OEL Reference Note E 2000

A ReferenceNote on

OccupationalExposureLimits

for

ChemicalSubstancesin the

Work Environment Thisguidebookispreparedby the OccupationalSafety and Health Branch LabourDeoartment

This editionOctober 1998

This guidebook is issued free of charge and can be obtained from offices of the Occupational Safety and Health Branch. Addresses and telephone numbers of "The the offices can be lound in he booklet Labour Department Offers You its Services"or bv teleohone2559 229'7 .

Printedby the Printirg Department 1660004 .+0L 5/2000 (Printed on paper made from woodpulp derired l'r'om rene$able lbrests) Content

Page 1. Introduction 5 2. UnlistedSubstances 6 3. Prohibitionof the Useof Substances 6 4. OocupationalExposureLimits 1 5. Excursion 8 6. UnusualWork Schedules 8 7. PhysicalFactors 8 8. SkinAbsorption 9 9. SimpleAsphyxiants 9 10. Carcinogens ) 11. Sensitisers 9 12. AirborneParticulates 9 13. MixedExposure 10 14. Expressionof ExposureLimits 10 15. FurtherInformation ll

AppendixI List of publicationson Workers'Health T2

Tableof OccupationalExposureLimits 13

UsefulInformation 51 This PageIntentionally Left Blank l. Introduction Chemicals used in the industry may become airborne in the working environment and cause different kinds of adversehealth effects on workers. While it is recognized that exposure to chemical substances should be kept as low as reasonably practicable, guidance in the form of exposure limits may be used by occupational health and safely practitioners, employers and employees or their representativesto assist them in designing devices or to take appropriate measuresin order to protect the workers adequately lrom chemical hazards. The aim of this publication is to provide a referencein the form of Occupational Exposure Limits (OELs) to assessthe adequacy of the control measu.restaken for the chemical substanceswhich are commonly found in local industry. These Occupational Exposure Limits represent airborne concentrations of individual chemical substance.ExDosures of workers to these airborne chemical substanoesshould be kept as low as possibleand should not exceed the OELs so that the workers are protected from adverse health effects arising from their repeated exposures day after day. Relerence is made to the American Conference of Governmental Industrial Hygienists' list of Threshold Limit Values and the standards of other overseasorganizations in establishing the OELs containedin this booklet. It is important to appreciate the following aspects thoroughly before applying or interpreting the OELs: (a) The OELs are not Jine dividing lines betv,eensafe and dangerous concentrations.Rather they are used as guidelinesto assessthe working environment and to indicate whether additional control measuresare requlreo. (b) Exposure to airborne chemicals should always he kept as low as reasonahlyprtcticable even though the current OELs are not exceeded.One of the reasons is due to individual susceptibility; a small proportion of workers may still be affected by some chemical substancesat concentrations around or below the OELs. Another reasonis becausemany of the OELs are establishedon cuffent but limited scientific toxicological knowledge of the substances;a more stringent OEL may be adopted in future in the light of new toxicological knowledge. (c) The evaluation or monitoring of hazards of atmospheric contaminants in workplaces is often a complex task. It involves thorough understanding of the work processes!good knowledge of the toxic effects of the chemical substances,adoption of appropriate sampling strategy, suitable choice of sampling and analytical method, correct useof sampling equipment and many other factors. Therefore, it is essentiallhat thoseapplying or interpreting lfte OELs in such hazard evalualions should be someone witlx appropriate training, knowledgeand experiencein occupational hygienepractice (d) The OELs only consider absorption ol chemicals by inhalation and are valid only whensignificant skin absorption doesnot occur. (a) The OELs are not relative indices of toxicity of the chemical substances. (/) The OELs should not be used in the evaluationof non-occupational exposuressuch as evaluation of community air quality, and in the estimation the toxic potentiai of continuous or uninterupted exposures. (g) The OELs may not be applicable directly to indoor air pollution problems in non-industrial work environments. (ft) The OELs may be amended when new toxicological knowledge, medical or scientific evidence supports the necessity for such an amendment.

2. Unlisted Substances OELs have not been assignedto all chemical substancesused in industry. However, it does not imply that those not assigned with OELs are safe or non hazardous. In many instances, there is insuificient information to warrant development of an OEL for a chemical substance.In other instances,the use of the chemical substancedoes not produce a significant airborne level of contaminant and an OEL is not necessary.In addition. there are some chemical substancesof considerabletoxicity that have been omitted primarily becauseof their limited uses. Whenever an OEL has not been assigned to a chemical substance, it will be necessaryfor employers to establish their own work practices and standards lor control so that adequatecontrol of exposureis provided. Furthermore, it is a good hygienepractice to keep exposure to any chemical substancesas low as reasonablypracticable and handle them with due care.

3. Prohibition of the Use of Substances There are some chemical substancesof which the use or the method of use is orohibited. Details of these chemical substancescan be found in the IOUOWTnC: (a) Factories and Industrial Undertakings (Blasting by Abrasives) Special Regulations concerning the prohibition of the use of sand or other material containing free silica as an abrasive in any blasting process. (b) Factories and Industriai Undertakings (Asbestos) Special Regulations concerning the prohibition of: (i) spraying of asbestosor any material containing asbestosor asbestosdust; (ii) use of crocidolite, amosite or any substance containing either of thosemineralsin anv nrocess. (c) Factories and Industrial Undertakings (Carcinogenic Substances) Regulations concerning the prohibition of use of: (i) beta-naphthylamineand its salts; (ii) benzidineand its salts; (iii) 4-aminodiphenyl and its salts; (iv) 4-nitrodiphenyl and its salts; and any substance containing any of thesechemical compounds. OELs havebeen assignedto someof thesechemical substancesbecause oftheir existenceas a result of past use.

4, Occupational Exposure Limits In this reference nots, there are three categories of Occupational Exposure Limits all referring to the exposure of workers in a working environment. They are defined as follows: (a) Occupational Exposure Limit Time-Weighted Average (OEL TWA) it is expressed as the time-weighted average of the airborne concentration of a chemical substanceover an eight-hour working day, for a five-day working week unless otherwise stated. Only when the personal exposure of any worker to that chemical substance over an eight-hour working day is kept at or below such concentration, the control of the airborne chemical substance may be considered adequate. In the eight-hour averaging period of a working day, excursions above the OEL-TWA are permitted provided that these excursions are compensatedfor by equivalent excursionsto maintain exposures below the limit. However, since some chemical substancescan produce acute health effects even after brief exposuresto high concentrations, excursions above the OEL-TWA should be restricted. The following two types of OE L are introduced to restrict suoh excursions. (&) Occupational Exposure Limit Short-Term Exposure Limit (OEL STEL) it is expressed as a l5-minute time-weighted average of the airborne concentration of a chemical substanceunless otherwise stated. It should not be exceededat any time during a workday even though the 8-hour time-weighted averageexposure is within the OEL TWA. Exposures above the OEL-TWA up to OEL-STEL should not be more than 15 minutes and no more than 4 times a day.A minimum of 60 minutes should be allowed between successiveexposures in this range. The OEL-STEL pror"idesa guideline for the control of the short term exposure. It is an important supplement to the OEL-TWA which is more concerned with the long term exposure to airborne contaminantsover long periods of time. (c) Occupational Exposure Limit-Ceiling (OEL-C)-it is expressedas the airborne concentration of a chemical substance that should not be exceededduring any part of the working exposure. If instantaneous monitoring of the concentration of the airborne substance is not feasible,the OEL-C can be assessedby sampling over a l5-minute period except for those chemical substancesthat may cause immediate irritation when exDosuresare short.

5. Excursion For most of the listed chemical substances,there is not enough toxicological inlbrmation available to warrant an OEL-STEL or OEL-C. However, excursions above the OEL-TWA should still be controlled. It is recommended that as a general guideline excursionsshould not exceedthree times the OEL-TWA for more than a total of 30 minutes during a workday and under no circumstances should they exceed five time the OEL-TWA provided that the OEL-TWA is not exceeded.When an OEL-STEL or OEL-C is establishedlor the chemical substance, it will supersedethis general excursion limit regardlessof whether it is more or lessstringent.

