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Moldy interiors

May 14, 2014
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If a detailer knew the nature of the bacterium in the motor vehicles they work on they might have second thoughts about being in the business. Or, if they were knowledgeable about the affects and dangers of these germs they could be making a lot more money by more clearly explaining why customer should have their vehicles detailed regularly.

A study by Dr. Charles P. Gerba and Sheri L. Maxwell set out to test the presence of bacteria and mold in vehicles. It was quite possibly the most scientific test ever done on an automobile interior. There were 100 vehicles involved in the test in the states of Illinois, Arizona, Florida, California and Washington, D.C., to provide a good cross-section of climatic conditions across the country.

The following is a list of molds that were identified in the automobiles tested and the number of times they were isolated. Members of the genus Aspergillus (see sidebar) were the most common molds identified.

Genus of molds found
in vehicle interiors
No. of
Times ID
Aspergillus 37
Ulocladium 5
Alternaria 5
Penicillium 4
Geotrichum 2
Chrysosporium 2
Trichoderma 1
Aureobasidium 1
Geomyces 1
Chrysonilia 1

The isolation of molds was the highest in Chicago and the lowest in Florida. For example, the occurrence of molds was 15 times higher in Chicago than in Tampa. Florida also had the highest annual rainfall and mean annual average temperature. Thus, bacterial numbers are probably related to a combination of high humidity and temperatures.

The authors of the study referenced in this article have granted their permission to use the results of the project for this article. If you are interested in a copy of the results, please contact the author at

R.L. “Bud” Abraham is president of Detail Plus Car Appearance Systems, Portland, OR, and a nearly 40-year member of the car care industry. He is also a member of the Western Carwash Association Board of Directors.

Abraham can be contacted at

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