Monitoring strategies for toxic substances

Transcription

1 Health ad Safety Moitorig strategies for toxic substaces This is a free-to-dowload, web-friedly versio of HSG173 (Secod editio, published 2006). This versio has bee adapted for olie use from HSE s curret prited versio. You ca buy the book at ad most good bookshops. ISBN Price 6.95 This guidace highlights procedures i how to ivestigate employee exposure to toxic substaces through ihalatio that may be hazardous to health ad how to cotrol the ature of ad extet to this exposure. It is aimed at all employers i geeral ad at all health ad safety professioals where it ca be a useful itroductio to the subject as well as esurig that you are doig eough to comply with the law. It also targets o-specialists i order to help with gaiig a iitial uderstadig i order to be able to ask questios ad seek advice from cosultats ad others. HSE Books Page 1 of 23

2 Health ad Safety Crow copyright 2006 First published 1997 Secod editio 2006 ISBN All rights reserved. No part of this publicatio may be reproduced, stored i a retrieval system, or trasmitted i ay form or by ay meas (electroic, mechaical, photocopyig, recordig or otherwise) without the prior writte permissio of the copyright ower. Applicatios for reproductio should be made i writig to: The Office of Public Sector Iformatio, Iformatio Policy Team, Kew, Richmod, Surrey TW9 4DU or [email protected] This Code has bee approved by the Health ad Safety, with the coset of the Secretary of State. It gives practical advice o how to comply with the law. If you follow the advice you will be doig eough to comply with the law i respect of those specific matters o which the Code gives advice. You may use alterative methods to those set out i the Code i order to comply with the law. However, the Code has a special legal status. If you are prosecuted for breach of health ad safety law, ad it is proved that you did ot follow the relevat provisios of the Code, you will eed to show that you have complied with the law i some other way or a Court will fid you at fault. Page 2 of 23

3 Health ad Safety Cotets Itroductio 4 Legislative requiremets 5 Exposure limits 5 Ihalatio exposure moitorig 6 Why you should develop a moitorig strategy 6 Persoal moitorig 6 Fixed place moitorig 7 Approaches to ihalatio exposure assessmet ad moitorig 7 Iitial appraisal 10 Basic survey 11 Detailed survey 12 Reappraisal 13 Routie moitorig 13 Iterpretatio of results 14 Compliace testig 15 Appedix 1: Factors ifluecig airbore cotamiat cocetratios 16 Appedix 2: Variables ifluecig the desig of moitorig strategies 17 Appedix 3: Core iformatio 20 Refereces 21 Further iformatio 23 Moitorig strategies for toxic substaces Page 3 of 23

4 Health ad Safety Moitorig strategies for toxic substaces This guidace is issued by the Health ad Safety. Followig the guidace is ot compulsory ad you are free to take other actio. But if you do follow the guidace you will ormally be doig eough to comply with the law. Health ad safety ispectors seek to secure compliace with the law ad may refer to this guidace as illustratig good practice. Itroductio 1 This guidace is addressed primarily to employers. First published as EH42, it was the revised to make it more accessible to o-specialists so that they ca use it as a itroductio to the desig of ihalatio exposure moitorig strategies. 2 You ca use these procedures to ivestigate employee exposure, by ihalatio, to substaces hazardous to health. They will help you ivestigate the ature, extet ad cotrol of employee exposure. 3 The guidace will also help you to uderstad ad ask questios about ay iformatio or advice that you may receive from cosultats ad others. 4 Health ad safety professioals may also use this guidace as a itroductio to the subject. For more detailed iformatio o specific issues, see Refereces. 5 The Cotrol of Substaces Hazardous to Health Regulatios 2002 (as ameded) (COSHH), 1 regulatio 2, states that substaces ad preparatios (mixtures of two or more substaces) hazardous to health iclude: substaces i Part 1 of the Approved supply list 2 as dagerous for supply withi the meaig of the Chemicals (Hazard Iformatio ad Packagig for Supply) Regulatios 2002 (CHIP) 3 ad for which a idicatio of dager specified for the substace is very toxic, toxic, harmful, corrosive or irritat; substaces with a workplace exposure limit (WEL); biological agets; dusts of ay kid i substatial cocetratios; ad ay substace that creates a risk to health because of chemical or toxicological properties. 6 The iformatio i this guidace is ot suitable for: assessig exposure to micro-orgaisms; assessig exposure from o-ihalatio routes (ie ski absorptio ad igestio); assessig safety issues such as flammability, explosive hazards ad asphyxiats; ad measurig emissios of volatile orgaic compouds (VOCs) uder the Evirometal Protectio Act You eed to be aware that substaces hazardous to health ca eter the body by igestio (ie swallowig the substace) ad ski absorptio (ie through the ski) as well as by ihalatio. This meas that i some situatios you may also eed to measure the total amout of a substace that has etered a employee s body. Moitorig strategies for toxic substaces Page 4 of 23