6. Unusual Work Schedules The OEL-TWA is expressed as a time-weighted average concentration oi that chemical substance over an eight-hour working day and lor forty hours a workweek. When workers have a work schedule longer than eight hours a day or 40 hours a week pattern, the OEL-TWA may need to be reduced by a suitablefactor to ensureadequate worker protection. Expert advice should be sought in such modification of OELs. As a rough guide, the OEL reduction factor (RF) may bederived by the Brief and Scalamodel: for more than 8 hours per day, nr=-8^2a h h 16 where h = hours worked per day, lor more than 5-day and 40 hours per week, R tr =40.'. 168- H H' t28 where H = hours worked oer week.

7. Physical Factors Physical factors such as high temperature, abnormal pressure, ultraviolet radiation may increasestrssson a worker so that the effects of an exposure to an airborne contaminant at the OEL may be changed. These stressescan act adverselyto increasethe toxic response of the contaminant in many instances. Therefore, an OEL should be applied with caution when there is gross deviation lrom the normal situation. 8. Skin Absorption In general, the main route of entry into the body for most chemical substancesis by inhalation and the OELs in this booklet solely refer to exposure by this route. However, there are some chemical substanceswhich can penetrate the intact skin and be absorbed significantly into the body. These 'Sk' chemical substancesare marked with the notation in the list of OELs. When there is potential exposure of skin to such chemical substances,further control measuresagainst skin absorption are necessaryin addition to those against inhalation hazards.

9. Simple Asphyxiants Some gasesand vapours, when present at high concentrations, can reduce the oxygen content in the air to such an extent that life cannot be supported. They act as simple asphyxiants.Many of them are odourless,colourlessand not easily detectable. lt is important to ensure that the oxygen content of air should never be less than 18% by volume under normal atmospheric pressure when such simple asphyxiant is present. Moreover, many asphyxiants have a fire or an explosion risk at concentrations well below those at which asphyxiation is likely to occur. Extra precautions or control are therefore further required to avoid the presenceof concentrations liable to causea fire or an explosion.

10. Carcinogens Some of the chemical substances listed in this booklet are confirmed or suspectedhuman carcinogens. They are indioated with the notations @, A1 and .A2 in the table of OELs. Exposure to carcinogens should preferably be prevented. If this cannot be achieved, exposure should be kept to the minimal so far as reasonablypracticable and always below the OELs.

11. Sensitisers Some chemical substances may causesensitisation of the respiratory tract when inhaled. Once after sensitisation, an affected individual may subsequently produce symptoms of ill-health after exposure even to minute concentrations of the sensitiser.Compliance with the OEL may not provide adequate protection for a hypersensitiveindividual. Exposure to sensitisersshould preferably be prevented. If this cannot be achieved, exposure should be kept as low as reasonably practicable. In the table of OELs, those respiratory sensitisers are 'Sen' assignedwith thc notation.

12. Airborne Particulates Except for crystallinesilica, asbestosand raw cotton dust. the OELs for 'inspirable the airborne particulates included in this publication refer to the dust' unlessotherwise stated.The 'inspirabledust'is the airborne dust which may enter the respiratory system during breathing. The recommended exposure limits of airborne crystalline silica, asbestos and raw cotton dust are also produced in the table of OELs but readers are strongly advised to look into the details of the exposure limits and their applications in their relevant Reference Note, Code of practice and protection of Workers' Health Seriesproduced by the Labour Department.

13. Mixed Exposure

The exposure limits listed in this booklet are for single compounds. However, workers are frequently exposedto a mixture of compounds. The health effect of a mixture is a complex issue and it can be entirely different lrom those of the individual components. Some components act on 'independent, different tissues or organs and their effects are of each other. In some casesthe individual components act on the same organs or by similar 'additive'. toxicological mechanismsand their effectsare in other casesthe overall effect is much greater than the sum of the individual effects and the 'synergistic'. 'potentiation, effects are There are also cases when one component has an effect but the second component does not but enhance the effectof the lormer one in mixedexposure. 'Synergism and Potentiation' When casesof synergism and potentiation are encountered, more strict control is required. Expert advice should be sought when these kinds of interaction are suspectedto exist. Additive Effects'-When the effects of the 'additive'and components of the mixture are the OELs are based on the same health eflfects,the mixed exposureshould be assessedby the formula: Cr C, * + 93 +....

14. Expressionof Exposure Limits In the table of OELs, the airborne concentrations of all the substancesare expressedin milligram of the substance per cubic metre of air (mg/m3) under

10 the environmentalconditions of25oC and one atmosphericpressure101.3kPa with the exception of asbestos which is normally expressed as fibres per millilitre of aii. For gasesand vapours, the concentrations are expressedin parts of the substanceper million parts of the air (ppm) by volume. The following formula can be used to convert the concentration in ppm to mgm': plm concentration in mg/m3= Urflq!$e$#entrq!9lln

15. Further Information A series of booklets on other topics of workers' health and occupational health hazards are shown in the Appendix I They are available free of charge from Occupational Health Division of the Labour Department, at 15lF-' Harbour Building, 38 Pier Road, Central, Hong Kong. In case there is still any further problem on occupational health and hygiene aspects,all employees and employers are welcome to make enquiry to the office or through telephone 2852404r.

l1 Appendix I

List of booklets on Workers, Health A ReferenceNote on Control of Asbestos at Work A ReferenceNote on Ventilation and Maintenance of Ventilation Systems Guide to Occupational DiseasesPrescribedlor Compensation purposes Hr]r_tsog FiTt Aid (For: Notifiable Workplaces, euarries, Cargo & Container Handling Undertakings, and Construction Sites and other workplaces) Notes on the Diagnosis of Occupational Diseasesprescribed under the Employees' Compensation Ordinance

The Protection of Workers' Health Series -Control of Toxic Substancesin Workplace -Cyanide Hazard in Industry-Poisoning prevention and Treatment Electroplating HealthHazards Health Guide on the useof Visual Display Unit -Health Hazardsin Demolition Work -Health Hazards of Diving ManganeseDioxide Prevention of Back Injury RespiraroryProtecLiveEquipment -Silica SolventHazardsin Printins Industrv Solvents

Code of Practice Control of Lead at Work -Diving -Protection of Cotton Spinning Workers from Byssinosis Protection of Quarry and Construction Workers from Silicosis -Protection of Ttnnel Workers from Silicosis

Health Brochures Health Hazardsof Asbestos -Health Hazards of Weldins Respirator for Silica Dust Safe Use of Toluene-di-isocyanate (TDI) and Methylene-diisocyanate (MDD SkinDiseases inlndustry -Solvent Hazardin ScreenPrintins

12 Table of Occupational Exposure Limits When making referenceto the following table, you are strongly advisedto read the content ofthe aforepagescarefully in the first instance. Below are the explanatory notes and remarks for the table: Explanatctry Notes: Nomenclature The chemical names used in this booklet are in accordance with the nomenclature rules of the International Union of Pure and Applied Chemical (IU PAC) or the common names. A1l prefixes, e.g. n-, tert-, o-, are disregarded when listing the substances in the list of OELs in 'iso' 'cyclo'. alphabetical order except the prefixes and CAS Number -The Chemical Abstracts Service Registry Number (CAS No.) of the American Chemical Society is a number to identify each individual chemical. Each chemical is uniquely assignedwith a single code. This number is also shown, lor most substancesin the table of OELs for the readers'reference. ppm -parts permillion in terms of volumeby volume m o/rl l -milligramspercubicmetreof air fl/mL fibresoer millilitre of air Remarks: A1 Confirmed Human Carcinogen by American Conference of Government Industrial Hygienists (ACGIH). A2 SuspectedHuman Carcinogenby ACGIH. A3 Animal Carcinogenby ACGIH. L4 Not Classifiabieas a Human or Animal Carcinogenby ACGIH. ,45 Not Suspectedas a Human Carcinogenby ACGIH. @ Substanceidentified by other sourcesas a suspectedor confirmed human carctnogen. D The value is for total dust containing no asbestos and

13 OccupationalExposure Limits ffi*ffisEF

TIT/A :]TEL Ceiling ChemicalICAS#] fl+ETY,Jtr lEffiRffiWH RHRffiI'FItr Remdrks It Efr, ppm nglml pptn mgtt1" ppm mglmr IEdL

Acetaldehyde [75-07-0] 25 45 @,A3

Aceticacidf64-19-7] 10 2) asm(zm-) 15 37 Acetic anhyddde [08-24-7] 5 21 Ag[F] Acetone[67-64-1] 500 1188 750 1182 A4 trEltJ Acetonitrile[75-05-8) 40 6'77 60 l0l

Acetylchioride[75365] N.E.

