Pocket Guide cover

Appendices to the NIOSH Pocket Guide to Chemical Hazards


APPENDICES

APPENDIX A - NIOSH Potential Occupational Carcinogens
APPENDIX B - Thirteen OSHA-Regulated Carcinogens
APPENDIX C - Supplementary Exposure Limite
APPENDIX D - Substances with No Established RELs
APPENDIX E - OSHA Respirator Requirements for Selected Chemicals
APPENDIX F - Miscellaneous Notes
APPENDIX G - 1989 Air Contaminants Update Project: Exposure Limits NOT in Effect



Type C & CE - Definitions for Type C and Type CE Respirators


APPENDIX A
NIOSH Potential Occupational Carcinogens

New Policy

      For the past 20 plus years, NIOSH has subscribed to a carcinogen policy that was published in 1976 by Edward J. Fairchild, II, Associate Director for Cincinnati Operations, which called for "no detectable exposure levels for proven carcinogenic substances" (Annals of the New York Academy of Sciences, 271:200-207, 1976). This was in response to a generic OSHA rulemaking on carcinogens. Because of advances in science and in approaches to risk assessment and risk management, NIOSH has adopted a more inclusive policy. NIOSH recommended exposure limits (RELs) will be based on risk evaluations using human or animal health effects data, and on an assessment of what levels can be feasibly achieved by engineering controls and measured by analytical techniques. To the extent feasible, NIOSH will project not only a no-effect exposure, but also exposure levels at which there may be residual risks. This policy applies to all workplace hazards, including carcinogens, and is responsive to Section 20(a)(3) of the Occupational Safety and Health Act of 1970, which charges NIOSH to "... describe exposure levels that are safe for various periods of employment, including but not limited to the exposure levels at which no employee will suffer impaired health or functional capacities or diminished life expectancy as a result of his work experience."

      The effect of this new policy will be the development, whenever possible, of quantitative RELs that are based on human and/or animal data, as well as on the consideration of technological feasibility for controlling workplace exposures to the REL. Under the old policy, RELs for most carcinogens were non-quantitative values labeled "lowest feasible concentration (LFC)." [Note: There are a few exceptions to LFC RELs for carcinogens (e.g., RELs for asbestos, formaldehyde, benzene, and ethylene oxide are quantitative values based primarily on analytical limits of detection or technological feasibility). Also, in 1989, NIOSH adopted several quantitative RELs for carcinogens from OSHA's permissible exposure limit (PEL) update.]

      Under the new policy, NIOSH will also recommend the complete range of respirators (as determined by the NIOSH Respirator Decision Logic) for carcinogens with quantitative RELs. In this way, respirators will be consistently recommended regardless of whether a substance is a carcinogen or a non-carcinogen.

Old Policy

      In the past, NIOSH identified numerous substances that should be treated as potential occupational carcinogens even though OSHA might not have identified them as such. In determining their carcinogenicity, NIOSH used the OSHA classification outlined in 29 CFR 1990.103, which states in part:

Potential occupational carcinogen means any substance, or combination or mixture of substances, which causes an increased incidence of benign and/or malignant neoplasms, or a substantial decrease in the latency period between exposure and onset of neoplasms in humans or in one or more experimental mammalian species as the result of any oral, respiratory or dermal exposure, or any other exposure which results in the induction of tumors at a site other than the site of administration. This definition also includes any substance which is metabolized into one or more potential occupational carcinogens by mammals.
      When thresholds for carcinogens that would protect 100% of the population had not been identified, NIOSH usually recommended that occupational exposures to carcinogens be limited to the lowest feasible concentration. To ensure maximum protection from carcinogens through the use of respiratory protection, NIOSH also recommended that only the most reliable and protective respirators be used. These respirators include (1) a self-contained breathing apparatus (SCBA) that has a full facepiece and is operated in a positive-pressure mode, or (2) a supplied-air respirator that has a full facepiece and is operated in a pressure-demand or other positive-pressure mode in combination with an auxiliary SCBA operated in a pressure-demand or other positive-pressure mode.

Recommendations to be Revised

      The RELs and respirator recommendations for carcinogens listed in this edition of the Pocket Guide still reflect the old policy. Changes in the RELs and respirator recommendations that reflect the new policy will be included in future editions.

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APPENDIX B
Thirteen OSHA-Regulated Carcinogens

      Without establishing PELs, OSHA promulgated standards in 1974 to regulate the industrial use of 13 chemicals identified as potential occupational carcinogens.

      Exposures of workers to these 13 chemicals are to be controlled through the required use of engineering controls, work practices, and personal protective equipment, including respirators. See 29 CFR 1910.1003-1910.1016 for specific details of these requirements.

      Respirator selections in the Pocket Guide are based on NIOSH policy, which considers the 13 chemicals to be potential occupational carcinogens.

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APPENDIX C
Supplementary Exposure Limits

Aldehydes (Low-Molecular-Weight)

      Exposure to acetaldehyde has produced nasal tumors in rats and laryngeal tumors in hamsters, and exposure to malonaldehyde has produced thyroid gland and pancreatic islet cell tumors in rats. NIOSH therefore recommends that acetaldehyde and malonaldehyde be considered potential occupational carcinogens in conformance with the OSHA carcinogen policy.

      Testing has not been completed to determine the carcinogenicity of acrolein, butyraldehyde (CAS#: 123-72-8), crotonaldehyde, glutaraldehyde, glyoxal (CAS#: 107-22-2), paraformaldehyde (CAS#: 30525-89-4), propiolaldehyde (CAS#: 624-67-9), propionaldehyde (CAS#: 123-38-6), and n-valeraldehyde, nine related low-molecular-weight-aldehydes.

      However, the limited studies to date indicate that these substances have chemical reactivity and mutagenicity similar to acetaldehyde and malonaldehyde. Therefore, NIOSH recommends that careful consideration should be given to reducing exposures to these nine related aldehydes.

      Further information can be found in the "NIOSH Current Intelligence Bulletin 55: Carcinogenicity of Acetaldehyde and Malonaldehyde, and Mutagenicity of Related Low-Molecular-Weight Aldehydes" [DHHS (NIOSH) Publication No. 91-112.]

Asbestos

      NIOSH considers asbestos to be a potential occupational carcinogen and recommends that exposures be reduced to the lowest feasible concentration. For asbestos fibers >5 micrometers in length, NIOSH recommends a REL of 100,000 fibers per cubic meter of air (100,000 fibers/m3), which is equal to 0.1 fiber per cubic centimeter of air (0.1 fiber/cm3), as determined by a 400-liter air sample collected over 100 minutes in accordance with NIOSH Analytical Method #7400. Airborne asbestos fibers are defined as those particles having (1) an aspect ratio of 3 to 1 or greater and (2) the mineralogic characteristics (that is, the crystal structure and elemental composition) of the asbestos minerals and their nonasbestiform analogs. The asbestos minerals are defined as chrysotile, crocidolite, amosite (cummingtonite-grunerite), anthophyllite, tremolite, and actinolite. In addition, airborne cleavage fragments from the nonasbestiform habits of the serpentine minerals antigorite and lizardite, and the amphibole minerals contained in the series cummingtonite-grunerite, tremolite-ferroactinolite, and glaucophane-riebeckite should also be counted as fibers provided they meet the criteria for a fiber when viewed microscopically.

      As found in 29 CFR 1910.1001, the OSHA PEL for asbestos fibers (i.e., actinolite asbestos, amosite, anthophyllite asbestos, chrysotile, crocidolite, and tremolite asbestos) is an 8-hour TWA airborne concentration of 0.1 fiber (longer than 5 micrometers and having a length-to-diameter ratio of at least 3 to 1) per cubic centimeter of air (0.1 fiber/cm3), as determined by the membrane filter method at approximately 400X magnification with phase contrast illumination. No worker should be exposed in excess of 1 fiber/cm3 (excursion limit)as averaged over a sampling period of 30 minutes.

Benzidine-, o-Tolidine, and o-Dianisidine-based Dyes

      In December 1980, OSHA and NIOSH jointly published the Health Hazard Alert: Benzidine-, o-Tolidine-, and o-Dianisidine-based Dyes.

      In this Alert, OSHA and NIOSH concluded that benzidine and benzidine-based dyes were potential occupational carcinogens and recommended that worker exposure be reduced to the lowest feasible level.

      OSHA and NIOSH further concluded that o-tolidine and o-dianisidine (and dyes based on them) may present a cancer risk to workers and should be handled with caution and exposure minimized.

Carbon Black

      NIOSH considers "Carbon Black" to be the material consisting of more than 80% elemental carbon, in the form of near-spherical colloidal particles and coalesced particle aggregates of colloidal size, that is obtained by the partial combustion or thermal decomposition of hydrocarbons. The NIOSH REL (10-hour TWA) for carbon black is 3.5 mg/m3. Polycyclic aromatic hydrocarbons (PAHs), particulate polycyclic organic material (PPOM), and polynuclear aromatic hydrocarbons (PNAs) are terms frequently used to describe various petroleum-based substances that NIOSH considers to be potential occupational carcinogens. Since some of these aromatic hydrocarbons may be formed during the manufacture of carbon black (and become adsorbed on the carbon black), the NIOSH REL (10-hour TWA) for carbon black in the presence of PAHs is 0.1 mg PAHs/m3 (measured as the cyclohexane-extractable fraction). The OSHA PEL (8-hour TWA) for carbon black is 3.5 mg/m3.

Chloroethanes

      NIOSH considers ethylene dichloride; hexachloroethane; 1,1,2,2-tetrachloroethane; and 1,1,2-trichloroethane; to be potential occupational carcinogens.

      Additionally, NIOSH recommends that the other five chloroethane compounds:

be treated in the workplace with caution because of their structural similarity to the four chloroethanes shown to be carcinogenic in animals.