5 Health ad Safety This is doe usig a techique called biological moitorig. 8 Biological moitorig is outside the scope of this guidace. For further iformatio about biological moitorig, see Biological moitorig i the workplace: A guide to its practical applicatio to chemical exposure. 4 9 There are specific legislative requiremets for lead, asbestos ad respirable dust i mies. The priciples described i this guidace apply equally to moitorig ihalatio exposure to these substaces. Legislative requiremets 10 The pricipal regulatios goverig substaces hazardous to health are the COSHH Regulatios. The cetral requiremets are: regulatio 6(1) - you should carry out a suitable ad sufficiet assessmet of the risks to the health of your employees ad ay other perso who may be affected by your work, if they are exposed to substaces hazardous to health; regulatio 7(1) - you should esure that exposure is preveted or, whe this is ot reasoably practicable, adequately cotrolled. 11 If you comply with COSHH regulatio 6(1) you have fulfilled your duties uder regulatio 3 of the Maagemet of Health ad Safety at Work Regulatios Remember, this oly applies to substaces hazardous to health, eg ot physical hazards such as oise, radiatio ad machiery guardig. You will eed to assess ad cotrol ay physical hazards ad risks separately. 12 The legal requiremet for moitorig ihalatio exposure is give i regulatio 10 of the COSHH Regulatios. It requires you to carry out moitorig if: it is ot immediately obvious to you whether there is a risk to the health of your employees; ad there is a suitable procedure which you ca use to measure exposure. 13 Regulatio 10 is clarified i detail i the COSHH Approved Code of Practice. 6 This states that moitorig is required whe: failure or deterioratio of the cotrol measures could result i a serious health effect; whe measuremet is eeded to esure a WEL or ay self-imposed (i-house) workig stadard is ot exceeded; or as a additioal check o the effectiveess of ay cotrol measures provided i accordace with regulatio 7, ad always i the case of the substaces or processes specified i Schedule 5 to the Regulatios; whe ay chage occurs i the coditios affectig employees exposure which could mea that adequate cotrol is o loger beig maitaied. Exposure limits 14 A umber of substaces hazardous to health i the workplace have bee assiged Workplace Exposure Limits (WELs). These are averaged over eight-hour or 15-miute referece periods. 15 A WEL is the maximum cocetratio of a airbore substace averaged over Moitorig strategies for toxic substaces Page 5 of 23

6 Health ad Safety a referece period, to which employees may be exposed by ihalatio. 16 WELs should ot be cosidered a hard ad fast lie betwee safe ad usafe. The priciples of good cotrol practice (COSHH 2002, Schedule 2A), if applied correctly, should esure exposures are below ay relevat WEL. 17 To comply with the requiremets i COSHH regulatio 7(7)(c) (exposure to asthmages ad carcioges) to reduce exposure so far as is reasoably practicable, employers may eed to carry out a programme of air moitorig i accordace with regulatio 10. This will be geerally ecessary uless the risk assessmet shows the exposure is ulikely to ever exceed the WEL. 18 The majority of substaces used i idustry have ot bee give WELs, but this does ot mea that they are safe. I these circumstaces you eed to esure that exposure is cotrolled to a level to which early all the workig populatio could be exposed day after day, without adverse effects o their health. 19 To judge whether there is a risk to the health of your employees i these circumstaces, you may be able to use limits produced by other bodies, such as Guide to occupatioal exposure values from the America Coferece of Govermetal Idustrial Hygieists. I all cases, the priciples of good cotrol practice should be applied i the first istace. 20 You ca also use the iformatio provided by your maufacturer or supplier, uder the Chemicals (Hazard Iformatio ad Packagig for Supply) Regulatios 2002, 3 to set i-house stadards. For further iformatio about settig i-house stadards, see Refereces. Ihalatio exposure moitorig Why you should develop a moitorig strategy 21 As a employer, you may wish to develop a moitorig strategy. There are a umber of good reasos to do this, icludig: health risk assessmet; compliace with WELs; to help towards the desig of exposure cotrol measures; checkig the effectiveess of your cotrol measures; iformig your employees of the patter of exposure ad level of risk; to idicate the eed for health surveillace; establishig i-house exposure stadards, where ecessary; for isurace purposes; ad to cotribute to epidemiological studies. Persoal moitorig 22 Measurig your employees persoal exposure, by ihalatio, to substaces hazardous to health is ot the same as measurig the amout at a particular fixed site i the workplace. Fixed sites ca be either: at the source of emissio of a substace hazardous to health; or at aother area i the workplace, away from the source. Moitorig strategies for toxic substaces Page 6 of 23

