Annex 11 of NR15 – Tolerance Limits for Chemical Agents and Inspections in the Workplace

1. In activities or operations where workers are exposed to chemical agents, the characterization of hazards will occur when the exposure limits listed in Table No. 1 of this Annex are exceeded.

2. All values set forth in Table No. 1 – Tolerance Limits Table are valid for absorption only through the respiratory route.

3. All values set forth in Table No. 1 as “Simple Asphyxiants” indicate that in the presence of these substances in the workplace, the minimum oxygen concentration must be 18 (eighteen) percent by volume. Situations where the oxygen concentration is below this value will be considered a serious and imminent risk.

4. The “CEILING VALUE” column lists the chemical agents whose tolerance limits must not be exceeded at any time during the workday.

5. The “ALSO ABSORBED THROUGH THE SKIN” column lists the chemical agents that can be absorbed through the skin, thereby requiring the use of suitable gloves during handling, in addition to the necessary PPE to protect other parts of the body.

6. The assessment of chemical agent concentrations through instantaneous sampling methods, whether direct-reading or not, must be carried out with at least 10 (ten) samples at each point – at the worker’s respiratory level. There must be a minimum interval of 20 (twenty) minutes between each sampling.

7. Each of the concentrations obtained in these samples must not exceed the values obtained in the following equation, otherwise, it will be considered a situation of serious and imminent risk.

    • Maximum Value = T.L. x D.F.
      • Where:
      • T.L. = tolerance limit for the chemical agent, according to Table No. 1.
      • D.F. = deviation factor, as defined in Table No. 2.

    Table 2

    T.L. (ppm or mg/m³)D.F.
    0 to 13
    1 to 102
    10 to 1001.5
    100 to 10001.25
    above 10001.1

    8. The tolerance limit will be considered exceeded when the arithmetic mean of the concentrations exceeds the values set in Table No. 1.

    9. For chemical agents that have a “CEILING VALUE” indicated in Table No. 1 (Tolerance Limits Table), the tolerance limit will be considered exceeded when any of the concentrations obtained in the samples exceed the values set in the same table.