Chromic Acid and Chromates (as CrO3), Chromium(II) and Chromium(III) Compounds (as Cr), and Chromium Metal (as Cr)

      The NIOSH REL (10-hour TWA) is 0.001 mg Cr(VI)/m3 for all hexavalent chromium [Cr(VI)] compounds. NIOSH considers all Cr(VI) compounds (including chromic acid, tert-butyl chromate, zinc chromate, and chromyl chloride) to be potential occupational carcinogens.

      The NIOSH REL (8-hour TWA) is 0.5 mg Cr/m3 for chromium metal and chromium(II) and chromium(III) compounds.

      The OSHA PEL is 0.1 mg CrO3/m3 (ceiling) for chromic acid and chromates (including tert-butyl chromate with a "skin" designation and zinc chromate); 0.5 mg Cr/m3 (8-hour TWA) for chromium(II) and chromium(III) compounds; and 1 mg Cr/m3 (8-hour TWA) for chromium metal and insoluble salts.

Coal Tar Pitch Volatiles

      NIOSH considers coal tar products (i.e., coal tar, coal tar pitch, or creosote) to be potential occupational carcinogens; the NIOSH REL (10-hour TWA) for coal tar products is 0.1 mg/m3 (cyclohexane-extractable fraction).

      The OSHA PEL (8-hour TWA) for coal tar pitch volatiles is 0.2 mg/m3 (benzene-soluble fraction). OSHA defines "coal tar pitch volatiles" in 29 CFR 1910.1002 as the fused polycyclic hydrocarbons that volatilize from the distillation residues of coal, petroleum (excluding asphalt), wood, and other organic matter and includes substances such as anthracene, benzo(a)pyrene (BaP), phenanthrene, acridine, chrysene, pyrene, etc.

Coke Oven Emissions

      The production of coke by the carbonization of bituminous coal leads to the release of chemically-complex emissions from coke ovens that include both gases and particulate matter of varying chemical composition.

      The emissions include coal tar pitch volatiles (e.g., particulate polycyclic organic matter [PPOM], polycyclic aromatic hydrocarbons [PAHs], and polynuclear aromatic hydrocarbons [PNAs]), aromatic compounds (e.g., benzene and beta-naphthylamine), trace metals (e.g., arsenic, beryllium, cadmium, chromium, lead, and nickel), and gases (e.g., nitric oxides and sulfur dioxide).

Cotton Dust (raw)

      NIOSH recommends reducing exposures to cotton dust to the lowest feasible concentration to reduce the prevalence and severity of byssinosis; the REL is <0.200 mg/m3 (as lint-free cotton dust).

      As found in OSHA Table Z-1 (29 CFR 1910.1000), the PEL for cotton dust (raw) is 1 mg/m3 for the cotton waste processing operations of waste recycling (sorting, blending, cleaning, and willowing) and garnetting.

      PELs for other sectors (as found in 29 CFR 1910.1043) are 0.200 mg/m3 for yarn manufacturing and cotton washing operations, 0.500 mg/m3 for textile mill waste house operations or for dust from "lower grade washed cotton" used during yarn manufacturing, and 0.750 mg/m3 for textile slashing and weaving operations.

      The OSHA standard in 29 CFR 1910.1043 does not apply to cotton harvesting, ginning, or the handling and processing of woven or knitted materials and washed cotton.

      All PELs for cotton dust are mean concentrations of lint-free, respirable cotton dust collected by the vertical elutriator or an equivalent method and averaged over an 8-hour period.

Lead

      NIOSH considers "Lead" to mean metallic lead, lead oxides, and lead salts (including organic salts such as lead soaps but excluding lead arsenate).

      The NIOSH REL for lead (8-hour TWA) is 0.050 mg/m3; air concentrations should be maintained so that worker blood lead remains less than 0.060 mg Pb/100 g of whole blood.

      OSHA considers "Lead" to mean metallic lead, all inorganic lead compounds (lead oxides and lead salts), and a class of organic compounds called soaps; all other lead compounds are excluded from this definition.

      The OSHA PEL (8-hour TWA) is 0.050 mg/m3; other OSHA requirements can be found in 29 CFR 1910.1025. The OSHA PEL (8-hour TWA) for lead in "non-ferrous foundries with less than 20 employees" is 0.075 mg/m3.

Mineral Dusts

      The OSHA PELS for "mineral dusts" listed below are from Table Z-3 of 29 CFR 1910.1000. The OSHA PEL (8-hour TWA) for crystalline silica (as respirable quartz) is either 250 mppcf divided by the value "%SiO2 + 5" or 10 mg/m3 divided by the value "%SiO2 + 2." The OSHA PEL (8-hour TWA) for crystalline silica (as total quartz) is 30 mg/m3 divided by the value "%SiO2 + 2." The OSHA PELs (8-hour TWAs) for cristobalite and tridymite are « the values calculated above using the count or mass formulae for quartz.

      The OSHA PEL (8-hour TWA) for amorphous silica (including diatomaceous earth) is either 80 mg/m3 divided by the value "%SiO2," or 20 mppcf.

      The OSHA PELs (8-hour TWAs) for talc (not containing asbestos), mica, and soapstone are 20 mppcf. The OSHA PEL (8-hour TWA) for portland cement is 50 mppcf. The OSHA PEL (8-hour TWA) for graphite (natural) is 15 mppcf. The PELs for talc (not containing asbestos), mica, soapstone, and portland cement are applicable if the material contains less than 1% crystalline silica.

      The OSHA PEL (8-hour TWA) for coal dust (as the respirable fraction) containing less than 5% SiO2 is 2.4 mg/m3 divided by the value "%SiO2 + 2." The OSHA PEL (8-hour TWA) for coal dust (as the respirable fraction) containing greater than or equal to 5% SiO2 is 10 mg/m3 divided by the value "%SiO2 + 2."

NIAX® Catalyst ESN

      In May 1978, OSHA and NIOSH jointly published the Current Intelligence Bulletin (CIB) 26: NIAX® Catalyst ESN.

      In this CIB, OSHA and NIOSH recommended that occupational exposure to NIAX® Catalyst ESN, its components, dimethylaminopropionitrile and bis(2-(dimethylamino)ethyl)ether, as well as formulations containing either component, be minimized.

      Exposures should be limited to as few workers as possible, while minimizing workplace exposure concentrations with effective work practices and engineering controls.

      Exposed workers should be carefully monitored for potential disorders of the nervous and genitourinary system. Although substitution is a possible control measure, alternatives to NIAX® Catalyst ESN or its components should be carefully evaluated with regard to possible adverse health effects.

Trichloroethylene

      NIOSH considers trichloroethylene (TCE) to be a potential occupational carcinogen and recommends a REL of 2 ppm (as a 60-minute ceiling) during the usage of TCE as an anesthetic agent and 25 ppm (as a 10-hour TWA) during all other exposures.

Tungsten Carbide (Cemented)

      "Cemented tungsten carbide" or "hard metal" refers to a mixture of tungsten carbide, cobalt, and sometimes metal oxides or carbides and other metals (including nickel).

      When the cobalt (Co) content exceeds 2%, its contribution to the potential hazard is judged to exceed that of tungsten carbide.

      Therefore, the NIOSH REL (10-hour TWA) for cemented tungsten carbide containing >2% Co is 0.05 mg Co/m3; the applicable OSHA PEL is 0.1 mg Co/m3 (8-hour TWA). Nickel (Ni) may sometimes be used as a binder rather than cobalt.

      NIOSH considers cemented tungsten carbide containing nickel to be a potential occupational carcinogen and recommends a REL of 0.015 mg Ni/m3 (10-hour TWA).

      The OSHA PEL for Insoluble Nickel (i.e., a 1 mg Ni/m3 8-hour TWA) applies to mixtures of tungsten carbide and nickel.

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APPENDIX D
Substances with No Established RELs

      After reviewing available published literature, NIOSH provided comments to OSHA on August 1, 1988, regarding the "Proposed Rule on Air Contaminants" (29 CFR 1910, Docket No. H-020).

      In these comments, NIOSH questioned whether the PELs proposed (and listed below) for the following substances included in the Pocket Guide were adequate to protect workers from recognized health hazards:

      At that time, NIOSH also conducted a limited evaluation of the literature and concluded that the documentation cited by OSHA was inadequate to support the proposed PEL (as an 8-hour TWA) of 10 mg/m3 for alpha-alumina, benomyl, emery, glycerine (mist), graphite (synthetic), magnesium oxide fume, molybdenum (insoluble compounds as Mo), particulates not otherwise regulated, picloram, and rouge.

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APPENDIX E
OSHA Respirator Requirements for Selected Chemicals

Revisions to the OSHA Respiratory Protection Standard (29 CFR 1910.134) became effective on April 8, 1998.  Incorporated within the preamble of this ruling were changes to OSHA regulations for several chemicals or substances, which are listed as subheadings in blue text throughout this appendix.  These subheadings, which are also the titles of the affected standards within 29 CFR 1910 and 29 CFR 1926, are followed by the standard number(s) in parentheses and the OSHA respirator requirements.  Fit testing is required by OSHA for all tight-fitting air-purifying respirators.   Please consult 29 CFR 1910.134 for the full content of the changes that apply.  For all of the chemicals listed in this appendix, any respirators that are  permitted at higher environmental concentrations can be used at lower concentrations.

13 Carcinogens (4-Nitrobiphenyl, etc.) (1910.1003)

Employees engaged in handling operations involving the carcinogens listed below must be provided with, and required to wear and use, a half-mask filter-type respirator for dusts, mists, and fumes.  A respirator affording higher levels of protection than this respirator may be substituted.

