Infectious aerosol characterization was reviewed and research needs relative to the application of engineering controls for the prevention of airborne infections in personnel in health care and other related facilities were identified and prioritized. This problem was addressed as a result of the reemergence of tuberculosis (TB) as a public health problem in the United States (US). A total of 26,000 active TB cases occurred in the US in 1991, representing a 2.3% increase over 1990 and an 18.4% increase over 1985. The sharp increase occurred primarily among the homeless, drug abusers, and those infected with the human immunodeficiency virus. All new cases of TB infection today are contracted by the aerosol route from infected patients who disperse infective droplet nuclei into the air when coughing. Health care and other related workers exposed to confined and TB prevalent populations have a high risk of infection, and are also at risk of contracting other infectious airborne diseases such as influenza, measles, chicken pox, psittacosis, Legionnaire's disease, and aspergillosis. Factors to consider when characterizing bioaerosols include source of generation, particle size, aerodynamic properties of the particles, infectivity and virulence, and viability as it relates to temperature and relative humidity. Most respiratory infections are transmitted through the air from human sources and result from inhalation of droplet nuclei. Infective bioaerosols can also be produced from environmental sources. Legionnaire's disease originating from exposure to aerosols generated from contaminated cooling towers was cited as an example of an opportunistic infection arising from an environmental source. The area of deposition within the respiratory tract is an important factor in determining the response to an inhaled infective bioaerosol. Deposition is also influenced by hygroscopicity. Inhaled aerosol particles increase in size as they move through the airways due to their taking up water. Environmental sampling and analysis of bioaerosols were considered.
Proceedings of the Workshop on Engineering Controls for Preventing Airborne Infections in Workers in Health Care and Related Facilities, July 14-16, 1993, Cincinnati, Ohio