Which of the following is a limitation of using UV radiation for disinfection?

• A. UV radiation is highly effective against bacterial spores in all conditions.
• B. UV radiation increases the temperature of the environment significantly during use.
• C. UV radiation has poor penetration and is ineffective on surfaces that are not directly exposed.
• D. UV radiation leaves toxic chemical residues on treated surfaces.

Answer: (C)

Verified step by step guidance

1. Understand the nature of UV radiation as a disinfection method: UV radiation kills microorganisms primarily by damaging their DNA, preventing replication.
2. Recognize that UV radiation is effective only on surfaces that are directly exposed to the light because it has limited ability to penetrate materials such as glass, plastic, or organic matter.
3. Identify that UV radiation does not significantly increase the temperature of the environment, so heat-related effects are not a limitation.
4. Note that UV radiation does not leave any chemical residues since it is a physical method of disinfection, unlike chemical disinfectants.
5. Conclude that the main limitation of UV radiation is its poor penetration, making it ineffective on surfaces or areas that are shadowed or not directly exposed to the UV light.