 

bullet  2-Acetylaminofluorene

bullet  4-Dimethylaminoazobenezene

bullet  beta-Naphthylamine

bullet  4-Aminodiphenyl

bullet  Ethyleneimine

bullet  4-Nitrobiphenyl

bullet  Benzidine

bullet  Methyl chloromethyl ether

bullet  N-Nitrosodimethylamine

bullet  bis-Chloromethyl ether

bullet  alpha-Naphthylamine

bullet  beta-Propiolactone

bullet  3,3'-Dichlorobenzidine (and its salts)

 

 

Acrylonitrile (1910.1045)

 

Airborne Concentration

or Condition of Use

Respirator Type

< or =  20 ppm (parts per million)

(1) Chemical cartridge respirator with organic vapor cartridge(s) and half-mask facepiece; or (2) Supplied-air respirator with half-mask facepiece.

< or =  100 ppm or maximum

use concentration of

cartridges or canisters, whichever is lower

(1) Full-facepiece respirator with (A) organic vapor cartridges,

(B) organic vapor gas mask, chin-style, or (C) organic vapor gas mask canister, front- or back-mounted; (2) Supplied-air respirator with full facepiece; or (3) Self-contained breathing apparatus with full facepiece.

< or =  4,000 ppm

Supplied-air respirator operated in positive-pressure mode with full facepiece, helmet, suit, or hood.

> 4,000 ppm or unknown concentration

(1) Supplied-air and auxiliary self-contained breathing apparatus with full facepiece in positive-pressure mode; or (2) Self-contained breathing apparatus with full facepiece in positive-pressure mode.

Firefighting

Self-contained breathing apparatus with full facepiece in positive-pressure mode.

Escape

(1) Any organic vapor respirator; or

(2) Any self-contained breathing apparatus.

 

Arsenic, inorganic (1910.1018)

 

Requirements for Respiratory Protection for Inorganic Arsenic Particulate

Except for Those With Significant Vapor Pressure

Airborne Concentration

(as As) or Condition of Use

Required Respirator

< or =  100 µg/m3 (micrograms

per cubic meter)

(1) Half-mask air-purifying respirator equipped with high-efficiency filter*; or (2) Any half-mask supplied air respirator.

< or =  500 µg/m3

(1) Full facepiece air-purifying respirator equipped with high-efficiency filter*; (2) Any full-facepiece supplied-air respirator; or

(3) Any full-facepiece self-contained breathing apparatus.

< or =  10,000 µg/m3

(1) Powered air-purifying respirators in all inlet face coverings with high-efficiency filters*; or (2) Half-mask supplied-air respirators operated in positive-pressure mode.

< or =  20,000 µg/m3

Supplied-air respirator with full facepiece, hood, or helmet or suit, operated in positive-pressure mode.

> 20,000 µg/m3, unknown concentrations, or firefighting

Any full-facepiece self-contained breathing apparatus operated in positive-pressure mode.

* A high-efficiency filter means a filter that is at least 99.97% efficient against mono-disperesed particles of 0.3 µm (micrometers) in diameter or higher.

 

Requirements for Respiratory Protection for

Inorganic Arsenicals With Significant Vapor Pressure

Airborne Concentration

(as As) or Condition of Use

Required Respirator

< or =  100 µg/m3 (micrograms

per cubic meter)

(1) Half-mask* air-purifying respirator equipped with high-efficiency filter** and acid gas cartridge; or (2) Any half-mask* supplied-air respirator.

< or =  500 µg/m3

(1) Front- or back-mounted gas mask equipped with high-efficiency filter** and acid gas canister; (2) Any full-facepiece supplied-air respirator; or (3) Any full-facepiece self-contained breathing apparatus.

< or =  10,000 µg/m3

Half-mask* supplied-air respirator operated in positive-pressure mode.

< or =  20,000 µg/m3

Supplied-air respirator with full facepiece, hood, or helmet or suit, operated in positive-pressure mode.

> 20,000 µg/m3, unknown concentrations, or firefighting

Any full-facepiece self-contained breathing apparatus operated in positive-pressure mode.

* Half-mask respirators shall not be used for protection against arsenic trichloride, as it is rapidly absorbed through the skin.

** A high-efficiency filter means a filter that is at least 99.97% efficient against mono-disperesed particles of 0.3 µm (micrometers) in diameter or higher.

 

Asbestos (1910.1001 & 1926.1101)

 

Airborne Concentration

or Condition of Use

Required Respirator

< or =  1 f/cm3 (fibers per cubic centimeter) (10 X PEL)

Half-mask air-purifying respirator other than a disposable respirator, equipped with high-efficiency filters*.

< or =  5 f/cm3 (50 X PEL)

Full-facepiece air-purifying respirator equipped with high-efficiency filters*.

< or =  10 f/cm3 (100 X PEL)

Any powered air-purifying respirator equipped with high-efficiency filters* or any supplied-air respirator operated in continuous-flow mode.

< or =  100 f/cm3 (1,000 X PEL)

Full-facepiece supplied air respirator operated in pressure-demand mode.

> 100 f/cm3 (1,000 X PEL),

or unknown concentrations

Full-facepiece supplied-air respirator operated in pressure-demand mode, equipped with an auxiliary positive-pressure self-contained breathing apparatus.

* A high-efficiency filter means a filter that is at least 99.97% efficient against mono-dispersed particles of 0.3 µm (micrometers) in diameter or higher.

Benzene (1910.1028)

 

Airborne Concentration

or Condition of Use

Required Respirator

< or =  10 ppm (parts per million)

Half-mask air-purifying respirator with organic vapor cartridge.

< or =  50 ppm

(1) Full-facepiece respirator with organic vapor cartridges; or

(2) Full-facepiece gas mask with chin-style canisters*.

< or =  100 ppm

Full-facepiece powered air-purifying respirator with organic vapor canister*.

< or =  1,000 ppm

Supplied-air respirator with full facepiece in positive-pressure mode.

> 1,000 ppm or

unknown concentration

(1) Self-contained breathing apparatus with full facepiece in positive-pressure mode; or (2) Full-facepiece positive-pressure supplied-air respirator with auxiliary self-contained air supply.

Escape

(1) Any organic vapor gas mask; or (2) Any self-contained breathing apparatus with full facepiece.

Firefighting

Full-facepiece self-contained breathing apparatus in positive-pressure mode.

* Canisters must have a minimum service life of four (4) hours when tested at 150 ppm benzene, at a flow rate of 64 liters per minute (LPM), 25°C, and 85% relative humidity for non-powered air-purifying respirators.  The flow rate shall be 115 LPM and 170 LPM, respectively, for tight-fitting and loose-fitting powered air-purifying respirators.

 

1,3-Butadiene (1910.1051)

 

Airborne Concentration or Condition of Use

Required Respirator

< or =  5 ppm (parts per million)

Air-purifying half-mask or full-facepiece respirator equipped with approved butadiene or organic vapor cartridges or canisters.  Cartridges or canisters shall be replaced every 4 hours.

< or =  10 ppm

Air-purifying half-mask or full-facepiece respirator equipped with approved butadiene or organic vapor cartridges or canisters.  Cartridges or canisters shall be replaced every 3 hours.

< or =  25 ppm

(1) Air-purifying half-mask or full-facepiece respirator equipped with approved butadiene or organic vapor cartridges or canisters.  Cartridges or canisters shall be replaced every 2 hours;

(2) Any powered air-purifying respirator equipped with approved butadiene or organic vapor cartridges or canisters.  Cartridges or canisters shall be replaced every [1] hour; or (3) Continuous-flow supplied-air respirator equipped with a hood or helmet.

< or =  50 ppm

(1) Air-purifying full-facepiece respirator equipped with approved butadiene or organic vapor cartridges or canisters.  Cartridges or canisters shall be replaced every [1] hour; or (2) Powered air-purifying respirator (PAPR) equipped with a tight-fitting facepiece and approved butadiene or organic vapor cartridges.  PAPR cartridges shall be replaced every [1] hour.

< or =  1,000 ppm

Supplied-air respirator equipped with a half-mask or full facepiece and operated in a pressure-demand or other positive-pressure mode.

> 1,000 ppm, unknown concentration, or firefighting

(1) Self-contained breathing apparatus equipped with a full facepiece and operated in a pressure-demand or other positive-pressure mode; or (2) Any supplied-air respirator equipped with a full facepiece and operated in a pressure-demand or other positive-pressure mode in combination with an auxiliary self-contained breathing apparatus operated in a pressure-demand or other positive-pressure mode.

Escape from IDLH conditions

(IDLH is 2,000 ppm)

(1) Any positive-pressure self-contained breathing apparatus with an appropriate service life; or (2) Any air-purifying full-facepiece respirator equipped with a front- or back-mounted butadiene or organic vapor canister.

 

Cadmium (1910.1027 & 1926.1127)

 

Airborne Concentration or Condition of Use

Required Respirator

< or =  50 µg/m3 (micrograms

per cubic meter)

Half-mask, air-purifying respirator equipped with a high-efficiency filter*.

< or =  125 µg/m3

(1) Powered air-purifying respirator with a loose-fiting hood or helmet equipped with a high-efficiency filter*; or (2) Supplied-air respirator with a loose-fitting hood or helmet facepiece operated in continuous-flow mode.

< or =  250 µg/m3

(1) Full-facepiece air-purifying respirator equipped with a high-efficiency filter*; (2) Powered air-purifying respirator with a tight-fitting half-mask equipped with a high-efficiency filter*; or (3) Supplied-air respirator with a tight-fitting half-mask operated in continuous-flow mode.

< or =  1,250 µg/m3

(1) Powered air-purifying respirator with a tight-fitting full facepiece equipped with a high-efficiency filter*; or (2) Supplied-air respirator with a tight-fitting full facepiece operated in continuous-flow mode.

