A new assessment in the medical journal Lancet has found "consistent, strong evidence" that the SARS-CoV-2 virus, which causes COVID-19, is predominantly transmitted through the air. Therefore, public health measures that fail to treat the virus as predominantly airborne leave people unprotected and allow the virus to spread, according to six experts from the UK, USA and Canada, including Jose-Luis Jimenez, a chemist at the Cooperative Institute for Research in Environmental Sciences (CIRES) and the University of Colorado Boulder.