Acetylene[74-86-2] SrmpleAsphyxiant LW ),E1?.4.1++,evnhl' Acrolein[17-02-8] 0.1 0.23 SK,A4 r.!{fiE* Acrylic acid[79-10-7] 2 5.9 sk, ,A4 FffiAT Alcohol,denatufed ftww N.E. Allyl alcohol! 07-18-61 2 4.8 4 9.5 SK E,X6A+ 4-Aminodiphenyl[92-67-l]andits salts @,A1. Sk,prohibited 4-*4W+&^Effi +,H TWA STEL Ceiling Remurks ChemicalICAS#] F+a+fl{a tugREtFts REEffiWffi ,f1.4fr Ppm tngtm ppm mglm3 ppm mglm' l$;l

Ammonia[7664-41-7] 1'77 35

Ammoniumdichromatc,see Chromium (VI) compound trffiM.&' HM N\ 4Lli+h Ammonium fluorosilicate, seeFluorlde ffiE+Wgt'F-F',|V.\h Amosite,seeAsbestos ffiE.{fi,traffi n-Amyl acetate[628-63-7] r00 532 ]t AfiA{IiAF sec-Amylacetate 125 'f+SHAC,:tAk1626-38-01

Amyl alcohol, mixed isomers, with the N.E, exceotion of tert-pentan ol fts+..qtS€giEA+,, +u\wl*tt' sk, A3 Aniline 162-53-31and homologues 7.6 @, xlieH-"14.N4 Aniline[62-53-3],saltsof N.E. +E{W Antimony[7440-36-0]and compounds.as Sb ffitjy.(t6+n ' D.F;ffiEH, Antimonypentachloride,seeAntimonv n€.ltffi,f,ffi Antimony trichloridq seeAntimony -F,|U.aX.,nffi Arsenic,elemental[7440-38-21and inorganic AI compounds.(exceptArsine),as As 6F'nA &ft KiLA+n ttr.."iq t\, ll,E{+AH TWA S7'EL Ceiling ChemicalICAS#] T+E+JIJE Eg#EIE{H REEEIF{H Remurks lbe,n ppm ttglnt ppm nglml l1ptll klgtm lfr at

Arsine[7784-42-l] 0.05 0.l6 iF ( {'l,fLfi ) Asbestos Etft Chrysotile[ 200]-29-5] Referto Factoriesand iH6,l'B( fiEffi ) Industdal Undertakings Other forms (Asbestos)Regulation H1&&ffi 4ratfrt.rL.r*fiEg 6+il*Hbl Asphalt(petroleum)fumes[8052-42-4] j;rs*+(fiiil).l4;f

Badum[7440-39-3],solublecompound,asBa tA' itr6lu.a+h,ult+F€H Bariumperoxide.seeBarium €fi,iLst, F.fF

Benzalchloride[9R-87-]1.seeBenz) lidene chloride f ](-F.F,1rt+-F Benzaldehyde N.E. *rya+ [100527] Benzene[71-43-2] 0.5 (4,A) ,F 1,3-Benzenediol [08463] N.E. ,F{jF -g} Benzidine[92-87-5]and its salts @,Al, Sk,prohibited qfr+fltr\xw r{, tl:j

Benzo(a)pyrene[50-32-8] @,,A2 3 , 4-++lL TI4'A STEL Ceiling g]*EE Remarks Chemical ICASlt] 8+F+jttr E l'RIH R,aFffittFH ILryH ppm mgtm' ppru mglm' ppm mglm' lh;l

Benzoylchloride [98-88-4] 0.05 #Fmfi Benzoylperoxide[94-36-0] i&F\'iL-+qrim N.E, Benzylalcohol [100516] -* fie Benzylbenzoate 20514] N.E, *rym-FAb[ A3 Benzylchloride[ 00-44-7] 5.2 @, -F4F (fi,fb-F) N.E. Benzylidenechloride1988731 +T4-fi =j Beryfliuml'7440-4lr-11andcompounds.asBe 0.002 0.01 @,A1 t&.rj..J!It"E+,,t . i,{X!t€,H N.E. Borontrichloride [10294345] .rF'fLini 2.8 Boron trifluoride [7637-07-2] I -fi11i'8fl

Bromine[7726-95-6] 0.1 0.66 0.2 1.3

N.E. Bromoaceticacid[79083] IEAEM(iFZM ) Bromomethane. seemethyl bromide tF,fLftrift, E+rEiR A2 1,3-Butadiene [106-99-0] 4.1 @, l. r.,ifr-[,3] Butane [06-97-8] 1900 TWA STEL Ceiling ChamicalICAS#] si +jilH. tsgFEtt7H REEEI1F4H Rematks fl:4fr ppm mglm' ppm ntglm' ptn mglm' l#;i

l-Butanol,see n-Butyl alcohol r-E+-t1l, _F.Era+ 2-Butanol,see sec-Butyl alcohol TH -t2t, F.i+Tfr? 2-Butanone, see Methyl ethyl ketone (MEK) l Alil-[2] , -trqr4a€+glil 2-Butoxyethanol(EGBE)[1I l-76-2] t2l SK 2-TF..ELW n-Butylacetate u23-86-41 150 713 950 AfiMltTAS n-Butylalcohol rl -36-31 152 Sk E TE? co n-Butyl acrylate[4] -32-2) 10 A4 tr i dfFmag sec-Butyl alcoliol [78-92-2] 100 303 i+TA+ tert-Butyl alcohol[75-65-0] 100 f,{ I'E+ Cadmium,elemental [7,140-43-9] and compounds,asCd ffi ' )ne,&,\?,+M,lzl,litFFF. Total dust 0.01 A2 ++t,E Respirabledust 0.002 nInE^'M.@ Cadmiumoxidc [1306-19-0], see Cadmium, elementaland compounds,as Cd q.fLrF g"cl,s ,r_4.&fL.Ar,4 l/ -Htq TWA STEL Ceiling ClwnicalICAS#J Ee"TYtlE EgREIWIE RHEEIFf4 Remarks ItFffi ppft1 mglm) ppm mgtm' ppm mglnt' ffi i+

Calciumcarbonate[ 317-65-3] ffimf4 Total dust l0 D ++JiE Respirabledust 3 sIttT).iikE CalciumcarbideP52071 N,E. r&.tLg5 Calciumhypochlorite,seeChlorine iiiFrffif4 '_F.fi Catciumsulphate[77?8-18-9] 6imic Totaldust 10 +ytfr Respirabledust 3 t,Is&,\iit,F Calomel, seeMercury inorganic compounds t| ne, .F,zl<$Rff{4'fLA42 Camphor,synthetic[76-22-2] t2 A4 1+l'A,Alt Carbonblack[1333-86-4] 3.5 @, A4 fr,R Carbondioxide[ 24-38-9] 5000 9000 30000 54000 - '-r11t{& Carbon disulphide[75-1 5-0] l{J 3l sk -rtjnlL.#n monoxide 25 29 Carbon-,{'1brr,t [630-08-0]

Carbon tetrachloride[56-23-5] 5 31 63 @,42, Sk lqfi1titr TWA STEL Ceiling ChemicdlICAS# I t+F."'ffrfA trgEEIIEE iiB *reIF{E Remq*s ILryfi ppm nglm' ppm mglmt ppm mglmt f$it

Carbonyl-FliLit(Bf,l chloride, seePhosgcne , H,iE+i Causticpotash,seePotassiumhydroxide ff14fH'_Rafi,ihfli Causticsoda,see Sodium hydroxide ff,|+ift. nag,.ir$i& Cellulosenitrate [9004700] N.E. hHWt&*.EA Chlorinc[7782-50-5] 0.5 1.5 A4

