Infectious blood spills should be cleaned using a _____ dilution (1 part household bleach to 9 parts water).

The correct answer is derived from the standard practices for cleaning up infectious materials, particularly blood spills. A 10% dilution of household bleach to water is recommended because bleach is a powerful disinfectant effective against a wide range of pathogens, including bloodborne viruses like HIV and Hepatitis B and C.

When cleaning up infectious blood spills, the 10% bleach solution effectively kills these pathogens, making the environment safer for anyone who may come into contact with the area. Using this proper concentration ensures a balance between effective disinfection and safety, as higher concentrations could potentially damage surfaces or create hazardous fumes while offering only marginally increased efficacy.

Other dilutions are either too weak to ensure proper disinfection or not commonly recommended for such purposes. For example, a 5% dilution might not sufficiently neutralize the pathogens present in the blood, making it a less effective choice. A 25% or 50% dilution would be overly strong, potentially damaging surfaces and posing health risks without significant additional benefits over a 10% solution. Thus, a 10% bleach solution is the most widely accepted and practical choice for disinfecting blood spills.