Serial No.

Substance

Permissible limits of exposure

Time-weighted average concentration (8 hrs)

Short-term exposure limit (15 min)*

ppm

mg/m^{3 **}

ppm

mg/m^{3 **}

1.       

Acetaldehyde

100

180

150

270

2.       

Acetic acid

10

25

15

37

3.       

Acetone

750

1780

1000

2375

4.       

Acrclein

0.1

0.25

0.3

0.8

5.       

Acrylonitrile-Skin

2

4.5

-

-

6.       

Aldrin-skin

-

0.25

-

-

7.       

Allychloride

1

3

2

6

8.       

Ammonia

25

18

35

27

9.       

Aniline-Skin

2

10

-

-

10.    

Anisidine (o-,pisomers) Skin

0.1

0.5

-

-

11.    

Arsenic & soluble compounds (as As)

-

0.2

-

-

12.    

Benzene (S.C.)

10

30

-

-

13.    

Beryllium & compound (as Be) (S.C.)

-

0.002

-

-

14.    

Boron trifluoride-C

1

3

-

-

15.    

Bromine

0.1

0.7

0.3

2

16.    

Butane

800

1900

-

-

17.    

2-Butanone (Methyl ethyl Ketone-MEK)

200

590

300

835

18.    

n-Butylacetate 150

710

200

950

-

19.    

n-Butyle alcohol-Skin-C

50

150

-

-

20.    

Sec/tert. Butylacetate

200

950

-

-

21.    

Butyl mercaptan

0.5

1.5

-

-

22.    

Cadmium Dusts and salts (as Cd)

-

0.05

-

-

23.    

Calcium oxide

-

2

-

-

24.    

Carbaryl (Sevin)

-

5

-

-

25.    

Carbofuran (Furadan)

-

0.1

-

-

26.    

Carbon disulphade-Skin

10

30

-

-

27.    

Carbon monoxide

50

55

400

440

28.    

Carbon to trachloride-Skin (S.C.)

5

30

-

-

29.    

Chlorodene-Skin

-

0.5

-

-

30.    

Chlorine

1

3

3

9

31.    

Chlorobenzene (Monochlorobenzene)

75

350

-

-

32.    

Chloroform (S.C.)

10

50

-

-

33.    

bis (Chloromethyl) ether (RC.)

0.001

0.005

-

-

34.    

Chromic acid and chromates (as Cr)

-

0.05

-

-

35.    

Chromous salts (as Cr)

-

0.05

-

-

36.    

Copper Fume

-

0.2

-

-

37.    

Cotton dust, raw*

-

0.2*

-

-

38.    

Crosol, all isomers-Skin

5

22

-

-

39.    

Cyanides (as CN)-Skin

-

5

-

-

40.    

Cyanogen

-

10

20

-

41.    

DDT (Dichlorodi-phenyl trichloroethane)

-

1

-

-

42.    

Demeton-Skin

0.01

0.1

-

-

43.    

Diazinon-Skin

-

0.1

-

-

44.    

Dibutyl phthalate

-

5

-

-

45.    

Dichlorvos (DDVP)-Skin

0.1

1

-

-

46.    

Dieldrin-Skin

-

0.25

-

-

47.    

Dinitrobenzene (all isomers)-Skin

0.15

1

-

-

48.    

Dinitrotolune-Skin

-

1.5

-

-

49.    

Diphenyl-(Biphenyl)

0.2

1.5

-

50.    

Endosulfan (Thiodan)-Skin

-

0.1

-

-

51.    

Endrin-Skin

-

0.1

-

-

52.    

Ethylacetate

400

1400

-

-

53.    

Ethyl alcohol

1000

1900

-

-

54.    

Ethylamine

10

18

-

-

55.    

Fluorides (as F)

-

2.5

-

-

56.    

Fluorine

1

2

2

4

57.    

Formaldehyde (S.C.)

1.0

1.5

2

3

58.    

Formic acid

5

9

-

-

59.    

Gasoline

300

900

500

1500

60.    

Hydrazine-Skin (S.C.)

0.1

0.1

-

-

61.    

Hydrogen chloride-C

5

7

-

-

62.    

Hydrogen cynide-Skin-C

10

10

-

-

63.    

Hydrogen tluoride (as F)-C

3

2.5

-

-

64.    

Hydrogen peroxide

1

1.5

-

-

65.    

Hydrogen suylphide

10

14

15

21

66.    

Iodine-C

0.1

1

-

-

67.    

Iron-Oxide Fume (F°20) (as Fe)

-

5

-

-

68.    

Isoamyl acetate

100

525

-

-

69.    

Isoamyl alcohol

100

360

125

4500

70.    

Isobutyl alcohal

50

150

-

-

71.    

Lead, inorg, dusts and fumes (as Pb)

-

0.15

-

-

72.    

Lindane-Skin

-

0.5

-

-

73.    

Malathion-Skin

-

10

-

-

74.    

Manganese (as Mn) dust and compounds-C

-

5

-

-

75.    

Manganese fume (as Mn)

-

I

-

3

76.    