ChloroacclicacidU9l l8l N.E, fiAAM (J O Chloroacctylchloride [79-0,1-9] 0.05 0.23 0.15 0.69 SK FZfif;:Fi Chlorobenzenc[08-90-7] 10 A3 *t.+ Chlorodiphenyl(42%chlorine)[53469-21-9] I SK +aqffi+$2'kA) Chlorodiphenyl(54% chlorine)[11097-69-l] 0.5 sk, A.3 Fi6fi+(54%fi) I-ChJoro-2,3-epox.vpropane, seeEpichlorohydrin r-Jr't-2 3-ffifl''r; [&irffi Chloroform167-66-31 l0 19 @.43, Sk Fi/i Chloromethane, seeMethyl chloride EF{i , -F,LF*fi bis(Chloromethyl)ether [542-88-1] 0.001 0.004'7 @,.A1 €(a414)stt TWA STEL Ceiling ChemicalICAS#] r+.F+frffi fugREW{H RBREWtr Remarks 11.ry,fl, ppm mglm' ppm mglm' ppm mglm' l#;i cr-Chlorotoloene. seeBenzyl chloride a-fiFX,-F,'fi45 Chromium P440-47-31

Metal 0.5 +tr Chromium(II) compounds,asCr 0.5 i+(rDIz./iryx, D. ffiEH Chromium(III) compounds,as Cr 0.5 A4 ffi(n)l?.at , Uc^ffiAH Chromium(VI) compounds,asCr ffi(.vD|LAW,UHffiEH Watersoluble 0.05 @,A1 zKE'llt Certain water insoluble 0.01 @,Ar Ftr/Fi](16,l4 Chromiumtrioxide,see Chromium (VI) watersoluble compounds -F"\Lffi , HffiN\TKjElt,lj.&1n Chrysene[218-01-9] @,A3 tsi Chrysotile,seeAsbestos iRNT,F, -RE&E Coal tar pilch volatiles [65996-93-2], @,Al as cyclohexane solubles l++ ;HiE 5JFCfl9 l {ni.#diffic P------'F H Copper[7440-50-8] fl4 Fume ,Effi TWA STEL Oeiling ChemiculICAS#] trF1.tr{E EgEEFPtr RBEffileH Remarks fl:ry,fl ppm tnglml ppm mg/mr ppm mgltn lfril

Dusts& mists,asCu ]H.Efr'#,x4tt"J€H Cottondust,raw Referto Codeof ]Fffi,8 Practicelbr Protection of Cotton Spinning Workers l'rom Byssinosis 4F€Fitl:tEfrI-,t'.,B ,.}EULffiPJNEffiZTIF

Crcsol[1319-77-3],allisomers sk ryerr),tiaRi#fle Cristobalite,seeSilica--Crystalline S )r4'EtLFatRE+4 Crocidolite,seeAsbestos HhTfl' HETft Cumene[98-{t2-8] 246 SK ,tfiii Cumene hydroperoxide [80159] N,E, iE-rr.'fb6,14/6 Cyanides, as CN SK 3.{L{4 ' tlr.}f cN FH Cyclohexane[110-82-7] 1030 we\i, Cyclohexanol[108-93-0] 206 SK HEA+ Cyclohexanone [108-9,1-l] 100 SK,A.4 ffi-ald Cyclohexanoneh;r'droperoxide N,E. €fiiLaqtsaFl TWA STEL Ceiling ChenicalICAS#] n+E+frtr TEWRffiIWIE frfrRffiWlli Remarks 'IL,H,F, ppn mglm' lpm mglm' pptn mgrnl tH df

Cyclohexanoneperoxide [2262587] N.E. ,Efi,ftilx - HliJ DDT (Dichlorodiphenyl-trichloroethane) @,A3 I50-29-31 irfiiJfri#( -rfiEfr+ -F,L'fr') I, 2-Diirminoethane.iee Fth) lenediamine | , 2-:.taELE,.HL,t{. o-Dianisidine[119904] N.E. *t\qfrk6tra o-Dianisidinesalt N,E. iffi!!iFi6,{qfs f)iatomaceousearth,see Silica Amorphous (\, i+Hl: , F,{+.E-]Fffi#H Diazinon [333-41-5] sk, 44

Dibenzoyl peroxide, sceBcnzoyl peroxide it4fiit-*42 :AFJ, E,]8fi,,fL-*rym 1, 2-Dichlorobenzene,-A+, see o-Dichlorobenzene 1 ' 2- F.iHJ-f6. 1, 4-Dichlorobenzene,-g+, seep-Dichlorobenzene I ' 4- t{fi-fi+ o-Dichlorobenzene [95-50-1] 150 50 301 A4

p-Dichlorobenzene|06-46-'71 10 60 A3 91- -Tt+ Dichlorodifluoromethane[75-71-8] I 000 4 950 A4 :-,tsr'fi+'16 1. l-Dichloroethane[75-3,1-3] 100 405 A4 | ' r ,aL$i TWA STEL Ceiling ChemiculICAS#] !+E+/'ttE fu'gFEWE &EREINE Remerk.s 'f1,e,7, ppm mglml ppm nglmt ppm mglm3 lH;+

l, 2-Dichloroethang seeEthylene dichloride 1,2--.-ri\LR'F,-fiibaffi Dichloroisocvanuri-€EA,trA4 c acid121 825721 N.E.

Dichloromethane,seeMethylenechloride -qFfi ' _H+F4-fi s. c-DichlorotolueneI988731 N.E. a , o- -.Fri*l Dichloro-1,3. 5-triazinetrione,see Dichloroisocyanuricacid -fi-l' 3' 5--E -Al4,,R--fiqg,.Em

19 Dichloro-1,3, 5-triazinetdone,potassrum saltof, seePotassiumsalt of Dichloroisocyanuricacid h-r r . 5-'4 ..aFlzfr#F. fl-F. F1trmzfFffi Dichloro-1,3, s-tiazinetrione,sodium salt of, seeSodium salt of Dichloroisocyanuricacid .h-r . .l . s- .4 .fiEZlFrH.H-.hE fi,EAAZtftffi Dieldrin[60-57-1] 0.25 @,sk,A4 ?,(ft4i Diethylamine!09-89-71 l5 l5 4) sk, ,A.4 a) k\ [1I1 -40-0] 4.2 SK ?1H91_,;J""-''e ether. Diethyl-ZAS'-F,ZMsee Ethyl ether TIIJ'A STEL Ceiling Remarks Chemical ICAS#] fl+E+jttEi F.HF.EWTE &tiiFffif?fg {1ry,fl ppm mgtm' ppm ruglmr ppm mglmr lffi;t

kctone 1057 Dieth)l-.AE [96-22-0] -- m-Dihydroxybenzene[108-,16-3J l0 90 L4 HJ+-&i Dilauroylperoxide[105748] N.E. d.+i,fL-Il t+6ffi 3, 3'-Dimethoxybenzidine,see o-Dianisidine 3 , 3'--Ffi+q6i.t&, .trihfiEiH6,s? 1,2-Dimethoxyethane u 107l4l N.E 1 ' 2--trF,EL'Xi Dimethylamine1 24-40-ll 9.2 2'77.6 A4 - ,f rt< t-) Dimclhylbenzene, sceXylene --H -js ' -R xylcne a. o,-Dimethylbenzyl hydroperoxidc [80159] N,E. a ' u--Hf 4t6-+riL6i Dimethyldichlorosilane[75785] N.E. F +-Frfr+'tt Dimethyl ether [115106] N.E. -Fffi I 2-2] t0 30 q.L A/ Dimethylformamidc- [68- F -1,!Tr&R,1'4 Dimethylsulphate[77-78-1] 0.1 0.52 @,A3, Sk ifiA7t.4raF Dinitrobenzene[528-29-0:99-65-0; 0.1s I SK 100-25-,ll(allisomers) rH4+ (Aq,ffigg) Dinitrotoluene[25321-14-6] -'{ril8 rt'r'F TWA STEL Ceiling Chemi(alICAS#] ffiE+frfti *gRffiPFE &EREIWE Remarks It4H ppm mglmi ppm mglnP ppm mglmr ffi;+

