Which statement best describes the effect of bleach concentration on disinfection?

Which statement best describes the effect of bleach concentration on disinfection?

• A. Higher concentration is always better
• B. Concentration does not affect effectiveness
• C. More is not always better
• D. Bleach is ineffective

Answer: (C)

More is not always better. Bleach works best within a recommended concentration range. Pushing the concentration higher than that range doesn’t significantly improve disinfection and can actually cause problems: it can be harsh on surfaces and materials, irritate skin and eyes, and create hazardous fumes. In addition, the presence of organic matter (dirt, feces, blood) can consume the active chlorine, making disinfection less effective regardless of how strong the solution is. Cleaning first, using the correct dilution, and allowing the surface to stay wet for the required contact time are what really drive effective disinfection.

More is not always better. Bleach works best within a recommended concentration range. Pushing the concentration higher than that range doesn’t significantly improve disinfection and can actually cause problems: it can be harsh on surfaces and materials, irritate skin and eyes, and create hazardous fumes. In addition, the presence of organic matter (dirt, feces, blood) can consume the active chlorine, making disinfection less effective regardless of how strong the solution is. Cleaning first, using the correct dilution, and allowing the surface to stay wet for the required contact time are what really drive effective disinfection.