    10. The tolerance limits set in Table No. 1 are valid for workweeks of up to 48 (forty-eight) hours.

      10.1 For workweeks exceeding 48 (forty-eight) hours, the provisions of Article 60 of the CLT must be followed.

      Table 1 – Table of Tolerance Limits

      CHEMICAL AGENTSCeiling LimitAbsoroption through skinUp to 48 hours per weekUnhealthiness degree to be considered in characterization
      Acetaldehyde  78140maximum
      Cellosolve acetate +78420medium
      Ethylene glycol monoethyl ether acetate (see Cellosolve acetate)  
      Ethyl acetate  3101090minimum
      Ethyl 2-ethoxy ethyl (see Cellosolve ethyl)  
      Acetylene  Asphyxiantsimple
      Acetone  7801870minimum
      Acetonitrile  3055maximum
      Acetic acid  820medium
      Hydrogen cyanide +89maximum
      Hydrochloric acid+ 45,5maximum
      Chromic acid (mist)  0,04maximum
      Ethanoic acid (see Acetic acid)  
      Hydrofluoric acid  2,51,5maximum
      Formic acid  47medium
      Methanoic acid (see Formic acid)  
      Methyl acrylate +827maximum
      Acrylonitrile +1635maximum
      Iso-amyl alcohol  78280minimum
      N-Butyl alcohol++40115maximum
      Isobutyl alcohol  40115medium
      Sec-butyl alcohol (2-butanol)  115350medium
      Tert-butyl alcohol  78235medium
      Ethyl alcohol  7801480minimum
      Furfuryl alcohol +415,5medium
      Methyl amyl alcohol (see Methyl isobutyl carbinol)  
      Methyl alcohol +156200maximum
      N-Propyl alcohol +156390medium
      Isopropyl alcohol +310765medium
      Acetic aldehyde (see Acetaldehyde)  
      Formic aldehyde (see Formaldehyde)  
      Ammonia  2014medium
      Anhydrous sulfur (see Sulfur dioxide)  
      Aniline +415maximum
      Argon  Asphyxiantsimple
      Arsine  0,040,16maximum
      Ethyl bromide  156695maximum
      Methyl bromide +1247maximum
      Bromine  0,080,6maximum
      Bromoethane (see Ethyl bromide)  
      Bromoform +0,44medium
      Bromomethane (see Methyl bromide)  
      1,3 Butadiene  7801720medium
      n-Butane  4701090medium
      n-Butane (see N-butyl alcohol)  
      sec-Butanol (see Sec-butyl alcohol)  
      Butanone (see Methyl ethyl ketone)  
      1-Butanethiol (see Butyl mercaptan)  
      Cellosolve butyl +39190medium
      n-Butil mercaptana  0,41,2medium
      2-Butoxyethanol (see Cellosolve butyl)   
      Cellosolve (see 2-ethoxy ethanol)  
      Lead  0,1maximum
      Methyl cyanide (see Acetonitrile)  
      Vinyl cyanide (see Acrylonitrile)  
      Cyanogen  816maximum
      Cyclohexane  235820medium
      Cyclohexanol  40160maximum
      Cyclohexylamine +832maximum
      Carbonyl chloride (see Phosgene)  
      Ethyl chloride  7802030medium
      Phenyl chloride (see Chloro benzene)  
      Methyl chloride  78165maximum
      Methylene chloride  156560maximum
      Vinyl chloride+ 156398maximum
      Vinylidene chloride  831maximum
      Chlorine  0,82,3maximum
      Chlorobenzene  59275medium
      Clorobromomethane  156820maximum
      Chloroethane (see Ethyl chloride)  
      Chloroethyl (see Vinyl chloride)  
      (Freon 22)
      Chloroform  2094maximum
      1-chloro-1-nitropropane  1678maximum
      Chloroprene +2070maximum
      Cumene +39190maximum
      Decaborane +0,040,25maximum
      Demeton +0,0080,08maximum
      Diamine (see Hydrazine)  
      Diborane  0,080,08maximum
      1,2-Dibramoetano +16110medium
      o-Dichlorobenzene  39235maximum
      Dichlorodifluoromethane (Freon 12)+ 7803860minimum
      1,1 Dichloroethane  156640medium
      1,2 Dichloroethane  39156maximum
      Dichloroethylene (see Vinylidene chloride)
      1,2 Dichloroethylene  155615medium
      Dichloromethane (see Methyl chloride)  
      1,1 Dichloro-1-nitroethane+ 847maximum
      1.2 Dichloropropane  59275maximum
      Dichlorotetrafluoroethane (Freon 114)  7805460minimum
      Diethylamine  2059medium
      Diethyl ether (see Ethyl ether)  
      2,4 Toluene diisocyanate (TDI)+ 0,0160,11maximum
      Diisopropylamine +416maximum
      Dimethylacetamide +828maximum
      Dimethylamine  814medium
      Dimethylformamide  824medium
      l, l Dimethyl hydrazine +0,40,8maximum
      Carbon dioxide  39007020minimum
