VPE 511: Environment and Environmental Hygiene (2+1)

PHYSICAL AGENTS

• Two important physical agents or heat and light
• Heat
  • Heat sterilization is an efficient and convenient procedure. Moist heat has the advantage of penetrating climps of organic matter and reaches surfaces not readily available to chemical disinfectants.
  • Dry heat requires higher temperatures and larger exposure periods than moist hat. Moist heat produces its germicidal effect by protein Coagulation, whereas dry heat oxidizes or -------------- microorganisms.
• Light
  • Ultraviolet light has antimicrobial activity. Ultraviolet wavelength of 254-280 nm are most effective against gram negative and non sporulating bacteria, while stephylocci and streptococci as well as viruses are resistant.