COSHH is UK law requiring employers to control substances hazardous to health. It involves identifying health hazards, conducting risk assessments, implementing control measures like PPE, providing training, monitoring health, and planning for emergencies. Hazardous substances include chemicals, fumes, dusts and vapors. Employers must prevent exposure, maintain control measures, provide instruction and training, and conduct health surveillance. Employees must follow safety procedures, wear PPE, report issues, and attend medical check-ups. When working with blood and tissues, universal precautions like gloves, safety glasses and sharps containers help prevent transmission of pathogens like hepatitis B and HIV.