There are calls for office workers to wear face masks to stop the spread of coronavirus.
A group of scientists think the possibility of airborne transmission is being underestimated by the World Health Organisation.
The WHO's acknowledged there's growing evidence that Covid 19 can be spread by tiny particles suspended in the air in crowded, indoor spaces.
Professor John Wenger from UCC is one of the more than 200 scientists who's signed the open letter.
He says better ventilation and more use of face masks in indoor settings would help stop the spread: