1. INTRODUCTION
Diffusive Samplings Evaluation and Optimization in Low Air Speed Workplaces
Williams ESTEVE*, Marianne GUILLEMOT, Eddy LANGLOIS
INRS, rue du Morvan, Vandoeuvre-lès-Nancy, France
Passive diffusion samplers are easy-to-use devices to assess exposure to organic vapors .
These passive samplers are recommended by manufacturers to be used with a minimum value of air speed (typically vmin = 0.1 m/s).
But, many workplaces are indoor and do not have important air movements (v < 0.1 m/s).
The objectives of this work were:
to evaluate the efficiency of the main diffusive samplers when v < vmin
to develop and validate a rotating rack in order to make reliable passive samplings in low air speed conditions.
Our job : making yours safer
Samplings of toluene, trichloroethylene and tetrachloroethylene during 8 hours at 1 ppm
RESULTS AND DISCUSSION
Samplings of toluene during 8 hours at 10 ppm
Representative of moderately polluted workplaces
Air speed > 0.1 m/s :
Low bias for the solvent desorption samplers (3M and GABIE).
Radiello samplers over-estimate the concentration of about 15% (wrong uptake rate).
Perkin Elmer badges give accurate results but with a significant variability between replicates.
Air speed < 0.1 m/s :
Decrease of the efficiency of the samplers, especially for 3M and GABIE.
With the rotating rack (see heavy lines dots) :
3M and GABIE samplers are about 10 to 15 % closer to the reference value.
MATERIAL & METHODS
TOLUENE
For air speeds v > 0.1 m/s , the results can be compared to those obtained for 8-hour samplings at 10 ppm.
A decrease of the efficiency of the samplers is observed when v < 0.1 m/s.
The accuracy of the measurements is improved with the rotating tool.
CHLORINATED ETHYLENES
The 3M and GABIE samplers give accurate results when v > 0.1 m/s. The Perkin Elmer badge significantly underestimates the concentration of TCE. The uptake rate provided for the PCE seems underestimated leading to overestimated results.
With no air speed (v  0), the efficiency of the samplers is improved with the use of the rotating tool, even for the Perkin Elmer tubes which are obviously not suitable in these conditions.
Passive samplers: 3M 3500, GABIE, Tenax Perkin Elmer and Radiello
Studied volatile organic compounds (VOCs): toluene, trichloroethylene (TCE), perchloroethylene (tetrachloroethylene, PCE).
Analyses performed by:
GC-FID (Varian 3400) with internal standards for the 3M and GABIE samplers after solvent extraction in CS2
ATD-GC-FID (Perkin Elmer TurboMatrix 350/Clarus 500) for Tenax tubes and Radiello badges with external calibration.
Samplings of toluene during 7 days at 1 ppm
Representative of low background contaminations
CONCLUSION
Field samplings
The experiments confirm that the accuracy of the passive samplings tends to decrease from 10 to 20 % when used in low air speed (< 0.1 m/s) and up to 50 % with no air speed.
Consequently, the concentrations obtained with passive samplers in workplaces with low air speeds must be considered carefully as they might underestimate the ambient contamination and the workers’ exposure.
The use of the rotating tool improves the their efficiency and provides similar results to those obtained with the recommended air speed (> 0.1 m/s).
Air speed > 0.1 m/s :
Concentrations obtained for the 3M, Gabie and Perkin Elmer samplers very close to the reference.
Poor efficiency of the Radiello sampler (bias of 50 % to the reference value) : not suitable in these sampling conditions due to back-diffusion.
Air speed < 0.1 m/s :
Decrease of the efficiency of the 3M and GABIE samplers.
With the rotating rack (see heavy lines dots) :
3M and GABIE samplers are about 15 % closer to the reference value.
Rotary rack used for passive samplings with low air speed
Gas test device regulating T, P, vair, [VOCs]
Acknowledgements
The authors would like to thank Laurence Robert, Nathalie Monta, Jennifer Klingler and Juliette Kunz-Iffli from INRS for field samplings and analyses.
*Contact :
(+33)

2. INTRODUCTION
Diffusive Samplings Evaluation and Optimization in Low Air Speed Workplaces
Williams ESTEVE*, Marianne GUILLEMOT, Eddy LANGLOIS
INRS, rue du Morvan, Vandoeuvre-lès-Nancy, France
Our job : making yours safer
RESULTS AND DISCUSSION
Samplings of toluene, trichloroethylene and tetrachloroethylene during 8 hours at 1 ppm
Samplings of toluene during 8 hours at 10 ppm
MATERIAL & METHODS
CONCLUSION
Samplings of toluene during 7 days at 1 ppm
*Contact :
(+33)