American Industrial Hygiene Conference and Exposition, May 19-23, 1997, Dallas, Texas. Fairfax, VA: American Industrial Hygiene Association, 1997 May; :11
In an aerosol chamber designed and built by NIOSH researchers, bioaerosols can be safely, uniformly generated, and easily sampled. The chamber is ducted through an auxiliary fan, into the main exhaust plenum for the laboratory and is always under negative pressure. To ensure the safety of laboratory personnel, and demonstrate the containment of bioaerosol within this chamber, a series of tests were performed. The supply and exhaust HEPA filters and gaskets were initially scanned and a leakage of less than 0.01 percent (NSF 49) was measured by a certified technician. To evaluate the integrity of the chamber construction (welds, connections, and access doors), a soap bubble test was performed. The HEPA filters were replaced with painted 1.9-cm (0.75-in) thick plywood blanks, and the chamber was pressurized to 500 Pa (2 in w.g.). After an initial failure, the gasket material was replaced and the chamber passed the bubble test, a series of bioaerosol experiments was performed. A mixed suspension of E. Coli and S. Marcescens was aerosolized under normal operating conditions, resulting in a total concentration of approximately 2,000 CFU/m3. The aerodynamic diameter of this aerosol was approximately 2pm. Andersen Six-stage bioaerosol samplers were used to collect bioaerosol inside the chamber and at each potential orifice (access doors, all gaskets, nebulizer opening, and chamber gasket). Subsequent tests were performed with a higher challenge bioaerosol concentration (20,000 CFU/m3). Tests were performed at a flow rate of 11.3 m3/min (400 cfm) and at zero flow. No E. coli or S. Marcescens CFUs were collected outside of the chamber under any of the three conditions. All penetrations into the chamber must be carefully checked prior to each use (e.g. proper sealing of all gaskets). In conclusion, following an evaluation protocol such as this will ensure the laboratory personnel of the integrity of the bioaerosol chamber when potentially infectious microorganisms are aerosolized.
American Industrial Hygiene Conference and Exposition, May 19-23, 1997, Dallas, Texas