7 Health ad Safety 23 Persoal moitorig is used to establish the cocetratio of a airbore substace withi the employee s breathig zoe. This is explaied i more detail i Appedix 2, paragraphs With the exceptio of viyl chloride, WELs relate to persoal exposure. 24 You will eed to cosider whether persoal exposure moitorig will be useful whe assessig the risks to your employees from workig with substaces hazardous to health. 25 Remember, exposure moitorig is ot a alterative to the adequate cotrol of exposure ad programmes ca be time-cosumig, labour-itesive ad expesive. Therefore, it is importat that you establish: a clear eed for moitorig; a uderstadig of the factors likely to ifluece the exposure; ad a strategy which is fit for the purpose. Fixed place moitorig 26 Most WELs refer to persoal exposures. You ca also use fixed place or static moitorig to obtai iformatio o the likely sources cotributig to the exposure. However, fixed place moitorig does ot usually reflect the amout that oe of your employees could breathe i, which determies the risk to health. 27 You may take fixed place samples: to check the effectiveess of your cotrol measures; to idetify emissio sources; to determie backgroud workplace cotamiat cocetratios; if there are o suitable persoal moitorig methods available; whe wearig persoal moitorig equipmet may itroduce additioal hazards; whe cotiuous moitorig alarm systems are istalled; ad i the case of viyl chloride. Approaches to ihalatio exposure assessmet ad moitorig 28 Because of variatios i plat, process, work ad other coditios it is difficult to draw coclusios about log-term exposure patters o the basis of a sigle measuremet of exposure at oe poit i time (see Appedices 1 ad 2). 29 You will eed to make sure that the moitorig strategy you devise ad the way you iterpret the results allows you to draw coclusios with cofidece about the risk to the health of your employees. 30 Exposure moitorig ca be time-cosumig ad expesive. But, if you follow the advice outlied i this guidace you will get the most out of a moitorig exercise, at a reasoable cost. Moitorig strategies for toxic substaces Page 7 of 23

8 Health ad Safety 31 Each stage i the idustrial maufacture ad use of substaces hazardous to health ivolves differet tasks. Each of them ca preset differet exposure coditios. Figures 1a - 1e show how exposure ca vary, ofte over short periods of time, durig a shift. Figure 1a: A exposure patter for a workig shift (8 hours) Figure 1b: Variatios i exposure over a 24-hour period Figure 1c: Daily variatios i shift averages (8-hour time-weighted averages) Moitorig strategies for toxic substaces Page 8 of 23

9 Health ad Safety Figure 1d: Cotiuous moitorig trace (eg pait sprayig showig itermittet ature of job) Figure 1e: 15-miute time-weighted average exposure 32 The desig of a moitorig strategy will be greatly iflueced by the: aims of the survey; ad coditios preseted by the process. 33 The scope of the exposure assessmet will deped o how complicated the process is. However, i may situatios it may be possible to determie the likely level of exposure without takig measuremets. Figure 2 illustrates a structured approach for evaluatig exposure by ihalatio. 34 The followig paragraphs outlie this approach to moitorig ihalatio exposure to substaces hazardous to health. 35 Not every situatio is complex eough to warrat such a structured approach, for example moitorig exposure to solvet vapours durig had paitig i a wellvetilated room. I these situatios you could select or combie differet aspects of the structured approach. Moitorig strategies for toxic substaces Page 9 of 23

