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Microbial Resistant Test Method Development
Citation:
Dean, T. AND D. Betancourt. Microbial Resistant Test Method Development. US Environmental Protection Agency, Cincinnati, OH, EPA/600/R-15/182, 2015.
Impact/Purpose:
The purpose of this research was to develop a standard test method to test multiple classes of building products for microbial resistance and product VOC off gassing. Upon completion of test method development the method was compared to currently used methods.
Description:
Because humans spend most of their time in the indoor environment, environmental analysis of the quality of indoor air has become an important research topic. A major component of the aerosol in the indoor environment consists of biological particles, called bioaerosols, and further breakdown of bioaerosols shows a major fraction to be fungal in origin. These fungal organisms have been shown to cause adverse health effects ranging from mild headaches to cases of idiopathic pulmonary hemosiderosis in infant children. To prevent fungal organisms from growing in the built environment many companies have developed and marketed microbial resistant building products. These companies have taken different strategies to produce microbial resistant products, including removing fungal growth substrates to adding antimicrobial chemicals into the final product. The aim of this study was to develop a quantitative antimicrobial testing method coupled to product volatile organic compound (VOC) offgassing analysis. This coupled microbial/chemical analysis is holistic and produces a true measure of the effectiveness of the product as well as information on VOC production. The developed test method was used to test three different classes of building materials for both microbial resistance and VOC offgassing. Important findings included extending the testing to 12 weeks allowed ubiquitous microbes to grow showing the importance of the comprehensive testing duration. Additionally quantitative analysis removed all uncertainty in determining the microbial resistance of a specific product. Upon completion of this test method development this project expanded further to evaluate currently utilized microbial (fungal) resistant testing methodologies as they are applied to gypsum products. Currently there are numerous methods that allow manufacturers to test for microbial resistance. Each of these methods is qualitative in nature allowing for results to be interpreted differently by various laboratories. Following a literature search five testing methods were identified and chosen to compare. We obtained detailed documents explaining the specific steps for completing the testing methods as they are meant to be utilized, and how the results are to be interpreted. Following our completion of these tests, the results show that the more stringent quantitative method removed all ambiguity from the analysis, as well as allowing for a more complete duration of testing lasting 12 weeks. While all of the tests are appropriate for their individual purposes, the quantitative test method developed and described herein works for a multitude of different microbial resistant products and product classes.