There are deadly diseases on campus; they live in a few of the hundreds of labs. Scientists at UT-Austin take the strictest precautions to ensure these pathogens do not reach students. These precautions are organized into levels labs must comply with: biosafety level (BSL) 1, 2, 3 and 4. The highest biosafety level at UT-Austin is BSL-3. BSL-3-level defenses are used for pathogens that could be deadly if inhaled. There are no BSL-4 labs on campus, but scientists at UT-Austin sometimes use data that scientists at UTMB gather for further research. There are only 15 BSL-4 labs in the world, and the UTMB branch has two. According to the UTMB website, scientists there study pathogens that cause illnesses such as anthrax, hemorrhagic fevers and drug-resistant tuberculosis.