Which BSL level indicates a need for protective equipment due to high-risk pathogens?

The correct answer is indicated by BSL-3. This biosafety level is defined by its need for specific protective equipment and stringent laboratory practices due to the presence of potentially lethal pathogens that can be transmitted through inhalation or contact. At this level, labs must implement controlled access, perform all work within biosafety cabinets, and use personal protective equipment such as gloves, masks, and face shields to protect personnel from exposure to infectious aerosols and other hazardous materials.

In contrast, BSL-1 is appropriate for work with well-characterized agents that are not known to consistently cause disease in healthy adults and requires minimal protective measures. BSL-2 involves pathogens that may cause moderate disease and requires some specific safety precautions but not to the extent of BSL-3. BSL-4 involves the highest risk pathogens, requiring the most stringent precautions and specialized facilities, but that speaks to an even greater level of containment than what is required at BSL-3.