hazardous

Hazardous is an adjective used to describe something that presents a danger or risk to health, safety, property, or the environment. In scientific, regulatory, and industrial contexts, objects or conditions may be designated as hazardous to indicate that special precautions are required.

Hazards are often categorized by type: chemical hazards (toxicity, flammability, corrosivity, reactivity); physical hazards (noise, heat, cold, radiation); biological hazards (pathogens); mechanical hazards (moving machinery); electrical hazards (shock); ergonomic hazards (repetitive strain). Some items may present multiple hazards.

Most jurisdictions regulate hazardous materials through labeling, safety data sheets (SDS), and hazard communication standards. Labels may include hazard statements and precautionary measures. Hazardous waste and transportation are governed by additional rules to ensure containment and proper disposal.

Managing hazardous situations typically follows a risk-informed approach: identify hazards, assess exposure and likelihood, implement controls (engineering controls, administrative measures, and personal protective equipment), and provide training and emergency response planning. Proper storage, segregation, ventilation, spill control, and waste disposal reduce risk.

The term is often contrasted with danger versus risk; hazard means the potential to cause harm, while risk combines that potential with the likelihood and severity of exposure. The word hazardous is used broadly across fields such as chemistry, manufacturing, healthcare, and environmental science.