Ventilation Control of Indoor Transmission of Airborne Diseases in an Urban Community

Following the recent severe acute respiratory syndrome epidemics and worldwide concern about the next pandemic, whether influenza or multiple drug resistant tuberculosis, has underlined the importance of effective interventions into airborne disease transmission in indoor environments in a community. The engineering control measures available include ventilation dilution, use of high-efficiency particulate air filters in a room or in the heating, ventilation, and air-conditioning (HVAC) system, and use of ultraviolet germicidal irradiation devices in ceiling area of a room or in the HVAC system. These methods are known to be effective in controlling or delaying airborne disease transmission in a single enclosure in both healthcare facilities and the community. However, there have been no studies of their relative effectiveness at the community level. This paper presents mathematical modeling of some engineering control strategies with a focus on ventilation and corresponding analysis of their relative effectiveness compared with other public health interventions in disease control in indoor environments at the community level. The results should help us to determine the most effective intervention strategies. We conclude that the engineering intervention methods such as building ventilation can be as effective as public health interventions and the ventilation rates specified in the existing standards such as ASHRAE 62 may be too low for the purpose of preventing or controlling airborne infectious diseases in indoor environments.