Exposure assessment of airborne microorganisms by fluorescence microscopy and image processing.

The purpose of this study was to improve the exposure assessment of airborne microorganisms by means of image processing of fluorescence microscopy images. This technique reduces the analysis time and also offers the opportunity to measure the size distribution of the microorganisms. We developed and implemented an automatic focusing procedure in order to count and size evaluate the microorganisms in the sample. However, automatic focusing was not possible if there were any impurities such as larger particles present. Therefore, manual focusing of the microscope had to be applied in connection with automatic counting and size evaluation when assessing the exposure of workers handling materials containing microorganisms, for example. This is also an improvement as it is faster than the fully manual standard methods. The new methods developed in this study correlated (r2 > 0.85) with the standard method for samples of E. coli and for samples of generated airborne bioaerosols from household waste, although a correction factor is necessary. No correlation was found for samples of generated bioaerosols from composted waste. This work has established a possibility for improving exposure assessment of airborne microorganisms by means of image processing instead of manual counting.

[1]  N O Breum,et al.  Sorting and recycling of domestic waste. Review of occupational health problems and their possible causes. , 1995, The Science of the total environment.

[2]  D. Vollath.  The influence of the scene parameters and of noise on the behaviour of automatic focusing algorithms , 1988 .

[3]  A. Nuttall,et al.  Three-dimensional analysis of contrast-filled microvessel diameters. , 1993, Microvascular research.

[4]  O. Lejeune,et al.  Automated image analyzing system for the quantitative study of living cells in culture , 1994, Microscopy research and technique.

[6]  T M Jovin,et al.  Fluorescence digital imaging microscopy in cell biology. , 1985, Science.

[7]  C. Odeyale,et al.  Computer Image Analysis Method for Rapid Quantitation of Macrophage Phagocytosis , 1990, Journal of leukocyte biology.

[8]  G Blomquist,et al.  Evaluation of methods for enumerating microorganisms in filter samples from highly contaminated occupational environments. , 1990, American Industrial Hygiene Association journal.

[9]  M. Sieracki,et al.  Measurement of marine picoplankton cell size by using a cooled, charge-coupled device camera with image-analyzed fluorescence microscopy , 1992, Applied and environmental microbiology.

[10]  S E Reichenbach,et al.  Evaluation of automated threshold selection methods for accurately sizing microscopic fluorescent cells by image analysis , 1989, Applied and environmental microbiology.

[11]  W. Eduard,et al.  Improvements in the quantification of airborne micro-organisms in the farm environment by epifluorescence microscopy , 1996 .

[12]  N O Breum,et al.  Collection of domestic waste. Review of occupational health problems and their possible causes. , 1995, The Science of the total environment.

[13]  L. C. Kenny,et al.  Automated focusing of an optical microscope , 1983 .

[14]  P. Malmberg,et al.  Collection of airborne micro-organisms on Nuclepore filters, estimation and analysis--CAMNEA method. , 1986, The Journal of applied bacteriology.