1) A source of potential harm from past, current, or future exposures.
2) A situation that poses a level of threat to life, health, property, or environment. Most hazards are dormant or potential, with only a theoretical risk of harm; however, once a hazard becomes active, it can create an emergency situation. A hazard does not exist when it is happening. A hazardous situation that has come to pass is called an incident. Hazard and vulnerability interact together to create risk.