international standard for coronaviruses, dr. barak sees bsl 2 is too risky. >> we do all our work under bsl 3 conditions. we wear portable breathing apparatuses with tieback suits so workers are protected from anything that might be in the laboratory. >> now the wuhan institute virology is best known for its world class bsl 4 lab which became fully operational in 2018. those labs handle the world's most dangerous microbes with no known cures or treatments. >> this laboratory will mainly be used for research on highly pathogenic infectious diseases for which there are currently no medicine or vaccines. >> but in the year that it opened, u.s. diplomats visited the lab and expressed their concerns. >> they told their washington colleagues if a lab accident happened at this lab it could cause an outbreak of a bat coronavirus pandemic.