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Aerodynamics and Exposure Variability.

PB91197517

Publication Date	1990
Personal Author	Flynn, M. R.; George, D. K.
Page Count	14
Abstract	Exposure levels and how orientation of the body with respect to air flow direction affect mean exposure were investigated in wind tunnel studies with a mannequin and sulfur-hexafluoride as a tracer gas. The mannequin was 41 inches high, and air velocities of 49, 152 and 265 feet per minute were used. Using a point source of tracer gas indicated that locating a contaminant source within a separated boundary layer results in greater exposure variability than when the source is outside such a region. These results provide information for estimating the relative exposure variability between processes under different aerodynamic conditions. While these findings focus on worker position as the generator of such a separated region, such examples will occur in any instance where there is relative motion between the air and a bluff body. Work occurring in large recirculating eddies formed by air movement around machines, or internal walls and boundaries will likely result in greater exposure variability when the pollutant source is within such a zone. The number of measurements needed to evaluate exposure is likely to be greater for such situations. This should serve as a crude guide to help industrial hygienists identify situations of high exposure variability on a relative basis.
Keywords	Occupational exposure Variability Air flow Aerodynamics Industrial hygiene Simulation Wind tunnels Air pollution Air pollution control Ventilation Sulfur hexafluoride Mannequins Work environments Tracer gas
Source Agency	National Institute for Occupational Safety and Health
NTIS Subject Category	68A - Air Pollution & Control 94D - Job Environment 41I - Job Environment 51A - Aerodynamics
Corporate Authors	North Carolina Univ. at Chapel Hill. Dept. of Environmental Sciences and Engineering.; National Inst. for Occupational Safety and Health, Cincinnati, OH.
Supplemental Notes	Sponsored by National Inst. for Occupational Safety and Health, Cincinnati, OH.
Document Type	Technical Report
NTIS Issue Number	199117

Aerodynamics and Exposure Variability.

Aerodynamics and Exposure Variability.
PB91197517

Publication Date	1990
Personal Author	Flynn, M. R.; George, D. K.
Page Count	14
Abstract	Exposure levels and how orientation of the body with respect to air flow direction affect mean exposure were investigated in wind tunnel studies with a mannequin and sulfur-hexafluoride as a tracer gas. The mannequin was 41 inches high, and air velocities of 49, 152 and 265 feet per minute were used. Using a point source of tracer gas indicated that locating a contaminant source within a separated boundary layer results in greater exposure variability than when the source is outside such a region. These results provide information for estimating the relative exposure variability between processes under different aerodynamic conditions. While these findings focus on worker position as the generator of such a separated region, such examples will occur in any instance where there is relative motion between the air and a bluff body. Work occurring in large recirculating eddies formed by air movement around machines, or internal walls and boundaries will likely result in greater exposure variability when the pollutant source is within such a zone. The number of measurements needed to evaluate exposure is likely to be greater for such situations. This should serve as a crude guide to help industrial hygienists identify situations of high exposure variability on a relative basis.
Keywords	Occupational exposure Variability Air flow Aerodynamics Industrial hygiene Simulation Wind tunnels Air pollution Air pollution control Ventilation Sulfur hexafluoride Mannequins Work environments Tracer gas
Source Agency	National Institute for Occupational Safety and Health
NTIS Subject Category	68A - Air Pollution & Control 94D - Job Environment 41I - Job Environment 51A - Aerodynamics
Corporate Authors	North Carolina Univ. at Chapel Hill. Dept. of Environmental Sciences and Engineering.; National Inst. for Occupational Safety and Health, Cincinnati, OH.
Supplemental Notes	Sponsored by National Inst. for Occupational Safety and Health, Cincinnati, OH.
Document Type	Technical Report
NTIS Issue Number	199117