Which surface should disinfectants generally not be used on?

• A. dirty, soft, porous surfaces
• B. clean non-porous surfaces
• C. metal surfaces
• D. glass surfaces

Answer: (A)

Disinfectants work best when they contact a clean, smooth, nonporous surface. Porous, soft materials—like wood, fabric, or other absorbent surfaces—can trap microbes in tiny crevices and soak up the disinfectant, preventing it from staying on the surface long enough to kill all pathogens. Dirt and organic matter on a surface can shield microbes and even neutralize some disinfectants, reducing their effectiveness. So, disinfectants are generally not reliable on dirty, soft, porous surfaces; clean those areas first and then apply disinfectant to nonporous, pre-cleaned surfaces such as metal or glass, following the product instructions.