l, 4-Dioxan, seeDioxane I , 4-'fib-lH1'-tr-ttg6 Dioxane[23-91-1] 25 90 @.sk.A3 - n+,1? Diphenylmerhanediisocyanate,see Methylene-,EH,A€AE''bisphenylisocyanate -+ F,!i jt -* +r€,95, AqrE"' Epichlorohydrinll 06-89-81 1.9 a qL A1 tfim+ EpoxyResin:-Reactionproductof Bisphenol N.E. A and Epichlorohydrin (averagemolecular weightnot morethan 700) N) IHfiH,8B: EWit D,*.'€tM.?-F,ffiEth ('F.ltJr|+it4.6Ei@700) Ethane-I, 2-diol. seeEthylene glycol Lri--E?-V' 4' nL--W Ethanethiol, seeEthyl mercaptan '6.rkL'8, ' F.LlkN? Ethanol. seeEthyl alcohol ZE?,F,Z]*g+ 2-Ethoxyethanol(EGEE)[ l0-80-5] 18 sk 2-LF,+LW 2-Ethoxyethylacetate(EGEEA) u I I -15-91 27 SK B*K-2-.FTBZAE Ethylacetate [141-78-6] 400 1440 HMZAF Elhyl alcohol [64-17-5] l 000 I 880 A4 a+*i TWA STEL Ceiling Remrrks ChemicalICAS#J fr+81'jt|f6 EgRffit&t€ ftH&ffilF@ ,t?4,fl, ppm mglml ppm mglm' ppm mglmt l6;t

Ethylbenzene[00-41-4] 100 434 125 543 L+ Ethylbutyl ketone[06'35-4] 15 350 z+ rE+lAlil SK.A4 Ethylenediamine[107-15-3] l0 L -t(q, t0 @,A4 Ethylene-'F\IU.Lffidichloride n07-06-21

EthyleneglycolU07-21-11

Vapourand mist 100 A.4 *F.&* \]T! Ethylene glycol dimethyl ethet see ^, 2-Dimethoxyethane..ry ..Ll L .w *m . a r 2_ !i.E4{i Ethylene glycol monobutyl ethet sec 2-Butoxyethanol z .{+ f ES+ F.2-T n {affi Ethyleneglycolmonoethllelhcracelate. see-tr2-Ethoxyethyl acetate a -z4asAsmEE,-R2-zgr.4ffim LEE Ethylene glycol monoethyl ether, see 2-Ethoxyethanol 1, .w L+N!. F-2-Lfl+Lr? Ethylene glycol monomethyl ether acetate, see2-Methoxyethyl acetate Z'-A+-F/JBTE$fi4AE. E 2.ryF,AAfiAq LEE TWA STEL Ceiling Cht:mitalICAS#J WE+!]E EgREIRIH ftHFffiljVlh Remarks lL4,n pptu nglur ppm mglml pprn mglm' lfr iI

Ethylene glycol moromethyl ether, sec 2-Methoxyethanol e_-tr _F+aas, n2_t11F":*zw Ethllene oxide[5-21-8] 1.8 - @.A2 LtfrtLg. Ethyl ether[60-29-7] I 210 I 520 .W Ethyl glycol acetate, see 2-Ethoxyethyl acetate L+L .EPAq{9,.. EAEAq-2-Ln+LBE .Dichloroethane Ethylidene chloride, sce'.F"L\iI , I LY.-fl, F-l ' r- Ethylmercaptan[75-08-l] 0.5 1.3 tJ Lrhw r>) Ethyl methylether [5406701 N,E. ZITF+AS Ethyl methrvl ketone, see Methyl ct\l ketone Z4ry4trl{lij, -F,lAFI Ethylpropionate[105373] N.E. rtmaEE Fluorides, as F 2.5 AlLflt 't)).H'n\F.H. Fluorine[7782-41-4] 1.6 3.1 *L Formalde\de [50-00-0] Fffi Fbrmalin.see Fbrmaldehyde iFffi,E,i{., ( Ht9fzk)' F,flSf Formicacid[6'{-18-6] ffim,(Fm) TWA STEL Ceiling Remwks Chamical ICAS#] fltE+ltE trgEEWtr RHRffiWIE ILryfi ppm mgtm' ppm mgtffi' ppm mglmj lffiit

2-Furaldehyde,seeFurfural {Rffi'trg,{rdr+ll} SK,A.3 Furfural[98-01-1] 7.9 14ffiryfit SK Furfuryl alcohol[98-00-0] t0 15 60 &gF,([irrHFA*) Gasolinc[8006-61-9] I 480 iSiH 0.2 Sen Glutaralddyde[1I l-30-8) 0.05 ri -fi.t Glycol monoethylether, see 2-Ethoxyethanol L-W 'L48ft'H!-LF,+Lr'E t\J Gypsum,see Calcium sulphate EE' H-diAqf,J Hcptane[42-82-5] R'\k (n-Heptane) (rE,F'fi ) 2-Heptanongsee Methyl n-amylketone RAI'l-t2l'Hri +trrt# FEl-'l 3-Heptanone,seeEthyl butyl ketone RnFl-t3],-trz4 r+trAlil Hexamethylenediisocyanate[822-06-0] 0.034 Sen ^''tFJS.!qF,mA" Hexane[ 10-54-3] -\i, n-Hexane 70 )L-Nn Otherisomers t'760 1000 3500 +.i0^7+fiqs

TWA STEL ,TigRffiIFE Ceiling ChernicalICAS#] ffiErfrr! F'tEFEIWE Rernarks {!.ryfr ppm mglm' ppm mglm' ppm mgl l#;]

2-Hexanone, seeMethyl n-butyl ketone -Ald-t2],E.tirETET4HAE Hexone,seeMethylisobutyl ketone EdAl'l , tl,F+ql 4fFEl4 Hydrazine[302-01-2] 0.01 0.013 @,A'3,Sk ,!lf Hydrochloric acid, seeHydrogen chloride ffim, F,fi.ftfi Hydrofluoric acid" seeHydrogen fluodde 6fim,_Effi,fra Hydrogenu333-74-01 SimpleAsphyxiant 41 +ttry'Y++,,H.Vtit Hydrogencl. oride[7647-01-0] 7.5 fita Hydrosencvanide[74-90-81] 5Sk

Hvdroscnqanide.sallsol.seeCranides fllrkiR .'natuN\? Hrdrosen fluuride [?664-]g-ll. as F 2.6 Fft;i.f{tr4-r"eH Hydrogenperoxidel7722-84-ll 1.5 7@+t I6s1 HvdrosensulDhideI7783-06-41 t0 t4 15 2l tltltFi Hvdroquinone 2l-l l -91l FiEc; +J+ r$ 2, 2'-Iminodi (ethylamine), see Diethylene triamine 2 . z'-l,i.H(EaB.ffi.Jt a1S:n TWA STEL Ceiling fl+F.I'ltffi EWRffiIFIH R'EFEWH Remarks Chewiul ICAS#] 'f# ftryffi ppm mglm' Ppm mgtnl' ppm mglmt it

0.1 lodine[7553-56-2] fim A4 Iron oxidefume (Fe,O,)[309-37-1],asFe 5 ,.F\lLffi'E#,UAH€H Isocyanates,all (as-NCO) 0.02 0.07 Sen -qAmn"'. &fdH l{ q (-NCo)F H 5 A3 Isophorone[78-59-1] Ei4ffiAF] NE, Isoprene[78795] Te J)a-',,11i Isopropylacetate [1 08-21-4] 250 I 040 310 | 290 A*MF.trAE SK Isopropylalcohol [67-63-0] 400 983 500 | 230 RL\AF Isopropylbenzene,seeCumene qtr/= ,_Rtfi,t# N.E. lsopropyl formate[625558] +TAqEtrPJF Kaolin[332-58-7] E{Ft Respirabledust r,lIlX/\t{tr Lead inorganicdusts& lumes Referto Code of [7439-92-1], Practicefor Control of w,NI&#..fsE)L'tr# lead at work 4lrttHfrillfrffigiZr ,ff+q|] Lead alkyls, seeTetraethyl lcad & TetramethyJlead \i'49'. ' Hl\lLgil9vlq9.j TWA STEL Ceiling Chenical [CAS#] flnE+fita 'EgFffiI'F,IE RAFEfFtr Remarks fl.ry'fr lpn mgln' ppm mglm3 ppm mglm3 {6;}

