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Evaluation of a tractor cab using real-time aerosol counting instrumentation.

Hall R; Heitbrink W; West N
American Industrial Hygiene Conference and Exposition, May 19-23, 1997, Dallas, Texas. Fairfax, VA: American Industrial Hygiene Association, 1997 May; :27
Aerosol instrumentation was used to evaluate air infiltration into tractor cabs that are used to protect the agricultural worker during pesticide applications. The laboratory and field tests were conducted on a John Deere 7000 series tractor cab equipped with high efficiency particulate air (HEPA) media. HEPA media was used to eliminate filtration efficiency considerations and to remove atmospheric condensation nuclei which was used as the test aerosol. Thus, the major source of aerosols was assumed to be leakage around filters and seals. Three particle counters were used to measure the concentration of ambient aerosols inside and outside of the enclosure over the range 0.01-15 microm. The ratio of the outside to inside measurements was used to calculate a protection factor. During the evaluations, two counters were placed ins ide the tractor cab (near the operator's breathing zone) and two were places outside (near the air intake). During our evaluations, the instruments were rotated to prevent instrument bias from affecting the findings The ratio of the two measurements was used to calculate how efficient the tractor cab was at removing aerosols. The results of the laboratory evaluation indicated that the enclosure was 99% efficient at removing aerosols between the range of 0.3-15 microm. During the field evaluation, the results indicated that the enclosure was 96-99% efficient at removing aerosols between the range of 0.3-6.5 microm. The cab was capable of providing an average protection factor of 38 (ratio of outside/ inside aerosol counts in the range of 0.1-1.0 microm) during the laboratory evaluation and 43 during the field evaluation. A particle counter was also used to identify any leak sources in the ventilation system. The test results in the ventilation system indicated that some small aerosols >1 pm) can penetrate the seals around the fresh air blower. The results from this study indicate that tractor cabs can be very effective at removing different size aerosols depending on the seals and filters used with the enclosure. This study has also demonstrated the practical use of real-time aerosol counting instrumentation to evaluate the effectiveness of enclosures and to help identify leak sources. The method used in this study can be applied to various cabs used in different industries including agriculture, construction, and manufacturing.
Aerosols; Air-filters; Air-quality; Tractors; Agriculture; Agricultural-workers; Agricultural-machinery; Agricultural-industry; Agricultural-chemicals; Pesticides; Laboratory-testing; Particulates; Particulate-dust; Filtration; Filters; Leak-prevention
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American Industrial Hygiene Conference and Exposition, May 19-23, 1997, Dallas, Texas
Page last reviewed: March 25, 2022
Content source: National Institute for Occupational Safety and Health Education and Information Division