Evaluation of Membrane Filter Field Monitors for Microbiological Air Sampling

Abstract

Due to area constraints encountered in assembly and testing areas of spacecraft, the membrane filter field monitor (MF) and the National Aeronautics and Space Administration-accepted Reyniers slit air sampler were compared for recovery of airborne microbial contamination. The intramural air in a microbiological laboratory area and a clean room environment used for the assembly and testing of the Apollo spacecraft was studied. A significantly higher number of microorganisms was recovered by the Reyniers sampler. A high degree of consistency between the two sampling methods was shown by a regression analysis, with a correlation coefficient of 0.93. The MF samplers detected 79% of the concentration measured by the Reyniers slit samplers. The types of microorganisms identified from both sampling methods were similar. Variables in the MF samplers, such as pore size, relative humidity, and flow rates, have been studied, but no effect was noted on recovery. The results show that the MF method could be used to estimate the number and types of microorganisms found in the air.