LeadarsenateP784-4091,asPbHAsO., 0.15 fHA€fo' , tll PbHAsO,EH Leadchromate[7758-97-6], s6aagi asPb 0.05 @,A2 t).^ltg,iaH asCr 0.012 @,A2 D)Hl*"'H Limestole, seeCalcium carbonate Elr.+,HbfrW.ffi L. P G. (Liquified petroleumgas) [68476-85-7] I 000 1800 Asphyxiation 6ihfi iEtrtIeIu{€.H. tJ Magnesiumoxidefume U309-48-41 l0 F,ltf**s# Malathion[121-?5-5] 10 SK,A4 .F+nffi,ffi Maleicacid[110167] N.E. nFTrifrlAt ' ( ,Hi*m) Maleic anhldride [108-31-6] 0.25 1.0 lrtFTtff-fieffi' ( ,F,./xAtaf) Manganese[7439-96-5], asMn ffr ' rz}JlfdEH Elemental and inorganic compounds ffi&Rt.g..ttt+h Manganese dioxide, seeManganese -F|Lffi,Nffi Marble,seeCalciumcarbonate '.tLa, Hr#.w.tE TWA STEL Ceililg Remqrks Chemical ICAS#] n'lE f Y4fH EfTEffiW{H RFtRffitWE ILryffi lp nglm' ppm mglm' f r'm mglm' llHii

Mercurouschloride, see Mercury AiLF,Iii ' F.7.(tE Mercury[7439-9?-61,as Hg *(zKffir'UHTIEH Alkyl compounds 0.01 0.03 SK r;;&|u.af/)r Aryl compounds 0,1 fr+\U.lrt', Inorganic fbrms 0.025 i$,i*qx7n Methacrylicacid[79-41-,1] 10 F+nftr.'fi€ Methane[74-82-8] SimpleAsphyxiant ry'Ei )F|U.ry'Wa,1'Vtfr. Methanethiol, seeMethyl mercaptan F iiiEF , n- Methyl mercaptan Mcthanol, seeMethyl alcohol FFg+,-H,+*A+ 2-Methoxyethanol(EGME) u09-86-41 SK 2-q'it+L[e 2-Methoxycthylacetate(ECMEA) ll10-49-61 SK F*m-2-trfi,+zAii '7 Methyl acetate[79-20-9] 606 5'7 ffiaefla"" Methyl acrylate[96-33-3] SL rrffimqrnE Methyl alcohol [67-56-l] SK ryrtsE+ .TWA STEL Ceiling ChemicalICAS#J trFT.rilfr +EgFEIIFIE 4ia *t*ttt

Methylamine[74-89-5] 5 6.4 15 l9 ryffi Methyl n-amylketone 1110-43-01 50 233 F+cfi4ryEE M€thylbromide[74-83-9] I 3.9 @,sk F4IE 2-Methylbuta-J,3-diene [78795] N.E. 2-F+-1, 3-T-,16 2-Methylbutan-2-ol[75854] N.E. 2-qr4-2-TF Methyln-butyl ketone [591-78-6] 5 20 10 40 sk H+lLT4Fgq Methyl chloride[74-87-3] 50 103 100 20'7 @,sk,44 F4fi Methyl chloroform[7]-55-6] 350 I 910 450 2 460 A4 F*afn Methylenebisphenyl isocyanate (MDI) 0.005 0.051 Sen ll0l -68-81 *rfl19-F-5,maE Methylenechloride [? 5-09-2] 50 t'r'4 (4.43 lrr+rE-fi Methylene--.Fdichloride, see Methylene chloride + FE ' E Methylenechloride Methyl ethylketone (MEK) []8-93-31 200 590 rBF] Methyl ethyl ketone peroxide (MEKP) Il l lR-t 1-z1l €qiir+iZa+su TWA STEL Ceiling Chmtical tl+81.frH nwFEMra &HREFPfE Remarks ICAS#] 'i6;t 'fl:4fr ppn mgtm' ppm mghn' ppm mglmt

Methyl glycol acetate,see2-Methoxyethyl acetate F € Z-FAfi MAH',-Hffi M-2-F fi 4ZAF Methylisobutylketone u08-10-11 75 307 FEq I-+FAI'] Methyl mercaptan [74-93-l] 0.5 ryitia? Methylmethacrylate[80-62-6] 100 4t0 A4 +4trffiMLFAE Methylparathion[298-00-0] 0.2 SK,44 F4:gfiiiL4 2-Mcthylpropan-2-ol,seetert-Butyl alcohol 2-ry+6-2-AF,_B+{J'm+ Methyftdchlorosilane [1 5196l N.E. tr+ - fi6+1i Mineralwoolfiber A4 tHtfiffifE l, 5-Naphthylene diisocyanate, see lsocyanates, all I , 5-a++-EF,mEE,F,gF,mAE'#-f6ffi p-Naphthol351931 N,E. p-+M u Naphthalene[9]-20-3] l0 52 l5 a-Naphthylamine[34327],contatntngless N.E. than l%,p-Naphthylamine a-*,8t, A9it r'%F-#EU p-Naphthylamine[91-59-8]andits salts @,Al, prohibited p-*&&]{ffi TWA STEL Ceiling ChemicalICAS#] frE+jqffi }EgFEfFtr REFffittFtr Remarks Itry,F, ppm mglms ppnl mglm, ppm mgtm Wia

Nickel w Elemental/metal 1.5 *na,/+tr [7,140-02-0) A5 Solublecompounds, as Ni 0.1 A4 F{W,W.tt6Hn Insolublecompounds, as Ni 02. AI ;FiltEItlU.hUn Nitric acid l769'7-1'l-21 5.2 10 6Hm Nitric oxide 25 3t -fl1r_.n [10102-43-9]

Nitrobenzene[98-95-3] I 5 sk, A.3 o'\ fti+^ Nitrocellulose[9004700] N.E. fiH|tffi'��ttx ;l-Nitrodiphenyl[92-93-3]and its salts @.A2, Sk, prohibited 4-6H+{if*&4EF *n Nitrogendioxide[10102-44-0] 3 5.6 9.4 -- 44 .Y\lrtt Nitrous oxide[10024-97-2] 50 90 -1'4 F,it+a n-NonaneU11-84-21 200 I 050 -I )')ti OctaneflIi-65-91 300 1.t00 375 1750 +M Oil mist, mineral 5 10 G frF+ttiEffi TWA STEL Ceiling ChemicalICAS# J fl+E+fiE iEWFffiIW.IH RHRffiltRffi Remurks ll:41l'A ppm mglmr ppm mgtm' prm l gtm tffi 6t

Oleum, sce sulphudc acid ?fEIfiM,-RffiAT Orthophosphoric acid, seePhosphoric acid rtffim' tilffiAq Oxalicacid |44-62-71 7 tr\E Oxalic acid. salts of N.E. - 7 {6tFE

Ozone [0028- 15-6]

Heavy work 0.05 0.1 EB-WhrlF Moderate work 0.08 0.16 ',F€€Slrrif Light work 0.1 o.2 'lEe.-ffiiIif Paraldehyde!236371 N,E. B{#'(=FZS{) Paraffin wax lume [8002-14-21 fiiHEF Paraquat[4685-14-7] Eeffi Total dust 0.5 +#)r+ Respirablefraction 0.1 nIrx *llrI Paraquatdichloride [910425] E+tfr-alt+h Respirabledust Flry7^iv.E, TWA STEL Ceiling ChemicalICAS#J WE+ftl€ &gFi4\l'RlE &BRffiFFfA Remarks It4fr ppm mglm' ppm mglm' PPnt mgtm' lHaa

Particulatepolycyclicaromatic hydrocarbons(PPAH),see Coal tar pitchvolatiles +#fr E h\'tr1fi.+n,n RRt ttt ffi H ffi '*W Palticulates Not Otherwise Classified (PNOC) D J!{&**qr}#'ft+n PCBs,seeChlorodiphenyls 9AW+,nF\W# Pentachlorophenol[87-86-5] 0.5 @,sk, A3 rq0,) PentaneU09-66-01 t'170

