Does a UV light kill salmonella better below or above?

UV light is generally more effective at killing Salmonella when it is above the surface, as it can penetrate directly and disinfect the area more efficiently. However, UV light must be able to reach the microorganisms; if they are in crevices or covered by other materials, the effectiveness decreases. Therefore, ensuring direct exposure to UV light is crucial for maximum efficacy against Salmonella.