The common meaning of risk is simply the likelihood of something bad happening. But when scientists talk about risk, the definition becomes more specific. They define risk as the probability of suffering injury, disease, death, or other loss as a result of exposure to a hazard. A hazard is something that can cause injury, disease, death, loss of property, or destruction of the environment. Simply put, a hazard is a threat to something people value and risk is a measure of the chance that a hazard will cause harm or loss.
Risk is an unavoidable and sometimes exciting part of life.
We are all exposed to hazards and their risks everyday. Some risks are involuntary. Being struck by lightning and being exposed to the potential hazards in the air and water are largely beyond our control. Other risks are voluntary. Many people choose to smoke cigarettes, ski, and drive even though these activities can be hazardous.