< or =  5,000 µg/m3

Supplied-air respirator with half-mask or full facepiece operated in pressure-demand or other positive-pressure mode.

> 5,000 µg/m3 or

unknown concentration

(1) Self-contained breathing apparatus with a full facepiece operated in pressure-demand or other positive-pressure mode; or (2) Supplied-air respirator with a full facepiece operated in pressure-demand or other positive-pressure mode and equipped with an auxiliary escape-type self-contained breathing apparatus operated in pressure-demand mode.

Firefighting

Self-contained breathing apparatus with full facepiece operated in pressure-demand or other positive-pressure mode.

Note: Quantitative fit testing is required for all tight-fitting air-purifying respirators where airborne concentration of cadmium exceeds 10 times the TWA PEL (10 X 5 µg/m3 = 50 µg/m3).  A full-facepiece respirator is required when eye irritation is expected.

 

* A high-efficiency filter means a filter that is at least 99.97% efficient against mono-dispersed particles of 0.3 µm (micrometers) in diameter or higher.

 

Coke oven emissions (1910.1029)

 

Airborne Concentration

Required Respirator

< or =  1500 µg/m3 (micrograms per cubic meter)

(1) Any particulate filter respirator for dust and mist except single-use respirator; or (2) Any particulate filter respirator or combination chemical cartridge and particulate filter respirator for coke oven emissions.

Any concentrations

(1) Type C supplied-air respirator operated in pressure-demand or continuous-flow mode; (2) Powered air-purifying particulate filter respirator for dust and mist; or (3) Powered air-purifying particulate filter respirator or combination chemical cartridge and particulate filter respirator for coke oven emissions.

 

Cotton dust (1910.1043)

 

Airborne Concentration

Required Respirator

< or =  5 X PEL

Disposable respirator* with a particulate filter.

< or =  10 X PEL

Quarter- or half-mask respirator, other than a disposable respirator, equipped with particulate filters.

< or =  100 X PEL

Full-facepiece respirator equipped with high-efficiency particulate filters**.

> 100 X PEL

Powered air-purifying respirator equipped with high-efficiency particulate filters.

* A disposable respirator means the filter element is an inseparable part of the respirator.

** A high-efficiency filter means a filter that is at least 99.97% efficient against mono-dispersed particles of 0.3 µm (micrometers) in diameter or higher.

 

Notes:

Self-contained breathing apparatus are not required but are permitted respirators.

 

Supplied-air respirators are not required but are permitted under the following conditions: 

Cotton dust concentration not greater than 10X the PEL: Any supplied air respirator;  not greater than 100X the PEL: Any supplied-air respirator with full facepiece, helmet, or hood; greater than 100X the PEL: Supplied-air respirator operated in positive-pressure mode.

 

1,2-Dibromo-3-chloropropane (1910.1044)

 

Airborne Concentration

or Condition of Use

Required Respirator

< or =  10 ppb (parts per billion)

(1) Any supplied-air respirator; or (2) any self-contained breathing apparatus.

< or =  50 ppb

(1) Any supplied-air respirator with full facepiece, helmet, or hood; or (2) any self-contained breathing apparatus with full facepiece.

< or =  1,000 ppb

Type C supplied-air respirator operated in pressure-demand or other positive-pressure or continuous-flow mode.

< or =  2,000 ppb

Type C supplied-air respirator with full facepiece operated in pressure-demand or other positive-pressure mode, or with full facepiece, helmet, or hood operated in continuous-flow mode.

> 2,000 ppb or entry and escape from unknown concentrations

(1) A combination respirator which includes a Type C supplied-air respirator with full facepiece operated in pressure-demand or other positive pressure or continuous-flow mode and an auxiliary self-contained breathing apparatus operated in pressure-demand or positive-pressure mode; or (2) Self-contained breathing apparatus with full facepiece operated in pressure-demand or other positive-pressure mode.

Firefighting

Self-contained breathing apparatus with full facepiece operated in pressure-demand or other positive-pressure mode.


 

Ethylene oxide (1910.1047)

 

Airborne Concentration or Condition of Use

Required Respirator

< or =  50 ppm (parts per million)

Full-facepiece respirator with ethylene oxide approved canister, front- or back-mounted.

< or =  2,000 ppm

(1) Positive-pressure supplied-air respirator equipped with full facepiece, hood, or helmet; or (2) Continuous-flow supplied-air respirator (positive-pressure) equipped with hood, helmet, or suit.

> 2,000 ppm or

unknown concentrations

(1) Positive-pressure self-contained breathing apparatus equipped with full facepiece; or (2) Positive-pressure full-facepiece supplied-air respirator equipped with an auxiliary positive-pressure self-contained breathing apparatus.

Firefighting

Positive-pressure self-contained breathing apparatus equipped with full facepiece.

Escape

Any respirator described above.

 

Formaldehyde (1910.1048)

 

Airborne Concentration or Condition of Use

Required Respirator

< or =  7.5 ppm (parts per million) (10 X PEL)

Full-facepiece respirator with cartridges or canisters specifically approved for protection against formaldehyde*.

< or =  75 ppm (100 X PEL)

(1) Full-face mask respirator with chin style or chest- or back-mounted type with industrial size canister specifically approved for protection against formaldehyde; or (2) Type C supplied-air respirator, demand type or continuous flow type, with full facepiece, hood, or helmet.

> 75 ppm (100 X PEL) or unknown concentrations (emergencies)

(1) Self-contained breathing apparatus with positive-pressure full-facepiece; or (2) Combination supplied-air, full-facepiece positive-pressure respirator with auxiliary self-contained air supply.

Firefighting

Self-contained breathing apparatus with positive-pressure in full facepiece.

Escape

(1) Self-contained breathing apparatus in demand or pressure-demand mode; or (2) Full-face mask respirator with chin-style or front- or back-mounted type industrial size canister specifically approved for protection against formaldehyde.

* A half-mask respirator with cartridges specifically approved for protection against formaldehyde can be substituted for the full-facepiece respirator providing that effective gas-proof goggles are provided and used in combination with the half-mask respirator.

 

Lead (1910.1025 & 1926.62)

 

Respirator Requirements of 1910.1025 (General Industry Lead Standard)

Airborne Concentration

or Condition of Use

Required Respirator

< or =  0.5 mg/m3 (milligrams per cubic meter) (10 X PEL)

Half-mask* air-purifying respirator equipped with high-efficiency filters**.

< or =  2.5 mg/m3 (50 X PEL)

Full-facepiece air-purifying respirator with high-efficiency filters**.

< or =  50 mg/m3 (1000 X PEL)

(1) Any powered air-purifying respirator with high-efficiency filters**; or

(2) Half-mask* supplied-air respirator operated in positive-pressure mode.

< or =  100 mg/m3 (2000 X PEL)

Supplied-air respirators with full facepiece, hood, helmet, or suit, operated in positive-pressure mode.

> 100 mg/m3, unknown concentration, or firefighting

Full-facepiece, self-contained breathing apparatus operated in positive-pressure mode.

* Full facepiece is required if the lead aerosols cause eye or skin irritation at the use concentrations.

 

** A high-efficiency filter means a filter that is at least 99.97% efficient against mono-dispersed particles of 0.3 µm (micrometers) in diameter or higher.

 

 

Respirator Requirements of 1926.62 (Construction Lead Standard)

Airborne Concentration

or Condition of Use

Required Respirator

< or =  0.5 mg/m3 (milligrams

per cubic meter)

(1) Half-mask* air-purifying respirator with high-efficiency filters**; or

(2) Half-mask* supplied-air respirator operated in demand (negative pressure) mode.

< or =  1.25 mg/m3

(1) Loose-fitting hood or helmet powered air-purifying respirator with high-efficiency filters**; or (2) Hood or helmet supplied-air respirator operated in a continuous-flow mode (e.g., Type CE abrasive blasting respirators operated in a continuous-flow mode).

< or =  2.5 mg/m3

(1) Full-facepiece air-purifying respirator with high-efficiency filters**;

(2) Tight-fitting powered air-purifying respirator with high-efficiency filters**; (3) Full-facepiece supplied-air respirator operated in demand mode; (4) Half-mask* or full-facepiece supplied-air respirator operated in a continuous-flow mode; or (5) Full-facepiece self-contained breathing apparatus operated in demand mode.

< or =  50 mg/m3

Half-mask* supplied-air respirator operated in pressure-demand or other positive-pressure mode.

< or =  100 mg/m3

Full-facepiece supplied-air respirator operated in pressure-demand or other positive-pressure mode (e.g., Type CE abrasive blasting respirators operated in a continuous-flow mode).

> 100 mg/m3, unknown concentration, or firefighting

Full-facepiece self-contained breathing apparatus in pressure-demand or other positive-pressure mode.

* Full facepiece is required if the lead aerosols cause eye or skin irritation at the use concentrations.

 

** A high-efficiency filter means a filter that is at least 99.97% efficient against mono-dispersed particles of 0.3 µm (micrometers) in diameter or higher.

 

Methylene chloride (1910.1052)

 

Airborne Concentration or Condition of Use

Required Respirator

< or =  625 ppm (parts

per million) (25 X PEL)

Continuous-flow supplied-air respirator, hood or helmet.

< or =  1250 ppm

(50 X PEL)

(1) Full-facepiece supplied-air respirator operated in negative-pressure (demand) mode; or (2) Full-facepiece self-contained breathing apparatus operated in negative-pressure (demand) mode.

< or =  5,000 ppm

(200 X PEL)

(1) Continuous-flow supplied-air respirator, full-facepiece; (2) Pressure-demand supplied-air respirator, full-facepiece; or (3) Positive-pressure full-facepiece self-contained breathing apparatus.

