Comparative evaluation of stationary and personal samplers for workplaces, preliminary study.
S. Grinshpun, O. Witschger, S. Fauvel, Colloque International "Poussières"2001, du 11 au 13 juin 2001, Toulouse.
Protection of workers against hazardous airborne dusts has received considerable attention as part of the overall emphasis on the minimization of various occupational exposures. Aerosol sampling is a well-recognized tool for assessing these hazards. However, industries in different countries utilize different aerosol sampling methodologies for exposure assessment.
These methodologies may also vary among specific industries being based on their specific guidelines and regulations. Thus, the investigators and regulators often experience difficulties when comparing aerosol sampling data. There are two main aspects of this problem that need to be addressed. First, some guidelines recommend personal sampling while others advise to employ stationary sampling. Second, a variety of samplers of both types, which differ from
each other with respect to their sampling efficiencies, are currently used in the workplaces.
In the nuclear fuel handling facilities in France and many other countries, the air monitoring is performed primarily by stationary samplers. The choice is determined by the purpose of the monitoring which is to provide warnings against significantly elevated levels of airborne radioactive materials. Although stationary sampling protocols were not defined to assess the personal exposure of workers to airborne radioactive particles, they are sometimes used to estimate the worker exposure in occupational environments. Since May 1996, the 96/29/EURATOM Directive allowed (since May 1996) using aerosol sampling measurements, including those of the particle size distribution and the particle concentration,
to assess the effective dose resulting from the workers’ inhalation of airborne radionuclides.
The question now is how to adequately measure the inhalable aerosol: with the stationary or personal sampling technique. Both techniques have their advantages for the purpose.
Therefore, a research program has been established with the final objective to provide technical guidelines on air sampling in nuclear facilities that would be useful for estimating the degree of the workers’ exposure to airborne particles.
The field studies conducted in the workplaces have revealed significant differences in the data obtained with different aerosol samplers. This could be attributed to two phenomena: the particle transport from the source to the sampling point and the aerosol sampling efficiency of a specific sampler. The airborne particle transport throughout the workplace is strongly dependent on the source characteristics and the airflow patterns in the environment. The
placement of the aerosol sampler is also an important issue in quantifying the particle transport efficiency and, consequently, the evolution of the aerosol concentration and size distribution from the source to the sampler (Whicker et al., 1997). The sampling efficiency depends on the sampler’s design and the microenvironment characteristics, such as theambient air velocity. When comparing the data obtained with different samplers in the workplaces, it is difficult to identify which of the above two phenomena had the most
significant effect on their differences.
This paper describes a preliminary study that has two specific aims:
- To design an experimental facility, which includes the polydisperse aerosol generation system and the reference sampling system. This facility should be capable to conduct sampling studies under various air mixing and air exchange conditions ranging from the calm air (or slightly-disturbed, low air movement environments) to well-ventilated indoor areas.
- To evaluate the capability of our methodology and validate the experimental protocol through determining the sampling performance for three types of aerosol samplers in calm air environments while collecting airborne particles of a specific size.
This work has been done with the collaboration of the Center for Health-Related , the University of Cincinnati, USA firstname.lastname@example.org, the Institut de Protection et de Sûreté Nucléaire, France ,email@example.com