10 Health ad Safety Figure 2: A structured approach for assessig exposure to substaces hazardous to health by ihalatio 36 You may cosider combiig aspects of the basic ad detailed surveys. This may ivolve the simultaeous use of smoke tubes, air velocity meters, chemical idicator tubes ad persoal samplig equipmet. 37 Stadards for geeral performace requiremets, for procedures to determie the cocetratio of substaces hazardous to health i workplace air, ca be foud i BS EN 482, Workplace atmospheres - geeral requiremets for the performace of procedures for the measuremet of chemical agets. 9 Iitial appraisal 38 The iitial appraisal is a importat part of the strategy described i Figure 2. It helps you establish the eed for, ad the extet of, exposure moitorig. This will help you to decide o: the hazards; the potetial risks; ad whether more iformatio is eeded (eg do you eed to carry out moitorig to obtai a estimate of the exposure of your employees to substaces hazardous to health?). Moitorig strategies for toxic substaces Page 10 of 23

11 Health ad Safety 39 The first stage of the iitial appraisal requires you to fid out iformatio o a variety of factors, for example: the substace that your employees are exposed to; the hazardous ad physical properties of the substace; the airbore forms of the substace; the processes or operatios where exposures are likely to occur; the umber, type ad positio of the sources from which the substace may be released; which groups of employees are most likely to be exposed; the patter ad duratio of exposure; work practices; the meas by which the release of the substace is cotrolled; whether respiratory protective equipmet ad/or other persoal protective equipmet are wor ad their effectiveess; ad what are the WELs, limits from other bodies or i-house stadards for the substace ivolved. 40 You ca obtai this iformatio from a umber of sources, for example: labels o cotaiers ad packages; maufacturers ad suppliers safety data sheets; HSE publicatios; techical literature from trade associatios; ad past experiece. 41 Whe you have this iformatio, you ca use simple qualitative tests to help you decide whether there may be a risk to the health of your employees, for example: smoke tubes ca illustrate the movemet of air uder the ifluece of draughts, geeral ad local exhaust vetilatio systems, ad show what the effects are; a dust lamp allows you to see very fie airbore particles which are ivisible uder ormal light. This helps you idetify emissio sources ad watch the movemet of airbore dust. Further help o the use of dust lamps ca be foud i HSE s The dust lamp: A simple tool for observig the presece of airbore particles; 10 smell ca also be used as a idicator of cotamiatio. But remember this is a ureliable method. 42 Based o the iformatio collected durig the iitial appraisal you may coclude that the level of exposure, by ihalatio, is acceptable. If this is the case, it might ot be ecessary to carry out exposure moitorig. 43 Remember, the level of exposure of your employees to a substace hazardous to health ca chage. This meas that your iitial assessmet may o loger be valid. You should always be aware of the eed for exposure moitorig. Basic survey 44 You will eed to proceed to a basic survey whe the iitial appraisal suggests: there is a exposure risk but the extet of the risk is ucertai; major chages have bee made to the process, procedures or cotrol measures sice the last assessmet; uusual or periodic operatios are plaed; a ew process is beig commissioed; or Moitorig strategies for toxic substaces Page 11 of 23

12 Health ad Safety a ew WEL or i-house stadard has bee set. 45 The basic survey estimates your employees persoal exposure ad provides a idicatio of the efficiecy of process ad egieerig cotrols. 46 I the case of a basic survey it is best to look at worst-case situatios, such as the dirtiest, or situatios your employees make the most complaits about. 47 Before moitorig you eed to idetify those employees likely to be at sigificat risk of exposure alog with the coditios givig rise to them. Appedix 1 sets out the factors that ifluece airbore cocetratios ad Appedix 2 outlies the variables which ifluece the desig of moitorig strategies. This iformatio will help you decide what eeds to be doe. 48 You ca use semi-quatitative methods to estimate persoal exposure. These give you a rough umerical estimate of exposure. Some semi-quatitative methods are comparatively iexpesive ad easy to use. 49 Semi-quatitative methods rage from simple techiques, such as chemical idicator tubes (where the absorbet graules i the tube chage colour whe a kow amout of air, cotaiig a chemical, is draw through) to more complex methods which require specialist kowledge, icludig: computer exposure modellig; ad orgaic vapour aalysers such as photoioisatio detectors, portable gas chromatographs ad ifra-red aalysers. 50 Alteratively, validated laboratory-based samplig ad aalytical techiques ca be used (see Appedix 2). If you are usure how to use such techiques, you could cosult a health ad safety professioal such as a occupatioal hygieist. 51 Air velocity meters ca be used to assess local exhaust vetilatio systems to esure that they are performig i accordace with the desig specificatio. Also, the qualitative methods used i the iitial appraisal ca be used here. 52 The basic survey may highlight defects ad deficiecies i cotrol strategies. Based o this ad iformatio gathered durig the iitial appraisal you may coclude that the cotrol of ihalatio exposure is acceptable. If the coclusio is ot certai, you have two choices: carry out a detailed survey ad take remedial actio as ecessary; or take direct actio to cotrol exposure. Detailed survey 53 You ca use this approach whe: the extet ad patter of exposure caot be cofidetly assessed by a basic survey; exposure is highly variable betwee employees doig similar tasks; carciogeic substaces (risk phrase R45 ad R49), respiratory sesitisers (risk phrase R42 ad R42/43) or mutages (risk phrase R46) are ivolved; the iitial appraisal ad basic survey suggest that: - the time-weighted persoal exposure may be very close to the WEL, limits from aother body or i-house stadard; ad - the cost of additioal cotrol measures caot be justified without evidece of the extet of exposure variability; ad Moitorig strategies for toxic substaces Page 12 of 23

