In with the good air

The almost continuous reconstruction of healthcare facilities challenges the safety of patients because of the continual occupancy of hospitals. Traditional safety measures during construction have focused on avoiding hazards such as fire, mineral dust, and chemical aerosols. Since the development of transplant technology and other immunosuppressive therapies, opportunistic pathogens have become more frequent nosocomial pathogens. Immunocompromised patients are often devastated by infections, which can result in death. The removal of existing buildings to make way for new healthcare facilities and the renovation of existing buildings can result in aerosolization of such pathogens. In this issue of Infection Control and Hospital Epidemiology, Srinivasan et al.1 describe the generation of a tremendous dust cloud caused by explosive demolition. Their article provides data verifying that safety measures worked during a massive potential exposure to airborne contaminants. Before this demolition project, Thio et al.2 had described an outbreak of aspergillosis due to deficiencies in building ventilation systems at the same institution. Correcting these deficiencies was paramount to ensuring air quality during this subsequent demolition. In 1983, Streifel et al.3 described an explosive demolition at the University of Minnesota in preparation for renewal of the old hospital. The 1983 protective measures involved ventilation manipulation and building protection for areas housing immunocompromised patients. Srinivasan et al. used ventilation management methods that required continuous operation of ventilation systems so as to ensure building pressure. Except for smoke management, the importance of building depressurization was relatively unknown in 1983. Building depressurization seems to be an undiscovered problem in healthcare facilities and is dependent on continuous air balance considerations for mechanical ventilation. For example, it is easier to add exhaust systems to a building than to increase the supply air. This fact has contributed to the tendency of buildings to become depressurized, making it easier for unfiltered air to enter. Since 1947, hospitals have been required to meet ventilation standards set forth in the Hill Burton Act, which distributed funds to assist in the construction of hospitals. Since then, the ventilation parameters have been developed to provide guidance to enhance the comfort and safety of the occupants of healthcare facilities. Currently, the American Institute of Architects (AIA) provides the design guidelines for construction in healthcare facilities.4 These guidelines address filter efficiency, air exchanges, and pressure management as factors necessary for the control of air quality. They are used by more than 40 states in developing design criteria for construction projects. Since 1996, the construction section of these guidelines has required the incorporation of features that facilitate infection control. Prior to 1996, construction management and design concerns were largely associated with controlling odors and mineral dust and engineering design concepts were associated with temperature and humidity control. The guidelines for construction in healthcare facilities provide a focus on the construction and ventilation management specifications for general and specific hospital mechanical systems. In another article in this issue of Infection Control and Hospital Epidemiology, Hahn et al.5 describe the addition of high-efficiency particulate air (HEPA) filters for preventing aspergillosis. Although HEPA filters are important, their installation is relatively complex and requires extensive engineering design for appropriate control of fungal spores. To install HEPA filters, it is necessary to increase fan size to drive the increase in static pressure due to an increase in filter efficiency. For example, in the outbreak described by Thio et al., the healthcare facility had been using HEPA filters, but the lack of building pressurization circumvented their value by allowing unfiltered air to enter the building through pathways other than the intakes of the air handling system.2 Therefore, it would be prudent for a protective environment (PE) to be pressurized in order to prevent the infiltration of unwanted airborne particles into susceptible patient care areas. The AIA has identified special ventilation (SPV) areas requiring specific pressurization, air exchanges, and filtration for infection control as special ventilation rooms, including airborne infection iso-