Wearing masks may diminish the rate of influenza transmission by reducing the amount of virus-containing droplet nuclei entering the surrounding area after leaving the mouth and nose of an infected subject. When worn by a non-infected subject in the presence of infected airborne droplets, surgical masks may reduce the amount of infected droplets inhaled and thereby reduce the chances of infection. However the degree to which a surgical mask can reduce airborne transmission is difficult to quantify given the lack of prior research in this area, and the expected benefit is uncertain. There are few apparent risks of wearing a mask, perhaps the greatest risk being that the mask engenders a feeling of overconfidence in the ability of the mask to prevent infection, leading to riskier activity (e.g. sitting closer to family members at mealtimes) than might have taken place if the mask were not worn, and thus an increased rather than decreased risk of influenza transmission.