Use of disposable face masks for public health protection against SARS.

The paper by Syed et al, 1 provides observations on the use of face masks by members of the public for protection against the severe acute respiratory syndrome (SARS) corona-virus (CoV). The authors' raise an important question as to whether masks are effective in preventing disease. The type of masks used can generally be categorised as either surgical or paper and are suggested to offer similar protection. For healthcare workers, it has been shown 2 that masks do not provide adequate protection against SARS CoV. However, protection for healthcare workers is somewhat different than that for those of the general public, especially those not directly exposed to droplet transmission on a ''continuous'' basis from an infected per-don. The finding of a possible dose-response 3 for exposure and infection to SARS CoV lessens the chance of infection through droplet transmission by the general public, especially when some personal protection is afforded. When masks are used along with other hygiene practices, risk of infection, excluding close contact with an infected person, like a family member, can be minimised. Masks have been shown to provide an increased protection rate of 2.4 for mycobac-terium tuberculosis in comparison with no mask. 4 As SARS CoV has been suggested to be spread by aerosol droplet and not to any significant degree by airborne transmission, 5 masks will probably provide some increased protection to the general public. However, as noted by Syed, it is necessary that they be properly used and changed frequently. As this virus can survive for 72 hours or more on surfaces, it is transmitted through fomite contact and infection can occur by mucus membranes (for example, conjunctiva) 5 ; thus, other personal hygiene practices (for example, hand washing) are of equal or greater importance. 4 For public health protection, use of masks can have some impact on preventing the spread of SARS CoV. However, this should be only one health practice that is encouraged by the public as others (for example, hand washing) are also of great importance. References 1 Syed Q, Sopwith W, Regan M, et al. Behind the mask. Journey through an epidemic: some observations of contrasting public health responses to SARS. intensive-care staff after brief exposure to severe acute respiratory syndrome. Tuberculosis in health care settings and the estimated benefits of engineering controls and respiratory protection. Public health guidance for community–level preparedness and response to severe acute LETTER If you …