> 5,000 ppm or unknown concentration

(1) Positive-pressure full-facepiece self-contained breathing apparatus; or (2) Full-facepiece pressure-demand supplied-air respirator with an auxiliary self-contained air supply.

Firefighting

Positive-pressure full-facepiece self-contained breathing apparatus.

Emergency escape

(1) Any continuous-flow or pressure-demand self-contained breathing apparatus; or (2) Gas mask with organic vapor canister.

 

4,4'-Methylenedianiline (1910.1050 & 1926.60)

 

Airborne Concentration or Condition of Use

Required Respirator

< or =  10 X PEL

Half-mask respirator with high-efficiency* cartridge**.

< or =  50 X PEL

Full-facepiece respirator with high-efficiency* cartridge or canister**.

< or =  1,000 X PEL

Full-facepiece powered air-purifying respirator with high-efficiency* cartridge**.

> 1,000 X PEL or

unknown concentration

(1) Self-contained breathing apparatus with full facepiece in positive-pressure mode; or (2) Full-facepiece positive-pressure demand supplied-air respirator with auxiliary self-contained air supply.

Escape

(1) Any full-facepiece air-purifying respirator with high-efficiency* cartridges**; or (2) Any positive-pressure or continuous-flow self-contained breathing apparatus with full facepiece or hood.

Firefighting

Full-facepiece self-contained breathing apparatus in positive-pressure demand mode.

* A high-efficiency filter means a filter that is at least 99.97% efficient against mono-dispersed particles of 0.3 µm (micrometers) in diameter or higher.

** Combination High-Efficiency/Organic Vapor Cartridges shall be used whenever Methylenedianiline is in liquid form or a process requiring heat is used.

 

Vinyl Chloride (1910.1017)

 

Airborne Concentration

or Condition of Use

Required Respirator

< or =  10 ppm (parts per million)

(1) Combination Type C supplied-air respirator, demand type, with half facepiece, and auxiliary self-contained air supply; (2) Type C supplied-air respirator, demand type, with half facepiece; or (3) Any chemical cartridge respirator with an organic vapor cartridge which provides a service life of at least 1 hour for concentrations of vinyl chloride up to 10 ppm.

< or =  25 ppm

(1) Powered air-purifying respirator with hood, helmet, full or half facepiece, and a canister which provides a service life of at least 4 hours for concentrations of vinyl chloride up to 25 ppm; or (2) Gas mask with front- or back-mounted canister which provides a service life of at least 4 hours for concentrations of vinyl chloride up to 25 ppm.

< or =  100 ppm

(1) Combination Type C supplied-air respirator, demand type, with full facepiece, and auxiliary self-contained air supply; or (2) Open-circuit self-contained breathing apparatus with full facepiece, in demand mode; or (3) Type C supplied-air respirator, demand type, with full facepiece.

< or =  1,000 ppm

Type C supplied-air respirator, continuous-flow type, with full or half facepiece, helmet, or hood.

< or =  3,600 ppm

(1) Combination Type C supplied-air respirator, pressure demand type, with full or half facepiece, and auxiliary self-contained air supply; or (2) Combination type continuous-flow supplied-air respirator with full or half facepiece and auxiliary self-contained air supply.

> 3,600 ppm or

unknown concentration

Open-circuit self-contained breathing apparatus, pressure-demand type, with full facepiece.

 



Definitions for Type C and Type CE Respirators

 

The definitions below were obtained from the NIOSH Certified Equipment List, which is available on the NIOSH Web site (http://www.cdc.gov/niosh/npptl/topics/respirators/cel).

 

Type C Respirator:An airline respirator, for entry into and escape from atmospheres not immediately dangerous to life or health, which consists of a source of respirable breathing air, a hose, a detachable coupling, a control valve, orifice, a demand valve or pressure demand valve, and arrangement for attaching the hose to the wearer and a facepiece, hood, or helmet.

 

Type CE Respirator: A Type C supplied-air respirator equipped with additional devices designed to protect the wearer's head and neck against impact and abrasion from rebounding abrasive material, and with shielding material such as plastic, glass, woven wire, sheet metal, or other suitable material to protect the window(s) of facepieces, hoods, and helmets which do not unduly interfere with the wearer's vision and permit easy access to the external surface of such window(s) for cleaning.

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APPENDIX F
Miscellaneous Notes

Benzene


The final OSHA Benzene standard in 1910.1028 applies to all occupational exposures to benzene except some subsegments of industry where exposures are consistently under the action level (i.e., distribution and sales of fuels, sealed containers and pipelines, coke production, oil and gas drilling and production, natural gas processing, and the percentage exclusion for liquid mixtures); for the excepted subsegments, the benzene limits in Table Z-2 apply (i.e., an 8-hour TWA of 10 ppm, an acceptable ceiling of 25 ppm, and 50 ppm for a maximum duration of 10 minutes as an acceptable maximum peak above the acceptable ceiling).


Octachloronaphthalene

Pentachloronaphthalene

Tetrachloronaphthalene

Trichloronaphthalene


IDLH values for these four chloronaphthalene compounds are unknown.  The Documentation for Immediately Dangerous to Life or Health Concentrations identified "Effective" IDLH values, based on analogy with other chloronaphthalenes and the then-effective NIOSH Respirator Decision Logic (DHHS [NIOSH] Publication No. 87-108; http://www.cdc.gov/niosh/docs/87-108).  These values for respirator recommendations were determined by multiplying the NIOSH REL or OSHA PEL by an assigned protection factor of 10.  This assigned protection factor was used during the Standards Completion Program for deciding when the "most protective" respirators should be used for these four chemicals.  Listed below are the "Effective" IDLH values that were determined using 10 times the REL or PEL for each chemical.  For more information please consult the IDLH Documentation. 

 

 Chemical

NIOSH REL/OSHA PEL

"Effective" IDLH (10 X REL/PEL)

 Octachloronaphthalene

TWA 0.1 mg/m3 *

1 mg/m3

 Pentachloronaphthalene

TWA 0.5 mg/m3

5 mg/m3

 Tetrachloronaphthalene

TWA 5 mg/m3

50 mg/m3

 Trichloronaphthalene

TWA 2 mg/m3

20 mg/m3

* NIOSH also recommends a STEL of 0.3 mg/m3 for octachloronaphthalene; the TWA of 0.1 mg/m3 was used to calculate the "Effective" IDLH of 1 mg/m3.

 

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APPENDIX G
1989 Air Contaminants Update Project:
Exposure Limits NOT in Effect

Acetaldehyde TWA 100 ppm (180 mg/m3)
ST 150 ppm (270 mg/m3)
Acetic anhydrideC 5 ppm (20 mg/m3)
Acetone TWA 750 ppm (1800 mg/m3)
ST 1000 ppm (2400 mg/m3)
Acetonitrile TWA 40 ppm (70 mg/m3)
ST 60 ppm (105 mg/m3)
Acetylsalicyclic acid TWA 5 mg/m3
Acrolein TWA 0.1 ppm (0.25 mg/m3)
ST 0.3 ppm (0.8 mg/m3)
Acrylamide TWA 0.03 mg/m3 [skin]
Acrylic acid TWA 10 ppm (30 mg/m3) [skin]
Allyl alcohol TWA 2 ppm (5 mg/m3)
ST 4 ppm (10 mg/m3) [skin]
Allyl chloride TWA 1 ppm (3 mg/m3)
ST 2 ppm (6 mg/m3)
Allyl glycidyl ether TWA 5 ppm (22 mg/m3)
ST 10 ppm (44 mg/m3)
Allyl propyl disulfide TWA 2 ppm (12 mg/m3)
ST 3 ppm (18 mg/m3)
alpha-Alumina TWA 10 mg/m3 (total)
TWA 5 mg/m3 (resp)
Aluminum (pyro powders & welding fumes, as Al)TWA 5 mg/m3
Aluminum (soluble salts & alkyls, as Al) TWA 2 mg/m3
Amitrole TWA 0.2 mg/m3
Ammonia ST 35 ppm (27 mg/m3)
Ammonium chloride fumeTWA 10 mg/m3
ST 20 mg/m3
Ammonium sulfamate TWA 10 mg/m3 (total)
TWA 5 mg/m3 (resp)
Aniline (and homologs) TWA 2 ppm (8 mg/m3) [skin]
Atrazine TWA 5 mg/m3
Barium sulfate TWA 10 mg/m3 (total)
TWA 5 mg/m3 (resp)
Benomyl TWA 10 mg/m3 (total)
TWA 5 mg/m3 (resp)
Benzenethiol TWA 0.5 ppm (2 mg/m3)
Bismuth telluride (doped with selenium sulfide, as Bi2Te3)TWA 5 mg/m3
Borates, tetra, sodium salts (Anhydrous) TWA 10 mg/m3
Borates, tetra, sodium salts (Decahydrate)TWA 10 mg/m3
Borates, tetra, sodium salts (Pentahydrate)TWA 10 mg/m3
Boron oxide TWA 10 mg/m3
Boron tribromideC 1 ppm (10 mg/m3)
Bromacil TWA 1 ppm (10 mg/m3)
Bromine TWA 0.1 ppm (0.7 mg/m3)
ST 0.3 ppm (2 mg/m3)
Bromine pentafluoride TWA 0.1 ppm (0.7 mg/m3)
n-Butane TWA 800 ppm (1900 mg/m3)
2-Butanone TWA 200 ppm (590 mg/m3)
ST 300 ppm (885 mg/m3)
2-Butoxyethanol TWA 25 ppm (120 mg/m3) [skin]
n-Butyl acetate TWA 150 ppm (710 mg/m3)
ST 200 ppm (950 mg/m3)
Butyl acrylate TWA 10 ppm (55 mg/m3)
n-Butyl alcohol C 50 ppm (150 mg/m3) [skin]
sec-Butyl alcoholTWA 100 ppm (305 mg/m3)
tert-Butyl alcohol TWA 100 ppm (300 mg/m3)
ST 150 ppm (450 mg/m3)
n-Butyl glycidyl ether TWA 25 ppm (135 mg/m3)
n-Butyl lactate TWA 5 ppm (25 mg/m3)
n-Butyl mercaptanTWA 0.5 ppm (1.5 mg/m3)
o-sec-ButylphenolTWA 5 ppm (30 mg/m3) [skin]
p-tert-Butyltoluene TWA 10 ppm (60 mg/m3)
ST 20 ppm (120 mg/m3)
Calcium cyanamideTWA 0.5 mg/m3
Caprolactam Dust:
TWA 1 mg/m3
ST 3 mg/m3

