The second priority is environmental control methods that are used to reduce the concentration of droplet nuclei in the air in high-risk areas. Environmental control methods range from inexpensive methods such as maximising natural ventilation and mechanical ventilation, to more costly methods such as ultraviolet germicidal irradiation and HEPAfiltration. Environmental control methods should not be used in absence of, or as a replacement for, administrative control measures. The third priority is to protect HCWs, via personal respiratory protection, from inhaling infectious droplets. Surgical masks prevent the spread of microorganisms from the wearer but do not provide protection to the wearer.
Respirators provide protection to the wearer from inhaling infectious droplet nuclei.
Respirators are expensive and they should be reserved for high-risk referral hospital settings. Efforts should be made to execute such control strategies to prevent nosocomial transmission of M. tuberculosi s. Such measures serve not only to conserve resources in terms of direct costs due to treatment of HCWs and indirect costs in terms of loss of HCWs specialising in the management of TB patients, but also in reducing the burden due to tuberculosis.