13 Health ad Safety udertakig major maiteace ad oe-off jobs such as plat decommissioig. 54 A detailed survey is likely to ivolve techiques already metioed for the iitial appraisal ad basic survey. This will be i cojuctio with more detailed moitorig of your employees potetial exposure to substaces hazardous to health. 55 A detailed survey is most suited to complex processes ad will require a i-depth ivestigatio of the process ad its eviromet, for example: procedures ivolved i the process; work practices; maiteace procedures icludig the type ad frequecy; cotrol measures i use ad their suitability; protective equipmet provided to your employees ad its suitability; previous moitorig results; results of health surveillace programmes; iformatio ad istructio provided to your employees for carryig out the tasks ivolved; ad the extet of the traiig provided to your employees. 56 A detailed survey usually requires more specialist kowledge tha a iitial appraisal or basic survey. It is beyod the scope of this guidace to describe such a procedure i full, especially as detailed surveys vary with the situatio i each workplace. 57 For further iformatio, see Refereces. Additioal iformatio ca also be foud i other HSE publicatios or publicatios from your trade associatio. I additio, you could cosult a health ad safety professioal. The British Istitute of Occupatioal Hygieists holds a Directory of Cosultacies. 58 For certai substaces a detailed survey may eed to iclude the use of biological moitorig. You ca fid out more about biological moitorig ad how you go about it i Biological moitorig i the workplace: A guide to its practical applicatio to chemical exposure. 4 Reappraisal 59 Moitorig for the basic ad detailed surveys may highlight deficiecies i cotrol measures ad poor work practices. 60 Oce you have carried out remedial actio you will eed to see if the chages have had a positive effect. You ca usually do this by a brief reappraisal of the situatio. 61 If the risks to health are judged to be high, additioal exposure moitorig may be advisable. For example, whe: carcioges are used; or there is a very variable patter of exposure. Routie moitorig 62 Whe you decide that the risk to your employees has bee adequately cotrolled, you may decide that you eed to set up a routie moitorig Moitorig strategies for toxic substaces Page 13 of 23

14 Health ad Safety programme to esure that the cotrol measures stay effective. 63 I particular, Schedule 5 of the COSHH Regulatios requires cotiuous moitorig for viyl chloride moomer ad every 14 days for sprays give off from vessels durig electroplatig processes ivolvig hexavalet chromium. 64 Routie moitorig ca be time-cosumig ad expesive over the log term. Cosequetly, if you thik that you may ot be complyig with a WEL it ca be more cost-effective for you to ivest i better cotrol measures. This reduces the: eed for expesive routie moitorig; ad health risks for your workforce. 65 Remember, there are some simple ad iexpesive istrumets available which ca provide iformatio o the cotiued performace of your cotrol methods, for example: pressure sesig devices fitted to vetilatio systems; smoke tubes; or dust lamps. 66 For the results of a routie moitorig programme to be effective i protectig the health of your employees you eed to be able to compare them with those obtaied from previous moitorig exercises. This requires that the programme is well plaed. You eed to cosider: the similarity of the processes ad tasks moitored; where ad at what stage of the process the moitorig was carried out; ad the method of collectig ad aalysig the samples. 67 If a programme is ot well plaed it ca produce a large volume of results ad paperwork without beig of ay actual use i makig sure that your employees health is beig protected. 68 The frequecy of routie surveys will vary. The earer the measured exposure is to the WEL the more frequetly you will eed to moitor. 69 Oe scheme for determiig the frequecy of routie moitorig is give i BS EN 689 Workplace atmospheres: guidace for the assessmet of exposure by ihalatio to chemical agets for compariso with limit values ad measuremet strategy. 11 Iterpretatio of results 70 WELs are set dow as eight-hour time-weighted averages (TWAs) ad/or 15-miute TWAs. This meas that you eed to esure that each result has bee coverted to the specified TWA referece period. 71 The approved methodology for calculatig TWAs is give i EH40. 7 Whe you are covertig the results to TWAs, you eed to give careful cosideratio to the accuracy ad precisio of the samplig ad aalytical methods. You ca do this by cosultig the maufacturer of the equipmet or by seekig specialist advice, for example from the laboratory that carried out the aalysis. 72 Whe comparig the results with WELs, limits from other bodies or i-house stadards, you will eed to take accout of other relevat workplace iformatio you have collected (see Appedix 3). Moitorig strategies for toxic substaces Page 14 of 23