      Chlorine dioxide  0,080,25maximum
      Sulphur dioxide  410maximum
      Nitrogen dioxide+ 47maximum
      Carbon disulfide +1647maximum
      Stibnite  0,080,4maximum
      Styrene  78328medium
      Ethanol (see Acetaldehyde)  ___
      Ethane  Asphyxiantsimples_
      Ethanol (see Ethyl)  ___
      Ethanethiol (see Ethyl mercaptan)  ___
      Dichloroethyl ether +424maximum
      Ethyl ether  310940medium
      Ethylene glycol
      monobutyl ether (see Cellosolve buthyl)
      Ethylene glycol monoethyl ether (see Cellosolve)  ___
      Ethylene glycol monomethyl ether (see Cellosolve methyl)  ___
      Ethylamine  814maximum
      Ethylbenzene  78340medium
      Ethylene  Asphyxiantsimples_
      Ethyleneimine +0,40,8maximum
      Ethyl mercaptan  0,40,8medium
      n-Ethyl morpholine +1674medium
      2-Ethoxyethanol +78290medium
      Phenol +415maximum
      (Freon 11)
      Formaldehyde (formalin)+ 1,62,3maximum
      Phosphine  0,230,3maximum
      Fosgênio  0,080,3maximum
      Freon 11 (see Fluortrichloromethano)  ___
      Freon 12 (see Dichlorodifluoromethane)  ___
      Freon 22 (see Chlorodifluoromethane)  ___
      Freon 113 (see 1,1,2, 1,2,2-trichlorotrifluoroethane)  ___
      Freon 114 (see Dichlrorotetrafluorethane)  ___
      Ammonia gas (see
      Carbonic gas (see Carbon dioxide)  ___
      Hydrocyanic gas (see
      Hydrocyanic acid)
      Chlorine gas (see Hydrochloric acid)  ___
      Sulfide gas  812maximum
      Helium  Asphyxiantsimples_
      Hydrazine +0,080,08maximum
      Antimony hydride antimony (see Stibnite)  ___
      Hydrogen  Asphyxiantsimples_
      Isobutanol (see Isobutyl alcohol)  ___
      Isopropylamine  49,5medium
      Isopropyl benzene (see Cumene)  ___
      Mercury (all except organic forms)  _0,04maximum
      Methyl methacrylate  78320minimum
      Methane  Asphyxiantsimples_
      Methanol (see Methyl alcohol)  ___
      Methylamine  89,5maximum
      Cellosolve methyl +2060maximum
      Methyl cyclohexanol  39180medium
      Methyl chloroform  2751480medium
      Methyl demeton +_0,4maximum
      Methyl ethyl ketone  155460medium
      Methyl isobutylcarbinol +2078maximum
      Methyl mercaptan (methanethiol)  0,040,8medium
      2-Methoxy ethanol (see Cellosolve methyl)  ___
      Monomethyl hydrazine++0,160,27maximum
      Carbon monoxide  3943maximum
      Carbon black (1)   3,5maximum
      Neon  Asphyxiantsimples_
      Nickel carbonyl (Nickel tetracarbonyl)  0,040,28maximum
      N-propyl nitrate  2085maximum
      Nitroethane  78245medium
      Nitromethane  78195maximum
      1 – Nitropropane  2070medium
      2 – Nitropropane  2070medium
      Ethylene oxide  3970maximo
      Nitric oxide (NO)  2023maximum
      Nitrous oxide (N2O)  Asphyxiantsimples
      Ozone  0,080,16maximum
      Pentaborane  0,0040,008maximum
      n-Pentane +4701400minimum
      Perchloroethylene  78525medium
      Pyridine  412medium
      n-Propane  Asphyxiantsimples
      n-Propanol (see n-Propyl alcohol)  
      iso-Propanol (see Isopropyl alcohol)  
      Propanone (see Acetone)  
      Propylene  Asphyxiantsimples
      Propylene imine +1,64maximum
      Dimethyl sulphate++0,080,4maximum
      Hydrogene sulphide (see Sulfhydric gas)  
      Systox (see Demeton)  
      1,1,2,2,Tetrabromoethane  0,811medium
      Carbon tetrachloride +850maximum
      Tetrachloroethane +427maximum
      Tetrachloroethylene (see Perchloroethylene)  
      Tetrahydrofuran  156460maximum
      Toluene +78290medium
      Tolueno-2,4-diisocyanate (TDI) (see 2,4 toluene diisocyanate)  
      Tribromomethane (see Bromoform)  
      Vinyl trichloride (see 1,1,2 trichloroethane)  
      1,1,1 Trichloroethane (see Methyl chloroform)  
      1,1,2 Trichloroethane +835medium
      Trichloroethylene  78420maximum
      Trichloromethane (see Chloroform)  
      1,2,3 Trichloropropane  40235maximum
      1,1,2 Trichloro-1,2,2 trifluoroethane (Freon 113)  7805930medium
      Triethylamine  2078maximum
      Trifluoro monobromo
      Vinyl benzene (see Sytrene)  
      Xylene (Xylol)  78340medium

      * ppm – parts of vapor or gas per million parts of contaminated air.

      ** mg/m³ – milligrams per cubic meter of air.