There may be spoiled food in the cafeteria freezers, chill box, and pantry. Also, vending machine food may be spoiled or contaminated. There may be sewage backup through floor drains, sinks, and toilets. Sewage-line breaks may create pools of raw sewage on the ground. Standing water may breed a host of insects.
Animal carcasses provide food for and ruble provides shelter for rodents and other pests.
Security Hazardss Fencing may be down due to falling trees or shifting ground. There may be looting and vandalism. Sensitive records and objects may be out of place, exposed, or lost.