Ann. occup. Hyg., Vol. 47, No. 1, pp. 91, 2003
© 2003 British Occupational Hygiene Society
Published by Oxford University Press
Letters to the Editor |
Deposited Submicrometer Particulate
Department of Health & Human Services, National Institute for Occupational Safety and Health, 1095 Willowdale Road, Morgantown, WV 26505, USA
Received 23 September 2002;
Because of the interest generated recently in the work described in a paper in the Inhaled Particles IX proceedings (McCawley et al., 2002), we want to make sure there is absolute clarity about a number of points involving current appropriateness of implementation.
The criterion for deposited submicrometer particulate (DSP) was proposed by McCawley (1999) in an American Conference of Governmental Industrial Hygienists’ (ACGIH) publication, as part of the product of an ACGIH committee, and was a recommendation for consideration of a new approach for particle size-selective sampling. This recommendation has not been adopted either by the ACGIH, as a whole, or in part by the TLV (threshold limit value) committee of the ACGIH, as a guideline for sampling at this point in time. We wish to make it entirely clear that this is the case, particularly to anyone not familiar with the process the ACGIH uses to adopt their sampling guidelines.
The DSP criterion is for a specific breathing pattern as given in the above reference, but other breathing patterns have also been compared, specifically in the reference to the work by Hornsby-Myers (2000).
It is believed that using the impactor did not change the particle size distribution in the size range <0.5 µm. It is also important to re-emphasize that placing the impactor in front of the inlet of the filter assembly may significantly change the collection efficiency of the filter assembly; this configuration has not been tested in the laboratory and thus the accuracy of the results is unknown. These configurations should not be used to collect data until their precision and accuracy have been determined using accepted laboratory methods.
We hope these clarifications will avoid any possible confusion about our interpretation of the results described in the recent article, and suggest these methods not be implemented until the aforementioned issues have been addressed.
REFERENCES
Hornsby-Myers J. (2000) Use of track-etched polycarbonate filters in series to mimic the total human lung deposition in the ultrafine and fine range from 0.03 to 0.40 µm. Masters thesis, West Virginia University. http://etd.wvu.edu7/ETDS/El 732/Homsby_Myers_J_Thesis.pdf
McCawley M. (1999) Particle size-selective criteria for deposited submicrometer particles. In Vincent, JH editor. Particle size selective sampling for particulate in air contaminants. Cincinnati, OH: American Conference of Governmental Industrial Hygienists.
McCawley M, Martin S, Moyer E, Berakis M, Hornsby-Myers J, Kent M. (2002) Development of a filter assembly to match the deposition of ultrafine aerosol in the lung: a pilot study with beryllium. Ann Occup Hyg; 46 (suppl. 1): 215–8.
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