Methods used by the United States National Institute for Occupational Safety and Health to monitor crystalline silica.
Scand J Work, Environ & Health 1995 Sep; 21(Suppl 2):35-38
Methods used by NIOSH to monitor exposures to crystalline silica (14808607) dusts were discussed. Analytical methods used by NIOSH to determine silica concentrations in workplace air were summarized. There were four currently used NIOSH methods for determining silica in dust samples. They were based on three instrumental techniques: colorimetry, denoted method 7601; X-ray powder diffraction (XRD), denoted method 7500; and infrared spectroscopy (IR), two methods denoted 7602 and 7603. The sample collection for the four methods was similar. Breathing zone samples were collected by a 10 millimeter Dorr-Oliver nylon cyclone (DO cyclone) and a polyvinyl- chloride (PVC) filter. The cyclone removed the nonrespirable particles from the sample allowing only the respirable particles to be collected on the filters. The samples then were subjected to ashing or chemical dissolution to remove the PVC filter from the collected dust before analysis. The limit of detection was approximately 5 micrograms (microg) per sample for each of the four methods; however, accuracy was poor, especially at low filter loadings, 30microg/sample or lower. Filter loadings of this magnitude frequently occurred when concentrations in the workplace air approached the NIOSH recommended standard, 50microg per cubic meter. Improvements in the analytical procedures over the past few years were discussed. Laboratory proficiency has been improved following implementation of the Proficiency Analytical Testing Program, a program administered by the American Industrial Hygiene Association.
NIOSH-Author; Quartz-dust; Analytical-methods; Infrared-spectroscopy; X-ray-analysis; Occupational-exposure; Industrial-hygiene; Dust-analysis; Respirable-dust
Scandinavian Journal of Work, Environment and Health