain".[34] Paper, books, manuscripts, and ephemera are prime examples of materials subject to inherent vice.