TABLE Z-3 Mineral Dusts
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Substance | mppcf a | mg/m3 |
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Silica: Crystalline | | |
Quartz (Respirable) . . . . . . . . . . . . . . . . . . |
250b %SiO2+5 |
10 mg/m3 e %SiO2+2 |
Quartz (Total Dust) . . . . . . . . . . . . . . . . . . |
. . . . . . . . . |
30 mg/m3 %SiO2+2 |
- Cristobalite: Use ½ the value calculated from the count or mass formulae for quartz.
- Tridymite: Use ½ the value calculated from the formulae for quartz.
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|
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Amorphous, including natural diatomaceous earth |
20 | 80 mg/m3 %SiO2 |
Silicates (less than 1% crystalline silica): | |
|
Mica . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . | 20 | |
Soapstone . . . . . . . . . . . . . . . . . . . . . . . . . . | 20 | |
Talc (not containing asbestos) . . . . . . . . . . . . | 20c | |
Talc (containing asbestos) Use asbestos limit | | |
Tremolite, asbestiform (see 29 CFR 1910.1001) | | |
Portland cement . . . | 50 | |
Graphite (Natural) . . . . . . . . . . . . . . . . . . . . . . | 15 | |
Coal Dust: | | |
Respirable fraction less than 5% SiO2 . . . . . . . . | . . . . . . . . . | 2.4 mg/m3 e |
Respirable fraction greater than 5% SiO2 . . . . . . | . . . . . . . . . | 10 mg/m3 e %SiO2+2 |
Inert or Nuisance Dust:d | | |
Respirable fraction . . . . . . . . . . . . . . . . . . . | 15 | 5 mg/m3 |
Total dust . . . . . . . . . . . . . . . . . . . . . . . . | 50 | 15 mg/m3 |
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Note -- Conversion factors - mppcf X 35.3 = million particles per
cubic meter = particles per c.c.
a Millions of particles per cubic foot of air, based on
impinger samples counted by light-field techniques.
b The percentage of crystalline silica in the formula is
the amount determined from airborne samples, except in those
instances in which other methods have been shown to be applicable.
c Containing less than 1% quartz; if 1% quartz or more,
use quartz limit.
d All inert or nuisance dusts, whether mineral,
inorganic, or organic, not listed specifically by substance name are
covered by this limit, which is the same as the Particulates Not
Otherwise Regulated (PNOR) limit in Table Z-1.
e Both concentration and percent quartz for the
application of this limit are to be determined from the fraction
passing a size-selector with the following characteristics:
Aerodynamic diameter (unit density sphere) | Percent passing selector |
2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . | 90 |
2.5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . | 75 |
3.5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . | 50 |
5.0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . | 25 |
10 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . | 0 |
The measurements under this note refer to the use of an AEC (now
NRC) instrument. The respirable fraction of coal dust is determined
with an MRE; the figure corresponding to that of 2.4 mg/m3 in the
table for coal dust is 4.5 mg/m3.
[Note: This document was changed to an html version as of 11/24/2004]
[58 FR 35340, June 30, 1993; 58 FR 40191, July 27, 1993, as amended at 61 FR 56831, Nov. 4, 1996; 62 FR 1600, Jan. 10, 1997; 62 FR 42018, Aug. 4,1997]
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