In Conversation With Dr Randeep Guleria: All India Institute Of Medical Sciences (AIIMS) chief Dr Randeep Guleria said one N95 mask worn properly is good enough protection against Covid. However, two cloth masks or surgical masks are now recommended for better protection. Dr Guleria stressed that the mask must form a seal around the nose to be effective, adding that the bigger concern is Covid being airborne and therefore, ventilation is key.