If used with hygiene measures like thorough hand washing and keeping a safe distance from others and still some people say any mask is better than none others however warned that masks give people a false sense of security for more I'm joined now by 3ply Masks Professor Ben cowling at the University of Hong Kong his research there focuses on respiratory virus transmission and the impact of control measures and prefer howling is also a co-director of the why-oh collaborating Center for infectious disease epidemiology and control at the H K U School of Public Health good to have you with us so please there are still a lot of math critics out there and there say that there's simply not enough evidence that wearing masks could actually stop or at least reduce.

The spread of the virus you however were involved in a study that was published just last week tell us a bit about that sure so the study that we did last week was a very careful experimental study in a laboratory of how much virus comes out of the Disposable Face Mask mouths of people with influenza or common cold infections including common core and virus and we found a lot of virus in the exhaled breath not only in the large droplets but also in the small particle aerosols and the second part of the study we looked at how well facemask blocked that virus from getting into the environment we captured all of the exhaled breath.

That these patients were breathing now and we found substantial reductions in the virus that was able to get into the environment when those patients wore surgical facemask including influenza and including human coronavirus well that sounds to me like the study says that we should wear face masks and perhaps it should even be mandatory what you say I think we need to be careful not to think that mask of a magic weapon against kovat we know the best things that we can do in the community is stay at home stay away from other people because that's what will definitely stop transmission but then if we do need to go out I think it might be better if people were wearing a mask than if they weren't but you mentioned at the beginning the supply limitations is one of the big challenges to that kind of policy all right just one more question about this discussion around whether or not we should wear face masks because it's also linked to fears that Asarco too could be airborne what do we know about that oh we don't know I think that jury's still out in the clip that you just played now you mentioned that face masks block the large droplets from coming out of someone who's infected but for the other person who's wearing them some of the air comes in the sides actually in both cases the air will come in the sides and leak but they can still protect against droplets what we found in asked was the actually surgical Mosca block many of the aerosol particles as well so even if Tsarskoe v2 is airborne a surgical mask could still provide some benefit obviously not as much as it .