What chlorine concentration (ppm) is required to disinfect food contact surfaces and toys at emergency shelters?

• A. 100 ppm
• B. 200 ppm
• C. 50 ppm
• D. 400 ppm

Answer: (B)

Disinfecting surfaces that will contact food and toys in shelter settings requires a chlorine level strong enough to inactivate pathogens quickly, even when surfaces aren’t perfectly clean. The 200 parts per million free chlorine level provides a reliably effective kill for many bacteria and viruses on nonporous surfaces within a short contact time, which is important in crowded emergency shelters with varied soils and high turnover.

Lower concentrations, like 50 or 100 ppm, may not reliably disinfect when organic matter is present, increasing the risk of remaining pathogens. A much higher concentration, such as 400 ppm, can be unnecessarily harsh, more likely to cause corrosion and residue issues, and often isn’t needed if surfaces are properly pre-cleaned and given adequate contact time.

So, using 200 ppm strikes a balance between efficacy and practicality for preventing disease transmission through surfaces and toys, especially when you’ve pre-cleaned the area and allow the appropriate contact time for disinfection. Remember to prepare fresh solution daily, follow safety precautions, and rinse or air-dry as appropriate after disinfection.