Vapor:
TWA 5 ppm (20 mg/m3)
ST 10 ppm (40 mg/m3)
Captafol TWA 0.1 mg/m3
Captan TWA 5 mg/m3
Carbofuran TWA 0.1 mg/m3
Carbon dioxide TWA 10,000 ppm (18,000 mg/m3)
ST 30,000 ppm (54,000 mg/m3)
Carbon disulfideTWA 4 ppm (12 mg/m3)
ST 12 ppm (36 mg/m3) [skin]
Carbon monoxide TWA 35 ppm (40 mg/m3)
C 200 ppm (229 mg/m3)
Carbon tetrabromide TWA 0.1 ppm (1.4 mg/m3)
ST 0.3 ppm (4 mg/m3)
Carbon tetrachloride TWA 2 ppm (12.6 mg/m3)
Carbonyl fluorideTWA 2 ppm (5 mg/m3)
ST 5 ppm (15 mg/m3)
Catechol TWA 5 ppm (20 mg/m3) [skin]
Cesium hydroxideTWA 2 mg/m3
Chlorinated camphene TWA 0.5 mg/m3
ST 1 mg/m3 [skin]
Chlorine TWA 0.5 ppm (1.5 mg/m3)
ST 1 ppm (3 mg/m3)
Chlorine dioxideTWA 0.1 ppm (0.3 mg/m3)
ST 0.3 ppm (0.9 mg/m3)
Chloroacetyl chloride TWA 0.05 ppm (0.2 mg/m3)
o-Chlorobenzylidene malononitrile C 0.05 ppm (0.4 mg/m3) [skin]
Chlorodifluoromethane TWA 1000 ppm (3500 mg/m3)
Chloroform TWA 2 ppm (9.78 mg/m3)
1-Chloro-1-nitropropane TWA 2 ppm (10 mg/m3)
Chloropentafluoroethane TWA 1000 ppm (6320 mg/m3)
beta-Chloroprene TWA 10 ppm (35 mg/m3) [skin]
o-Chlorostyrene TWA 50 ppm (285 mg/m3)
ST 75 ppm (428 mg/m3)
o-Chlorotoluene TWA 50 ppm (250 mg/m3)
Chlorpyrifos TWA 0.2 mg/m3 [skin]
Coal dust TWA 2 mg/m3 (<5% SiO2)(resp dust)
TWA 0.1 mg/m3 (> or = 5% SiO2) (resp quartz)
Cobalt metal dust & fume, as Co) TWA 0.05 mg/m3
Cobalt carbonyl (as Co) TWA 0.1 mg/m3
Cobalt hydrocarbonyl (as Co) TWA 0.1 mg/m3
Crag® herbicide TWA 10 mg/m3 (total)
TWA 5 mg/m3 (resp)
Crufomate TWA 5 mg/m3
Cyanamide TWA 2 mg/m3
Cyanogen TWA 10 ppm (20 mg/m3)
Cyanogen chlorideC 0.3 ppm (0.6 mg/m3)
Cyclohexanol TWA 50 ppm (200 mg/m3) [skin]
Cyclohexanone TWA 25 ppm (100 mg/m3) [skin]
Cyclohexylamine TWA 10 ppm (40 mg/m3)
Cyclonite TWA 1.5 mg/m3 [skin]
Cyclopentane TWA 600 ppm (1720 mg/m3)
Cyhexatin TWA 5 mg/m3
Decaborane TWA 0.3 mg/m3 (0.05 ppm)
ST 0.9 mg/m3 (0.15 ppm) [skin]
Diazinon TWA 0.1 mg/m3 [skin]
2-N-Dibutylaminoethanol TWA 2 ppm (14 mg/m3)
Dibutyl phosphateTWA 1 ppm (5 mg/m3)
ST 2 ppm (10 mg/m3)
DichloroacetyleneC 0.1 ppm (0.4 mg/m3)
p-DichlorobenzeneTWA 75 ppm (450 mg/m3)
ST 110 ppm (675 mg/m3)
1,3-Dichloro-5,5-dimethylhydantoin TWA 0.2 mg/m3
ST 0.4 mg/m3
Dichloroethyl ether TWA 5 ppm (30 mg/m3)
ST 10 ppm (60 mg/m3) [skin]
DichloromonofluoromethaneTWA 10 ppm (40 mg/m3)
1,1-Dichloro-1-nitroethaneTWA 2 ppm (10 mg/m3)
1,3-Dichloropropene TWA 1 ppm (5 mg/m3) [skin]
2,2-Dichloropropionic acidTWA 1 ppm (6 mg/m3)
Dicrotophos TWA 0.25 mg/m3 [skin]
DicyclopentadieneTWA 5 ppm (30 mg/m3)
Dicyclopentadienyl iron TWA 10 mg/m3 (total)
TWA 5 mg/m3 (resp)
Diethanolamine TWA 3 ppm (15 mg/m3)
Diethylamine TWA 10 ppm (30 mg/m3)
ST 25 ppm (75 mg/m3)
Diethylenetriamine TWA 1 ppm (4 mg/m3)
Diethyl ketone TWA 200 ppm (705 mg/m3)
Diethyl phthalateTWA 5 mg/m3
Diglycidyl etherTWA 0.1 ppm (0.5 mg/m3)
Diisobutyl ketoneTWA 25 ppm (150 mg/m3)
N,N-Dimethylaniline TWA 5 ppm (25 mg/m3)
ST 10 ppm (50 mg/m3) [skin]
Dimethyl-1,2-dibromo-2,2-dichlorethyl phosphateTWA 3 mg/m3 [skin]
Dimethyl sulfateTWA 0.1 ppm (0.5 mg/m3) [skin]
Dinitolmide TWA 5 mg/m3
Di-sec octyl phthalate TWA 5 mg/m3
ST 10 mg/m3
Dioxane TWA 25 ppm (90 mg/m3) [skin]
Dioxathion TWA 0.2 mg/m3 [skin]
Diphenylamine TWA 10 mg/m3
Dipropylene glycol methyl etherTWA 100 ppm (600 mg/m3)
ST 150 ppm (900 mg/m3) [skin]
Dipropyl ketone TWA 50 ppm (235 mg/m3)
Diquat (Diquat dibromide)TWA 0.5 mg/m3
Disulfiram TWA 2 mg/m3
Disulfoton TWA 0.1 mg/m3 [skin]
2,6-Di-tert-butyl-p-cresolTWA 10 mg/m3
Diuron TWA 10 mg/m3
Divinyl benzene TWA 10 ppm (50 mg/m3)
Emery TWA 10 mg/m3 (total)
TWA 5 mg/m3 (resp)
Endosulfan TWA 0.1 mg/m3 [skin]
Epichlorohydrin TWA 2 ppm (8 mg/m3) [skin]
Ethanolamine TWA 3 ppm (8 mg/m3)
ST 6 ppm (15 mg/m3)
Ethion TWA 0.4 mg/m3 [skin]
Ethyl acrylate TWA 5 ppm (20 mg/m3)
ST 25 ppm (100 mg/m3) [skin]
Ethyl benzene TWA 100 ppm (435 mg/m3)
ST 125 ppm (545 mg/m3)
Ethyl bromide TWA 200 ppm (890 mg/m3)
ST 250 ppm (1110 mg/m3)
Ethylene chlorohydrin C 1 ppm (3 mg/m3) [skin]
Ethylene dichloride TWA 1 ppm (4 mg/m3)
ST 2 ppm (8 mg/m3)
Ethylene glycol C 50 ppm (125 mg/m3)
Ethylene glycol dinitrateST 0.1 mg/m3 [skin]
Ethyl ether TWA 400 ppm (1200 mg/m3)
ST 500 ppm (1500 mg/m3)
Ethylidene norbornene C 5 ppm (25 mg/m3)
Ethyl mercaptan TWA 0.5 ppm (1 mg/m3)
N-EthylmorpholineTWA 5 ppm (23 mg/m3) [skin]
Ethyl silicate TWA 10 ppm (85 mg/m3)
Fenamiphos TWA 0.1 mg/m3 [skin]
Fensulfothion TWA 0.1 mg/m3
Fenthion TWA 0.2 mg/m3 [skin]
Ferbam TWA 10 mg/m3
Ferrovanadium dust TWA 1 mg/m3
ST 3 mg/m3
Fluorotrichloromethane C 1000 ppm (5600 mg/m3)
Fonofos TWA 0.1 mg/m3 [skin]
Formamide TWA 20 ppm (30 mg/m3)
ST 30 ppm (45 mg/m3)
Furfural TWA 2 ppm (8 mg/m3) [skin]
Furfuryl alcoholTWA 10 ppm (40 mg/m3)
ST 15 ppm (60 mg/m3) [skin]
Gasoline TWA 300 ppm (900 mg/m3)
ST 500 ppm (1500 mg/m3)
Germanium tetrahydride TWA 0.2 ppm (0.6 mg/m3)
Glutaraldehyde C 0.2 ppm (0.8 mg/m3)
Glycerin (mist) TWA 10 mg/m3 (total)
TWA 5 mg/m3 (resp)
Glycidol TWA 25 ppm (75 mg/m3)
Graphite (natural) TWA 2.5 mg/m3 (resp)
Graphite (synthetic) TWA 10 mg/m3 (total)
TWA 5 mg/m3 (resp)
n-Heptane TWA 400 ppm (1600 mg/m3)
ST 500 ppm (2000 mg/m3)
Hexachlorobutadiene TWA 0.02 ppm (0.24 mg/m3)
HexachlorocyclopentadieneTWA 0.01 ppm (0.1 mg/m3)
HexafluoroacetoneTWA 0.1 ppm (0.7 mg/m3) [skin]
n-Hexane TWA 50 ppm (180 mg/m3)
Hexane isomers (except n-Hexane) TWA 500 ppm (1800 mg/m3)
ST 1000 ppm (3600 mg/m3)
2-Hexanone TWA 5 ppm (20 mg/m3)
Hexone TWA 50 ppm (205 mg/m3)
ST 75 ppm (300 mg/m3)
Hexylene glycol C 25 ppm (125 mg/m3)
Hydrazine TWA 0.1 ppm (0.1 mg/m3) [skin]
Hydrogenated terphenyls TWA 0.5 ppm (5 mg/m3)
Hydrogen bromideC 3 ppm (10 mg/m3)
Hydrogen cyanideST 4.7 ppm (5 mg/m3) [skin]
Hydrogen fluoride (as F) TWA 3 ppm
ST 6 ppm
Hydrogen sulfideTWA 10 ppm (14 mg/m3)
ST 15 ppm (21 mg/m3)
2-Hydroxypropyl acrylate TWA 0.5 ppm (3 mg/m3) [skin]
Indene TWA 10 ppm (45 mg/m3)
Indium TWA 0.1 mg/m3
Iodoform TWA 0.6 ppm (10 mg/m3)
Iron pentacarbonyl (as Fe)TWA 0.1 ppm (0.8 mg/m3)
ST 0.2 ppm (1.6 mg/m3)
Iron salts (soluble, as Fe) TWA 1 mg/m3
Isoamyl alcohol (primary & secondary) TWA 100 ppm (360 mg/m3)
ST 125 ppm (450 mg/m3)
Isobutane TWA 800 ppm (1900 mg/m3)
Isobutyl alcoholTWA 50 ppm (150 mg/m3)
Isooctyl alcoholTWA 50 ppm (270 mg/m3) [skin]
Isophorone TWA 4 ppm (23 mg/m3)
Isophorone diisocyanate TWA 0.005 ppm
ST 0.02 ppm [skin]
2-Isopropoxyethanol TWA 25 ppm (105 mg/m3)
Isopropyl acetateTWA 250 ppm (950 mg/m3)
ST 310 ppm (1185 mg/m3)
Isopropyl alcoholTWA 400 ppm (980 mg/m3)
ST 500 ppm (1225 mg/m3)
Isopropylamine TWA 5 ppm (12 mg/m3)
ST 10 ppm (24 mg/m3)
N-Isopropylaniline TWA 2 ppm (10 mg/m3) [skin]
Isopropyl glycidyl ether TWA 50 ppm (240 mg/m3)
ST 75 ppm (360 mg/m3)
Kaolin TWA 10 mg/m3 (total)
TWA 5 mg/m3 (resp)
Ketene TWA 0.5 ppm (0.9 mg/m3)
ST 1.5 ppm (3 mg/m3)
Magnesium oxide fume TWA 10 mg/m3
Malathion TWA 10 mg/m3 [skin]
Manganese compounds and fume (as Mn) Compounds:
C 5 mg/m3

