This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Kuschner, W. G. Search for Related Content PubMed PubMed Citation Articles by Kuschner, W. G.

Measuring Airborne Particulates with a Light Scattering Monitor

In their article analyzing indoor air quality in the homes of patients with chronic obstructive pulmonary disease, Dr. Osman and colleagues describe measuring particulate matter with a diameter of 2.5 µm or less, expressed as µg/m³, using a DustTrak monitor (TSI, Inc., Shoreview, MN) (1). The DustTrak instrument is a light scattering monitor which estimates the total mass concentration of a source by counting the total number of particles and then multiplying the result by a uniform particle mass. However, the mass concentrations calculated by this instrument are generated with the assumption that all particles are of uniform size and mass. Because particle volumes and weights can vary depending on the source from which they were generated, determining the mass concentration for all particles with this assumption can generate erroneous estimates.

To correct for this limitation, the authors should have calibrated the concentrations calculated by the DustTrak monitor to those generated by an integrated filter mass collection unit in both the indoor and outdoor settings. The "calibration factor" the authors cited and used in their investigation may have been appropriate for the referenced studies (2, 3), but it may not have been correct for either the indoor or outdoor sources in their investigation. The appropriate calibration factor for the DustTrak monitor can only be established through serial side-by-side comparisons against gravimetric samplers. The authors' report of high intermachine reliability between two DustTrak monitors establishes that the measurements of the monitors were precise; however, for the reason delineated above, it does not confirm that the measurements were accurate.

Ware G. Kuschner

U.S. Department of Veterans Affairs
Palo Alto Health Care System
Palo Alto, California

FOOTNOTES

Conflict of Interest Statement: The author has no financial relationship with a commercial entity that has an interest in the subject of this manuscript.

REFERENCES

1. Osman LM, Douglas JG, Garden C, Reglitz K, Lyon J, Gordon S, Ayres JG. Indoor air quality in homes of patients with chronic obstructive pulmonary disease. Am J Respir Crit Care Med 2007;176:465–472.[Abstract/Free Full Text]
2. Vojta PJ, Friedman W, Marker DA, Clickner R, Rogers JW, Viet SM, Muilenberg ML, Thorne PS, Arbes SJ Jr, Zeldin DC. First National Survey of Lead and Allergens in Housing: survey design and methods for the allergen and endotoxin components. Environ Health Perspect 2002;110:527–532.[Medline]
3. Jones PW, Quirk FH, Baveystock CM, Littlejohns P. A self-complete measure of health status for chronic airflow limitation: the St. George's Respiratory Questionnaire. Am Rev Respir Dis 1992;145:1321–1327.[Medline]

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Kuschner, W. G. Search for Related Content PubMed PubMed Citation Articles by Kuschner, W. G.