6 ft,ffi Pentanol,all isomerswith exceptionof - N.E. tert-Pentanol ,qBi.' tfAq,ffif,g, 'f,{,qFhtl' tert-Pentanol N.E. ,l{,q4+ Pentan-3-one, seeDiethyl ketone riAlil-t3l, F,--.aAl4 Pentyl acetate, seen-Amyl acetate Zmrtttn"'' F,iEEfi mrtAE Peraceticacid[79210] N.E. il6L{6. Perchloricacid[7601903] N.E. Efm Perchloroethyleneu27-l 8-41 25 @,A3 wF"z-'ffi, (ffiFtL.l.ft) TWA STEL Ceiling Chenical tttE+f4lA EPJFffiIRIE &HREIJFA Rematks ICAS#J '{#it It 41fi ppm mglmr ppm mglm, ppm mglm

Petroleumdistillatesand Coal tar distillates,seeGasoline, Stoddard solvent,VM&Pnaphtha dffi**ffi+n)j,'RRtfr.+-ffil,h,-F,trid' F ffi€rdA{' iFif Fl€& FpHr].r+lE,qsru Phenol[08-95-2] 19 SK &i o-Phenylenediamine [95-54-5] 0.1 @,A3 flr# ,ti m-Phenylenediamine [108-45-2] 0.1 A4 FflIF:fiF p-Phenylenediamine[106-50-3] 0.1 A4 at F-t( Phenylethylene,seeStyrene, monomer 42ffi , -B Styrene, lf ffi Phosgene 0.1 0.40 xtu" [75-44-5] Phosphine[7803-51-2] 0.3 0.42 1.4 wIu.F" Phosphoricacid[7664-38-2] I 3 ffim Phosphorus(red)177231401 \TE frffi Phosphorus(yellow)11'723-14-01 0.02 0.1 E{rt Phosphoruspentachloride[0026-l3-8] 0.1 0.85 irfi'f Let Phosphoruspentoxidell 3145631 N.E. rt.F.It--t/+ TWA STEL Ceiling ChemiutlICAS#] F+E+ttrH trgEEWH REREfFtr Remarks ftryffi ppm mgtm' ppm mglm' ppm mgtm t#;t

Phosphorustrichlotide 19-12-21 0.2 Ll 0.5 2.8 -FiLffi l'17 Polychlorinatedbiphenyls(PCB). seeChlorodiphenyls tfrW+' nFtffi# Polychlorobiphenyl s,seeChlorodiphenyls 444fr+ ' HF1"ffi* Portlandcement [65997-l 5-1] )Et*tfizjtlE Totaldust l0 D ++i,E Rcspirabledust 3 5 FJlt-l'frt,E Potassiumchlorate[3811049] N.E. FMfF Potassium chromate, see Chromium (VI) compounds ffiWN'F,ffi(v\lLhvn Potassium cyanide, see Cyanides Fi..t,Y,flt, tua"\t+h Potassium dichromate, see Chromium (VI) compounds E$$$$$8&tr,F"ffi(vDIU.l;+h Potassiumfluoride,seeFluorides F,tt"ffi' F-tu|V.ryn Potassium fluorosilicate, see Fluorides ffihEWfl, ilF.IU.W Potasiumhydroxidell3l0-58-31 Et +r"tIftf TWA STEL Ceiling Chernical[CAS#] E+E+fiIE +e.PiREM{A &EiEffilWE Remqrks 'f1.4fr ppm mgtnl ppm mglm' rpm mgtm lHii

Potassiumnitdre N.E, r',iiHmds [7758090] Potassiumperchloratel717 81 471 N.E. HFMtr Potassrumpermanganate, see Manganese compounds HoofrAt$$$$$fl, nffi1L6f4 Potassium salt of Dichloroisocyanurrc N.E. acid 122442151 .FrEfiRA:tffffii Prccipitatedsilica, see Silica Amorphous tiirBti+E'tlen -)t # Fa+iH 5 n-Propanol, seen-Propyl alcohol JE6H, JIEI+A? Propan- l-ol, seen-Propyl alcohol E$i'_tl], _HrjEEf Propan-2-ol. seelsopropyl alcohol Fn+-l2l' F,EAls+ 2-Propen-l-o1, seeAllyl alcohol 2-Erl6$i-trl,it rd,,Fr,E? n-Propylalcohol [71-23-8] 6t4 SK t^i+a+ Propylene glycol monomethyl ether 553 [107-e8-2]--ts+- rrj F4AS Pyridine[110-86-1] lttlrl Quartz,sceSilica Crystalline a+, Hh+h ffifi,fq TWA STEL Ceiling Chemical ICAS#] E+E+ttffi trwEEtwE RBREIWE Remarks II,EFffi ppm mglmr ppm mgtm' ppm mglm' ffiit

Resorcinol,seem-Dihydroxybenzene ffirHBl'E,tif,*:M Rubbersolvent (Naphtha) [8030-30-6] 400 ffiEziASi(a,ctriH ) Silica Amorphous r&.a\ -F"l?.t+)-1Fffiftffi Totaldust l0 +f;@ Respirabledust 3 FIr&,\1ittr Silica Crystalline A hE41| -F,|tF+ )-fFfiH tJ Cristobalite[ 4,X64-46-1] nE9t total dust +*tE respirabledust EIaB.^at.i.E Quartz[14808-60-7] hfr total dust +#Jffi respirabledust trlr&,\'iff,8 Silica,fused r+n,frA{a[60676-86-0] respirabledust qpfr,L:r,^E TWA STEL Ceiling Chenical ICAS# ] wElzjrffi EPiFEWtr &,ri&ffiltEtr Remarks lL4H ppm mglm' ppm mgtm ppm mgtm' tffi ni:

Tridyrite [ 5468-32-3] ffi714.. totaldust efi.E rcspirable'M.Edust 0.05 ilW. Tripoli[1317-e5-9] !a€ar respirabledust 0.1 of containedrespirable 4!&,\ff,@ quartz ffitneEE\nIFN^6 4 Siliconcarbide [409-21-2] A 6frtti+ Total dust l0 D, A.4 +#,8 Respirablcdusl 3 nJ|rEUil E Silver[7440-22-4] TR Metal 0.1

Solublecomoounds.as As 0.01 ',)ifrlt!+7-.l1EfrFg Silver nitrate, see Silver soluble compounds fiHM$R, R'RE],E{LA1Z Sodiumchlorate[7775099] N.E. fim,ft Sodium cyanide, seeCyanides Ftltffi , nEtIL+k Sodium dichromatq seeChromium (VI) compounds TWA STEL Ceiling ChemicalICAS#J E+E+YtlH tFgEEtt7lA EHREIFIE Remarks fLPfr p?m nglnf ppm mglm' pfm tgltn' lFtI

Sodiumdithionite[7775146] NE. ie -$ti,Aa$d Sodium lluoride, seeFluoride F"nm'nalL+n Sodium fluorosilicate, sec Fluoride FrnlKlfr,F-FtlL*h Sodium hydrosulphite. see Sodium-,li,i,haq$tu dithionite IE{i,AAeift' ( {+pft{,i)' _F.€ Sodiumhydroxide[ 3I 0-73-2] 6rfi'Itiilr Sodiumhypochlorite I529] N.E. 5 [768 5 itfiA�e$il sodiumnitrite [7632000] N.E, siilm$& Sodiumpercblorate[7601890] N.E, HfiFT$'{ Sodiumperoxide!3136061 N.E. @fi.frift Sodium salt of dichloroisocyanuric acid [2893789] N.E. -fiEg..EAA$nffi Sodiumsulphidc [ 3131i22] N.E. ilrl'iL$dt Stannicchloridc,sce Tin inorganic sompounds 'F"1U.ffi.F-ffiMW.|L+Y) TWA STEL Ceiling ChemicalICAS#] E+A+fr8 XEgFffifRtr &BREI1RIH Remarks '|t4fr ppm ntglm3 ppm mglml pPm ntgtm ffg dt

