Development of a method for measuring single-pass bioaerosol removal efficiencies of a room air cleaner

This paper presents the development of a method to measure single-pass micr obial particle reduction by a room air cleaner having a built-in blower, Th e method used a Collison nebulizer to generate bioaerosol challenge for inj ection into a 14 m(3)/min airflow duct. Bioaerosol samplers (impactors) wer e used to obtain upstream and downstream samples. The success of the method required ensuring the survivability and culturability of the organisms, th e selection of appropriate test organisms for this application, the impleme ntation of the necessary control tests, the development of good sampling pr otocols, and the use of nonbiological aerosol tests for comparisons and Qua lity Assurance/Quality Control (QA/QC) checks, A series of filtration efficiency tests was performed on only the filter el ements of the air cleaner. The tests were conducted with two Gram-positive bacteria, Bacillus subtilis and Staphylococcus epidermidis, and, for compar ison and QA/QC purposes, two nonbiological challenge aerosols, The biologic al data compared well with the nonbiological particulate test results, and both results were highly reproducible, Next, a series of filtration efficie ncy tests was performed on the entire air cleaner assembly using five diffe rent biological aerosols (two bacteria, two fungi, and a virus). For these tests the air cleaner was mounted in a test duct with the built-in fan oper ating and the flows balanced to simulate free-standing operation. The resul ts of these tests were also highly repeatable and correlated well with the nonbiological test results.