Are 'contact time' and 'dwell time' the same concept on disinfectant labels?

• A. No; they refer to different concepts.
• B. They are the same concept but refer to different products.
• C. Yes; both refer to the minimum time the surface must remain wet with the product for effective disinfection.
• D. No; dwell time is about temperature.

Answer: (C)

The idea being tested is that contact time and dwell time mean the same requirement on disinfectant labels: the surface must stay visibly wet with the product for a specified minimum period for disinfection to work. Microorganisms are killed as the product acts over that time, so removing the product or letting it dry too soon can prevent proper disinfection. Labels may use either term, and the numbers can vary by product, but the concept remains the same. Dwell time isn’t about temperature—the term specifically refers to how long the surface must stay wet for effectiveness (temperature can influence efficacy, but the clock for disinfection is the wet contact time).