There is not one crystalline silica exposure limit for all cases. Rather, the limit is derived from a calculation that takes into account the percentage of quartz, cristobalite, tridymite, and respirable dust specific to your particular work-site.
To determine the limit and compare it to the actual amount, you can:
You will supply certain data and the Genius will make some calculations to produce three different number:
||This number is the calculated permissible exposure limit for
dust to which the worker may be exposed. It uses the data you supplied and
is based on the percent crystalline silica in the sample. For example: 1.6
||This number is the actual amount of dust that is in your
work environment, for example: 4.8 mg/m3
||This number is derived by dividing the exposure by the PEL,
for example: 4.8 / 1.6 = 3.0 If the severity number is higher than 1.0 you
are above the limit. If the severity number is less than 1.0 you are below
The Genius performs calculations for a respirable dust sample. If your sample is collected as a total dust sample,
you will need to make adjustments to the PEL and Severity the Genius calculates.
|Permissible Exposure Limit for Crystalline Silica
regulation 29 CFR 1910.1000 Table Z-3 is used to determine the exposure limits for crystalline silica. Though this regulation is under the General
Industry Standard, crystalline silica exposures in the Construction and Maritime
Industries are subject to this same limit. Regulating these industries under the General
Industry Standard is specifically addressed in Appendix E of the OSHA Special Emphasis
Program (SEP) for Silicosis.
There are also limits on
coal dust and amorphous silica.