Biosafety Level 4 is the highest level of biological safety and is used for work with dangerous and exotic agents that pose a high risk of life-threatening disease, which may be transmitted via aerosols and for which there is no available vaccine or treatment. In toxicology, BSL-4 is crucial for researching highly toxic substances and pathogens. Laboratories are isolated, with specialized ventilation and waste management systems. Personnel wear full-body, air-supplied, positive pressure suits while working.