Mercury (as Hg)-Skin-

(i)       Alkyl compounds

(ii)     All forms except alkyl vapor

-

-

0.01

0.05

-

-

0.03

-

77.    

Aryl and inorganic compounds

-

0.1

-

-

78.    

Methyl alcohol (Methanol)-Skin

200

260

250

310

79.    

Methyl Cellosolve (2-Methoxyethanol) Skin

5

16

-

-

80.    

Methyl isobutyl ketone

50

205

75

300

81.    

Methyl isocyanate-Skin

0.02

0.05

-

-

82.    

Napthalene

10

50

15

75

83.    

Nickel carbonyl (as Ni)

0.05

0.35

-

-

84.    

Nitric acid

2

5

4

10

85.    

Nitric oxide

25

30

-

-

86.    

Nitrobenzene-Skin

1

5

-

-

87.    

Nitrogen dioxide

3

6

5

10

88.    

Oil mist-mineral

-

5

-

10

89.    

Ozone

0.1

0.2

0.3

0.6

90.    

Parathion-Skin

-

0.1

-

-

91.    

Phenol-Skin

5

19

-

-

92.    

Phorate {Thimet)-Skin

-

0.05

-

0.2

93.    

Phosgene (Carbonyl chloride)

0.1

0.4

-

-

94.    

Phosphine

0.3

0.4

1

1

95.    

Phosphoric acid

-

1

-

3

96.    

Phosphorus (yellow)

-

0.1

-

-

97.    

Phosphorus pentachloride

0.1

1

-

-

98.    

Phosphorus trichloride

0.2

I.5

0.5

3

99.    

Picric acid-Skin

-

0.1

-

0.3

100.   

Pyridine

5

15

-

-

101.   

Silans (Silicon tetrahydride)

5

7

-

-

102.   

Sodium hydroxide-C

-

2

-

-

103.   

Styrene, monomer (phenylethylene)

50

215

100

425

104.   

Sulphur dioxide

2

5

5

10

105.   

Sulphur hexafluoride

1000

6000

-

-

106.   

Sulphuric acid

-

1

-

-

107.   

Tetraethyl lead (as Pb)-Skin

-

0. 1

-

-

108.   

Toluene (Toluol)

100

375

150

560

109.   

o-Toluidinz-Skin (S.C.)

2

9

-

-

110.   

Tributyl phosphate

0.2

2.5

-

-

111.   

Trichloroethylene

50

270

200

1080

112.   

Uranium, natural (as U)

-

0.2

-

0.6

113.   

Vinyl chloride (H.C.)

5

10

-

-

114.   

Welding fumes

-

5

-

-

115.   

Xylene (0-, m-, p-isomers)

100

435

150

655

116.   

Zinc oxide­

(i) Fume

(ii) Dust (Total dust)

-

-

5.0

10.0

-

-

10

-

117.   

Zirconium compounds (as Zr)

-

5

-

10

ppm³             Parts of vapour or gas per million parts of contaminated air by volume at 25.C and 760 torr. (mm of mercury).

mg/m²      milligrams of substance per cubic metre of air.

*              Not more than 4 times a day with at least 60 min. interval between successive exposures.

** mg/mm^{2 =}   Molecular weight x ppm
                            24.45

C           denotes ceiling limit.

Skin     denotes potential contribution to the overall exposure by the cutaneous route includ­ing
mucous membranes and eye.                                                                

S.C.      denotes suspected human carcinogens.                            

H.C.      denotes confirmed human carcinogens.

450 x mcgniti< Respirable DUi Fraction passin Acrodynar

Substance                             Permissible time-weighted average concentration (TWA) (8 hours)

Silica, SiO2

(a) Crystalline
(i) Quartz

(1) In term of dusts count      10600                   mppcm
                                             % Quartz + 10

(2) In terms of respirable dust                 10                      mg/m²
                                                          respirable Quartz + 2  

(3) In terms of total dust                     30                        mg/m²
                                                        % Quartz + 3

(ii) Cristobalite                  Half the limits given against quartz

(iii) Tridymite                    Half the limits given against quartz

 (iv) Silica, fused               Same limits as for quartz

(v) Tripoli                         Same limit as in formula in item (2) given against quartz

(b) Amorphous Silicate        10mg/m3, Total dust

Asbestos (H.C.)        *2 fibres/ml, greater than 5 urn in length and less than 3 urn in breadth
Portland cement        10 mg/m3, Total dust containing less than 1 % quartz
Coal Dust                  2 mg/m3, respirable dust fraction containing less than 5% quartz

-------------------------------------------------------------------------------------

mppcm -- Million particles per cubic meter of air based on impinger samples counted by light­-field techniques.

*As determined by the membrane-fiter method at 400--

450 X magnification (4 mm objective) phase contrast illumination.

Respirable Dust:

Fraction passing a size-selector with the following characteristics:

        Aerodynamic Diameter (u.m.)        %passing sector 
             (Unit density sphere)                                  
                     < 2                                 90 
                     2.5                                  75
                     3.5                                  50
                     5.0                                  25
                     10                                    0