Kk. Foarde et al., Development of a method for measuring single-pass bioaerosol removal efficiencies of a room air cleaner, AEROS SCI T, 30(2), 1999, pp. 223-234
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.