Which ABSL level relates to infectious agents that cause serious or potentially lethal diseases when inhaled?

• A. ABSL-1 and higher
• B. ABSL-2 and higher
• C. ABSL-3 and higher
• D. ABSL-4 only

Answer: (C)

The key idea is that the level corresponds to how dangerous an inhalation-transmissible agent is and what containment is required to prevent aerosol exposure. When an agent can be inhaled and cause serious or potentially lethal disease, containment must be substantial enough to prevent airborne spread. That threshold begins at ABSL-3, which is designed for agents that can cause severe disease via inhalation and require negative-pressure environments, controlled access, specialized PPE, and procedures to minimize aerosol generation. Higher levels (ABSL-4) cover even more dangerous pathogens with the highest containment standards. Therefore, the appropriate choice is ABSL-3 and higher, since it applies to agents that pose serious or lethal inhalation risks, with ABSL-4 representing the most stringent end of containment.