Starch[9005-25-8] r&t) Total dust 10 +v-\B Respirabledust 3 4tt[&x't#:!.E Stearates l0 K iq,qFA€EF Stoddardsolvent[8052-41-3] 100 525 e@iEi6A{ Styrene.monomer[100-42-5] 20 85 t70 @,A4 +erfi' tr€H A Succinicanhydride [108305] N,E. rfi]fffi Sulphur- dioxide [7446-09-5] 5.2 t3 9,1u.ffi. Sulphuricacid [7664-93-9] 1 3 A2 ihm Sulphurylchloride [7791255] N.E. itiE4ifi SvntheticVitreous Fibers ans,fr4*iffi*c continous filament glassftbre I f/ml A4 !nrBr,frfF (or 4) 5 mg/ml slasswool fibre I 17mL A3 &iqffiffi,*E rock wool fibre I f/ml Et?,ffitc slag wool fibre I f/ml 6Htr6H#frfiF TWA STEL Ceiling Chemit:alICAS#J wE+ltH *rtgRffilt{lh RHEEIWIE Remqrks It 4,H ppm mglmr ppm mglm ppm mglm' lH;+

specialDurpose-glassfibre I f/ml- t+f6niisffi## Talc (containing no asbestosfibers) [14807-96-6] iH.7i(4Aaffiffif& ) Respirabledust nl$&^l,ttr Talc(containingasbestosfibers), seeAsbestos 2 @,asbestosOEL-TWA wE(A6t?,ffiffi) ,-F.AtH 4FREtflffiE+lrtr TDI, seeToluene-2, 4-diisocyanate'EF.MAS TDI , F,II+-2 , 4. l, l, 2, 2-Tetrachloroethane[79-34-5] @,sk, ,A.3 o\ t't'2,2-w:a\L\i Tetrachloroethylenq seePerchloroethylene w€"L'ffi' -RrBFrZi.ft Tetrachloromethane,see Carbontetrachloride Uul{FIIiJffi, HV]F\|Z.M Tetraethyllead [78-00-2], asPb 0.1 .- qL A1 P!L?*, N)N*EH Tetrahydroluran[ 09-99-9] 590 u!16i4rH Tetramethyllead[75-74-1],asPb 0.15 sk E+flJ , I-I4SA€H Thionylchloride[77I 9-09-7] 4.9 STiIAfifr Tin[7440-31-5] ffi TWA STEL Ceiling ChemiculICAS# | FtEYjt{rt trgEffi[F/E RHFEIIFIE Remarks 11,4ffi ppm mglm' ppm mglftr ppnt mgtm tffinx

Metal

Oxide & inorganic compounds, except SnH", as Sn 's"ltryneffiffi1L67+n' WaAtLffi tl, U,frtrJAH' Orsanic comoounds. as Sn SK,A.4 E-WkA+k,UF,&AH Titanium dioxide[ 13463-67-1] rfi.ftct Total dust 10 +{J},4! Respirabledust 3 s "JFll^1i4..8 -l Titanium tetrachloride[7550450] N.E. t,LtfiiLqi o-Tolidine[1l9-93-7] @,A3, Sk fr$[tftq+tr4 Toluene[108-88-3] 50 188 SK,A4 F+ (TDl) 0.005 0.036 0.02 0.l,t @,Sen,,A4 Toluene-2,4-diisocyanate--R-AmAEE [584-84-9] F*-2 , 4- (rDl) ( --RAmFaPcE) o-Toluidine[95-53-4] 2 8.8 @,,{3,SK HlF j*,tt Toluol,seeToluene Ft, F-Toluene 1.1, l -Trichloroethane,see Methyl chloroform I r l- .{,Zti . ,F-Fq*rlry TWA STEL Ceiling Chemical ICAS#] tr+Ef IJ LH EgREWtr R'HFEWE Remarks tL,effi ppm mglm' ppm mgrm' ppm mglm' ffi;+

1, l. 2-Trichloroethane[79-00-5] 10 55 SK,,A.4 1'1'2-=FLrli Trichloroethylene[79-01-6] 100 537 @,As ...F,L'ffi Tiichlorofluoromethafie [1 5-69-4] l 000 5 620 A4 -,-*t *t + t{n Trichloromethane,seeChloroform -:firflH , -tl,F'ft (methyl) Trichloro-a(F+)qr6+Hsjlane[75796] N.E. Trichlorosilane -FHT+H [10025782] N.E, A '7 oo l, l, 2-Trichloro-1. 2, 2tdfluoroethane[76-13-l] l 000 6'70 1250 9 590 A4 r. r,2--,F" , t,2,2-=,Ft"Lffi. Tri-o-cresylphosphate,see Triorthocresylphosphate ffim '#$F*AF ' E Triorthocresylphosphate Tridymite,seeSilica..^Crystalline fif,64, F,i+A-##H Triethylamine!21-44-81 4.t SK,A4 :.LtE Trimethylamine 15 -F& [75-50-3] - Trimethyl-,H++benzene [2555 | l3-'7] 3, 5, 5-Trimethylcyclohex-2-enone, seeIsophorone 3, 5' 5-=F#€- -2-'16Eldl'JtE{*fr{El4 TWA S'IEL Ceiling Chemical[CAS#J il,fF+ttffi trg&Et'FE &ERffiWtr Remarks ftry,H' ppn mglm' ppm mgtm pptn mgtm Eflaa

2,4. 6-Tdmethyl-1,3, 5-Trioxan, seeparaldehyde 2 ' 4,6--FE.-1 , 3 ' 5- '.r*H ' -EEI]AT Triorthocresylphosphate[78-30-8] SK,44 4{A=Hj+r+EE Tripoli, sceSilica Crystalline E+#+.,F.E{ii-ff#fftH Tri-o-tolylphosphate.scc Triorthocres)'lphosphate -#Ll.rt+&ffirqE,R Triorthocresylphosphate

A Turpentine[8006-6,1-2] 556 {a\FfiH VanadiumPenroridc.a, \ O llll4-62-ll fr.Fr,lL .trt ' tlV,o.H Respirabledust & fume 0.05 A4 "Jtll^iik.E]&.M'l* Vegctableoil rrists 10 J lE+\il!# Vinylchlodde[75-01-4] 13 @, Ll ALffi,I Z*6+F) VarnishMakers'& Printers'(VM & P) 1370 A3 Naphtha[8032-32-4] i€inBl6&FrrfiUH6,!ffit W.-lding fumes (NOC) 5 'tri+'E* | +si$/,trfF) White spirit. see Stoddard solvent liiHi6ql' Jil,ElEl€i6Al STEL Cciling Chemicul ICAS#] fr+E+tr{E frgFE[FH eBEffiWE Remarks ftryH ?pm mglm' ppm mglm' ppm mglm, '{#;n

Wood dust ^fitr Certain hard poods as beech & oak I - Sen, Al +{4iE/(lEilr€i4&ffi6J Soft wood 5 l0 +r4 Xylene[ 330-20-7:95-47-6;108-38-3: - 106-42-31(o-,m-,p-isomers) 100 434 150 651 ,{4 F+ (Ft64[' f"]' fi^E+tr€g) Xylenol --tF*8,)[300716] N.E.

Zinc, seeZinc oxide (-^ f+ , HFtItt+ Zinc ehloride"see Tinc chloride fume F,lU.f+, Rtsl1tfrWE Zinc chloridefume | 2 attfrtr# [7646-85-71 Zinc-ch-ro-mIgs[13J30-65-9;11103-86-9: 0.01 @,Al 37300-23-51,asCr ffrM�.*, r,rF,i&EH Zinc oxide[ 314-13-2] fi'1t$+ Dust l0 D ryj'E fume 5 l0 ,Effi UsefulInformation If you wish to enquireabout this guidebookor requireadvice on occupational safetyand health,you can contactthe OccupationalSafety and Health Branch through: Telephone : 2559229'7 (auto-recording afteroffrcehours) Fax : 2915l4l0 E-mail : [email protected] lnlbrmation on the servicesoffered by the Labour Department and on major labour legislationcan alsobefound by visitingour Home Pageon thelnternet. Addressof our Home Pageis http://www.info.gov.hk/labour.