The meaning of the word hazard can be confusing. Often dictionaries do not give specific definitions or combine it with the term "risk". For example, one dictionary defines hazard as "a danger or risk" which helps explain why many people use the terms interchangeably.
There are many definitions for hazard but the more common definition when talking about workplace health and safety is:
A hazard is any source of potential damage, harm or adverse health effects on something or someone under certain conditions at work.
Basically, a hazard can cause harm or adverse effects (to individuals as health effects or to organizations as property or equipment losses).
Sometimes a hazard is referred to as being the actual harm or the health effect it caused rather than the hazard. For example, the disease tuberculosis (TB) might be called a hazard by some but in general the TB-causing bacteria would be considered the "hazard" or "hazardous biological agent".
A common way to classify hazards is by category:
biological - bacteria, viruses, insects, plants, birds, animals, and humans, etc.,
chemical - depends on the physical, chemical and toxic properties of the chemical.
ergonomic - repetitive movements, improper set up of workstation, etc.,
physical - radiation, magnetic fields, pressure extremes (high pressure or vacuum), noise, etc,
psychosocial - stress, violence, etc.,
safety - slipping/tripping hazards, inappropriate machine guarding, equipment malfunctions or breakdowns