• Publication Date:
  • Publication Type:
    Final Rule
  • Fed Register #:
  • Standard Number:
  • Title:
    Air Contaminants Correction


Occupational Safety and Health Administration

29 CFR Part 1910

RIN 1218-A826

Air Contaminants

ACTION: Correction

In rule document 93-15292 beginning on page 35338 in the issue of Wednesday, June 30, 1993 on page 35351, table Z-3 was published incorrectly and should read as set forth below:

Substance mppcf(a) mg/m(3)
Crystalline 250(b) 10 mg/m(3)(e)
Quartz (Respirable) -------- ----------
%SiO(2)+5 %SiO(2)+2
30 mg/m(3)
Quartz (Total Dust) ---------
Cristobalite: Use 1/2 the value
calculated from the count or mass
formulae for quartz
Tridymite: Use 1/2 the value calculated
from the formulae for quartz
Amorphous, including natural diatomaceous 80 mg/m(3)
earth 20 --------
Silicates(less than 1% crystalline
Mica 20
Soapstone 20
Talc (not containing asbestos) 20(c)
Talc (Containing asbestos) Use asbestos
Tremolite, asbestiform (see 29 CFR
Portland Cement 50
Graphite (Natural) 15
Coal Dust:
2.4 mg/m3(e)
Respirable fraction less than 5% SiO(2) ------------
Respirable fraction greater than 5%
SiO(2) 10 mg/m3 (e)
Inert or Nuisance Dust:(d)
Respirable fraction 15 5 mg/m(3)
Total dust 50 15 mg/m(3)
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 show 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
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/m(3) in the table for coal dust is 4.5 mg/m(3).