I have been following the discussions on the protection afforded by various types of masks. When I visited some MDR TB units in South Africa, I was given an N95 respirator which they promptly hung on a hook or placed in a desk drawer at the end of my visit. That struck me then as it does now that I was treated as a guest and provided with their safest equipment. I wondered how safe the masks are that are used repeatedly- some on a daily basis for a month. I observed nurses wearing surgical masks. The 2009 WHO policy on TB infection control in health care settings, congregate settings, and households (http://www.ghdonline.org/ic/resource/who-policy-on-tb-infection-control-in-he...) indicate they don't know, when "administrative and environmental controls are in place", the added value that particulate respirators provide beyond the safety of the surgical masks that are frequently used by hospital staff in resource-limited countries.
Do we know how safe surgical masks worn repeatedly are? It strikes me that if we don't have data on masks as used in practice, this is an area worthy of further investigation.
Thank you for your consideration.