The World Health Organization (WHO) and around 500 experts have agreed for the first time what it means for a disease to spread through the air, in a bid to avoid the confusion early in the COVID-19 pandemic that some scientists have said cost lives.

The Geneva-based U.N. health agency released a technical document on the topic on Thursday. It said it was the first step toward working out how to better prevent this kind of transmission, both for existing diseases like measles and for future pandemic threats.

The document concludes that the descriptor “through the air” can be used for infectious diseases where the main type of transmission involves the pathogen travelling through the air or being suspended in the air, in line with other terms such as “waterborne” diseases, which are understood across disciplines and by the public.