Dangerous chemicals can cause serious and sometimes irreversible effects on human health when they are produced, stored, transported, used, or disposed of without proper control. In hazardous material management, understanding these health effects is essential for preventing occupational exposure, protecting emergency responders, and reducing risks to the surrounding community. The health effects of dangerous chemicals depend on their toxicity, concentration, duration of exposure, route of entry, and individual susceptibility. Chemicals may enter the human body through inhalation, ingestion, absorption through the skin or eyes, or injection through cuts and punctures. Inhalation is particularly dangerous because toxic gases, vapours, fumes, dusts, and aerosols can rapidly reach the lungs and bloodstream. Acute exposure produces effects that occur shortly after contact with a hazardous chemical. Irritation of the eyes, nose, throat, and skin is common. Some chemicals cause coughing, breathing difficulty, headache, dizziness, nausea, vomiting, or loss of consciousness. Highly toxic substances such as hydrogen sulphide, carbon monoxide, chlorine, and certain pesticides can interfere with oxygen transport or cellular respiration and may cause severe