Fume:
TWA 1 mg/m3
ST 3 mg/m3
Manganese cyclopentadienyl tricarbonyl (as Mn) TWA 0.1 mg/m3 [skin]
Manganese tetroxide (as Mn) TWA 1 mg/m3
Mercury compounds, as Hg [except(organo) alkyls]
Hg Vapor
TWA 0.05 mg/m3 [skin]
Non-alkyl compounds
C 0.1 mg/m3 [skin]
Mercury (organo) alkyl compounds (as Hg) TWA 0.01 mg/m3
ST 0.03 mg/m3 [skin]
Mesityl oxide TWA 15 ppm (60 mg/m3)
ST 25 ppm (100 mg/m3)
Methacrylic acidTWA 20 ppm (70 mg/m3) [skin]
Methomyl TWA 2.5 mg/m3
Methoxychlor TWA 10 mg/m3
4-Methoxyphenol TWA 5 mg/m3
Methyl acetate TWA 200 ppm (610 mg/m3)
ST 250 ppm (760 mg/m3)
Methyl acetylene-propadiene mixtureTWA 1000 ppm (1800 mg/m3)
ST 1250 ppm (2250 mg/m3)
Methylacrylonitrile TWA 1 ppm (3 mg/m3) [skin]
Methyl alcohol TWA 200 ppm (260 mg/m3)
ST 250 ppm (325 mg/m3) [skin]
Methyl bromide TWA 5 ppm (20 mg/m3) [skin]
Methyl chloride TWA 50 ppm (105 mg/m3)
ST 100 ppm (210 mg/m3)
Methyl chloroformTWA 350 ppm (1900 mg/m3)
ST 450 ppm (2450 mg/m3)
Methyl-2-cyanoacrylate TWA 2 ppm (8 mg/m3)
ST 4 ppm (16 mg/m3)
MethylcyclohexaneTWA 400 ppm (1600 mg/m3)
Methylcyclohexanol TWA 50 ppm (235 mg/m3)
o-Methylcyclohexanone TWA 50 ppm (230 mg/m3)
ST 75 ppm (345 mg/m3) [skin]
Methyl cyclopentadienyl manganese tricarbonyl (as Mn) TWA 0.2 mg/m3 [skin]
Methyl demeton TWA 0.5 mg/m3 [skin]
4,4'-Methylenebis(2-chloroaniline) TWA 0.02 ppm (0.22 mg/m3) [skin]
Methylene bis(4-cyclo-hexylisocyanate) C 0.01 ppm (0.11 mg/m3) [skin]
Methyl ethyl ketone peroxide C 0.7 ppm (5 mg/m3)
Methyl formate TWA 100 ppm (250 mg/m3)
ST 150 ppm (375 mg/m3)
Methyl iodide TWA 2 ppm (10 mg/m3) [skin]
Methyl isoamyl ketone TWA 50 ppm (240 mg/m3)
Methyl isobutyl carbinol TWA 25 ppm (100 mg/m3)
ST 40 ppm (165 mg/m3) [skin]
Methyl isopropyl ketone TWA 200 ppm (705 mg/m3)
Methyl mercaptanTWA 0.5 ppm (1 mg/m3)
Methyl parathionTWA 0.2 mg/m3 [skin]
Methyl silicate TWA 1 ppm (6 mg/m3)
alpha-Methyl styreneTWA 50 ppm (240 mg/m3)
ST 100 ppm (485 mg/m3)
Metribuzin TWA 5 mg/m3
Mica TWA 3 mg/m3 (resp)
Molybdenum (insoluble compounds, as Mo) TWA 10 mg/m3
Monocrotophos TWA 0.25 mg/m3
Monomethyl aniline TWA 0.5 ppm (2 mg/m3) [skin]
Morpholine TWA 20 ppm (70 mg/m3)
ST 30 ppm (105 mg/m3) [skin]
Naphthalene TWA 10 ppm (50 mg/m3)
ST 15 ppm (75 mg/m3)
Nickel metal & other compounds (as Ni)
Metal & insoluble compounds
TWA 1 mg/m3
Soluble compounds
TWA 0.1 mg/m3
Nitric acid TWA 2 ppm (5 mg/m3)
ST 4 ppm (10 mg/m3)
p-Nitroaniline TWA 3 mg/m3 [skin]
Nitrogen dioxideST 1 ppm (1.8 mg/m3)
Nitroglycerine ST 0.1 mg/m3 [skin]
2-Nitropropane TWA 10 ppm (35 mg/m3)
Nitrotoluene (o-, m-, p-isomers) TWA 2 ppm (11 mg/m3) [skin]
Nonane TWA 200 ppm (1050 mg/m3)
Octachloronaphthalene TWA 0.1 mg/m3
ST 0.3 mg/m3 [skin]
Octane TWA 300 ppm (1450 mg/m3)
ST 375 ppm (1800 mg/m3)
Osmium tetroxide (as Os) TWA 0.002 mg/m3 (0.0002 ppm)
ST 0.006 mg/m3 (0.0006 ppm)
Oxalic acid TWA 1 mg/m3
ST 2 mg/m3
Oxygen difluorideC 0.05 ppm (0.1 mg/m3)
Ozone TWA 0.1 ppm (0.2 mg/m3)
ST 0.3 ppm (0.6 mg/m3)
Paraffin wax fumeTWA 2 mg/m3
Paraquat TWA 0.1 mg/m3 (resp) [skin]
Pentaborane TWA 0.005 ppm (0.01 mg/m3)
ST 0.015 ppm (0.03 mg/m3)
Pentaerythritol TWA 10 mg/m3 (total)
TWA 5 mg/m3 (resp)
n-Pentane TWA 600 ppm (1800 mg/m3)
ST 750 ppm (2250 mg/m3)
2-Pentanone TWA 200 ppm (700 mg/m3)
ST 250 ppm (875 mg/m3)
Perchloryl fluoride TWA 3 ppm (14 mg/m3)
ST 6 ppm (28 mg/m3)
Petroleum distillates (naphtha)TWA 400 ppm (1600 mg/m3)
Phenothiazine TWA 5 mg/m3 [skin]
Phenyl glycidyl ether TWA 1 ppm (6 mg/m3)
Phenylhydrazine TWA 5 ppm (20 mg/m3)
ST 10 ppm (45 mg/m3) [skin]
Phenylphosphine C 0.05 ppm (0.25 mg/m3)
Phorate TWA 0.05 mg/m3
ST 0.2 mg/m3 [skin]
Phosdrin TWA 0.01 ppm (0.1 mg/m3)
ST 0.03 ppm (0.3 mg/m3) [skin]
Phosphine TWA 0.3 ppm (0.4 mg/m3)
ST 1 ppm (1 mg/m3)
Phosphoric acid TWA 1 mg/m3
ST 3 mg/m3
Phosphorus oxychloride TWA 0.1 ppm (0.6 mg/m3)
Phosphorus pentasulfide TWA 1 mg/m3
ST 3 mg/m3
Phosphorus trichloride TWA 0.2 ppm (1.5 mg/m3)
ST 0.5 ppm (3 mg/m3)
Phthalic anhydride TWA 6 mg/m3 (1 ppm)
m-Phthalodinitrile TWA 5 mg/m3
Picloram TWA 10 mg/m3 (total)
TWA 5 mg/m3 (resp)
Piperazine dihydrochlorideTWA 5 mg/m3
Platinum metal (as Pt) TWA 1 mg/m3
Portland cement TWA 10 mg/m3 (total)
TWA 5 mg/m3 (resp)
Potassium hydroxide TWA 2 mg/m3
Propargyl alcoholTWA 1 ppm (2 mg/m3) [skin]
Propionic acid TWA 10 ppm (30 mg/m3)
Propoxur TWA 0.5 mg/m3
n-Propyl acetateTWA 200 ppm (840 mg/m3)
ST 250 ppm (1050 mg/m3)
n-Propyl alcoholTWA 200 ppm (500 mg/m3)
ST 250 ppm (625 mg/m3)
Propylene dichloride TWA 75 ppm (350 mg/m3)
ST 110 ppm (510 mg/m3)
Propylene glycol dinitrateTWA 0.05 ppm (0.3 mg/m3)
Propylene glycol monomethyl ether TWA 100 ppm (360 mg/m3)
ST 150 ppm (540 mg/m3)
Propylene oxide TWA 20 ppm (50 mg/m3)
n-Propyl nitrateTWA 25 ppm (105 mg/m3)
ST 40 ppm (170 mg/m3)
Resorcinol TWA 10 ppm (45 mg/m3)
ST 20 ppm (90 mg/m3)
Ronnel TWA 10 mg/m3
Rosin core solder, pyrolysis products (as formaldehyde) TWA 0.1 mg/m3
Rouge TWA 10 mg/m3 (total)
TWA 5 mg/m3 (resp)
Silica, amorphousTWA 6 mg/m3
TWA 0.1 mg/m3 (fused)
Silica, crystalline (as respirable dust) TWA 0.05 mg/m3 (cristobalite)
TWA 0.05 mg/m3 (tridymite)
TWA 0.1 mg/m3 (quartz)
TWA 0.1 mg/m3 (tripoli)
Silicon TWA 10 mg/m3 (total)
TWA 5 mg/m3 (resp)
Silicon carbide TWA 10 mg/m3 (total)
TWA 5 mg/m3 (resp)
Silicon tetrahydride TWA 5 ppm (7 mg/m3)
Soapstone TWA 6 mg/m3 (total)
TWA 3 mg/m3 (resp)
Sodium azide C 0.1 ppm (as HN3) [skin]
C 0.3 mg/m3 (as NaN3) [skin]
Sodium bisulfiteTWA 5 mg/m3
Sodium fluoroacetate TWA 0.05 mg/m3
ST 0.15 mg/m3 [skin]
Sodium hydroxideC 2 mg/m3
Sodium metabisulfite TWA 5 mg/m3
Stoddard solventTWA 525 mg/m3 (100 ppm)
Styrene TWA 50 ppm (215 mg/m3)
ST 100 ppm (425 mg/m3)
Subtilisins ST 0.00006 mg/m3 [60-minute]
Sulfur dioxide TWA 2 ppm (5 mg/m3)
ST 5 ppm (13 mg/m3)
Sulfur monochloride C 1 ppm (6 mg/m3)
Sulfur pentafluoride C 0.01 ppm (0.1 mg/m3)
Sulfur tetrafluoride C 0.1 ppm (0.4 mg/m3)
Sulfuryl fluorideTWA 5 ppm (20 mg/m3)
ST 10 ppm (40 mg/m3)
Sulprofos TWA 1 mg/m3
Talc TWA 2 mg/m3 (resp)
Temephos TWA 10 mg/m3 (total)
TWA 5 mg/m3 (resp)
Terphenyl (o-, m-, p-isomers) C 5 mg/m3 (0.5 ppm)
1,1,2,2-TetrachloroethaneTWA 1 ppm (7 mg/m3) [skin]
Tetrachloroethylene TWA 25 ppm (170 mg/m3)
Tetrahydrofuran TWA 200 ppm (590 mg/m3)
ST 250 ppm (735 mg/m3)
Tetrasodium pyrophosphateTWA 5 mg/m3
4,4'-Thiobis(6-tert-butyl-m-cresol)TWA 10 mg/m3 (total)
TWA 5 mg/m3 (resp)
Thioglycolic acidTWA 1 ppm (4 mg/m3) [skin]
Thionyl chlorideC 1 ppm (5 mg/m3)
Tin (organic compounds, as Sn)TWA 0.1 mg/m3 [skin]
Tin(II) oxide (as Sn) TWA 2 mg/m3
Tin(IV) oxide (as Sn) TWA 2 mg/m3
Titanium dioxideTWA 10 mg/m3
Toluene TWA 100 ppm (375 mg/m3)
ST 150 ppm (560 mg/m3)
Toluene-2,4-diisocyanate TWA 0.005 ppm (0.04 mg/m3)
ST 0.02 ppm (0.15 mg/m3)
m-Toluidine TWA 2 ppm (9 mg/m3) [skin]
p-Toluidine TWA 2 ppm (9 mg/m3) [skin]
Tributyl phosphate TWA 0.2 ppm (2.5 mg/m3)
Trichloroacetic acid TWA 1 ppm (7 mg/m3)
1,2,4-Trichlorobenzene C 5 ppm (40 mg/m3)
TrichloroethyleneTWA 50 ppm (270 mg/m3)
ST 200 ppm (1080 mg/m3)
1,2,3-Trichloropropane TWA 10 ppm (60 mg/m3)
1,1,2-Trichloro-1,2,2-trifluoroethaneTWA 1000 ppm (7600 mg/m3)
ST 1250 ppm (9500 mg/m3)
Triethylamine TWA 10 ppm (40 mg/m3)
ST 15 ppm (60 mg/m3)
Trimellitic anhydride TWA 0.005 ppm (0.04 mg/m3)
Trimethylamine TWA 10 ppm (24 mg/m3)
ST 15 ppm (36 mg/m3)
1,2,3-Trimethylbenzene TWA 25 ppm (125 mg/m3)
1,2,4-Trimethylbenzene TWA 25 ppm (125 mg/m3)
1,3,5-Trimethylbenzene TWA 25 ppm (125 mg/m3)
Trimethyl phosphite TWA 2 ppm (10 mg/m3)
2,4,6-Trinitrotoluene TWA 0.5 mg/m3 [skin]
Triorthocresyl phosphate TWA 0.1 mg/m3 [skin]
Triphenylamine TWA 5 mg/m3
Tungsten (insoluble compounds, as W)TWA 5 mg/m3
ST 10 mg/m3
Tungsten (soluble compounds, as W) TWA 1 mg/m3
ST 3 mg/m3
Tungsten carbide (cemented) TWA 5 mg/m3 (as W)
ST 10 mg/m3 (as W)
TWA 0.05 mg/m3 (as Co)
TWA 1 mg/m3 (as Ni)
Uranium (insoluble compounds, as U)TWA 0.2 mg/m3
ST 0.6 mg/m3
n-Valeraldehyde TWA 50 ppm (175 mg/m3)
Vanadium dust TWA 0.05 mg V2O5/m3 (resp)
Vanadium fume C 0.05 mg V2O5/m3
Vinyl acetate TWA 10 ppm (30 mg/m3)
ST 20 ppm (60 mg/m3)
Vinyl bromide TWA 5 ppm (20 mg/m3)
Vinyl cyclohexene dioxideTWA 10 ppm (60 mg/m3) [skin]
Vinylidene chloride TWA 1 ppm (4 mg/m3)
VM & P Naphtha TWA 1350 mg/m3 (300 ppm)
ST 1800 mg/m3 (400 ppm)
Welding fumes TWA 5 mg/m3
Wood dust (all wood dusts except Western red cedar)TWA 5 mg/m3
ST 10 mg/m3
Wood dust (Western red cedar) TWA 2.5 mg/m3
Xylene (o-, m-, p-isomers)TWA 100 ppm (435 mg/m3)
ST 150 ppm (655 mg/m3)
m-Xylene alpha, alpha'-diamine C 0.1 mg/m3 [skin]
Xylidine TWA 2 ppm (10 mg/m3) [skin]
Zinc chloride fume TWA 1 mg/m3
ST 2 mg/m3
Zinc oxide TWA 5 mg/m3 (fume)
ST 10 mg/m3 (fume)
TWA 10 mg/m3 (total dust)
TWA 5 mg/m3 (resp dust)
Zinc stearate TWA 10 mg/m3 (total)
TWA 5 mg/m3 (resp)
Zirconium compounds (as Zr) TWA 5 mg/m3
ST 10 mg/m3

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This page was last updated on July 28, 2005

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