15 Health ad Safety 73 If you have used relatively usophisticated techiques, such as chemical idicator tubes durig a iitial appraisal, do ot place too much cofidece i the level of compliace whe a employee s exposure is withi plus or mius 50% of the WEL. 74 I these circumstaces you should coclude that the level of exposure is ucertai ad a more detailed ivestigatio is required. 75 Whe the exposure is outside this rage you ca be cofidet that o further actio is ecessary. As the strategies ad techiques that you use become more refied, you ca place greater cofidece i the results. 76 I most situatios you will ot eed to carry out a statistical treatmet of the results. However, you may decide to apply a simple aalysis such as a group average ad rage. 77 If you have take a large umber of samples, for example durig represetative (see Appedix 2) ad routie moitorig, a more detailed statistical aalysis may be carried out. This will require a kowledge of statistics. 78 Usig statistics to aalyse the results will give you a better idicatio of the variability i exposure ad extet of compliace with WELs. Further iformatio o statistics is give i Refereces at the ed of this guidace. 79 From the exposure moitorig results you may coclude that: the data are/are ot adequate ad/or represetative of all those exposed; compliace with WELs, limits from other bodies or i-house stadards has/has ot bee achieved; further actios are/are ot ecessary to prevet or reduce exposure; or more moitorig is/is ot eeded. Compliace testig 80 Compliace testig meas comparig your moitorig results with WELs, limits from other bodies or i-house stadards to esure that your cotrol strategy will eable you to comply with COSHH regulatio Whe iterpretig the results ad reachig your coclusio you eed to remember that the COSHH Regulatios require that protectio is give to all employees. If you have carried out group-based, similarly exposed group (SEG) moitorig you eed to show that the coclusio draw for oe employee is equally applicable to others i the same exposed group (see Appedix 2, Paragraph 5). 82 A umber of schemes have bee proposed for compliace testig. BS EN describes some of these schemes. 83 Reducig exposure so far as reasoably practicable meas that: you must reduce exposure to the poit where there is a big differece betwee, o the oe had, the sacrifice (i moey, time or trouble) that would be ivolved i further measures ad, o the other had, the risks from exposure (which should be isigificat). 84 If you are comparig your results with limits from other bodies or i-house stadards you eed to cosider the basis behid the umber i order to decide whether there is a risk to the health of your employees. Moitorig strategies for toxic substaces Page 15 of 23

16 Health ad Safety Appedix 1: Factors ifluecig airbore cotamiat cocetratios 1 It is importat to uderstad the variability of the workplace eviromet before desigig a moitorig strategy. Factors which ifluece the release ad airbore cocetratio of substaces iclude: physical ad chemical properties of the substace such as the vapour pressure, boilig poit ad particle size; the umber of sources from which the substace is released; rate, duratio ad speed of release from each source; arragemet of the process, temperature ad desig of the cotrol measures; variatios i the process, job ad tasks beig carried out. These ca be by the hour, day or eve week; dispersio or mixig of the substace i the workplace air due to geeral or local vetilatio; ad ambiet coditios (temperature, pressure ad humidity). 2 These factors may produce rapid fluctuatios i the cocetratios of the substace over very small distaces. Figure 3 shows a workplace where plat ad process coditios, ad local ad geeral vetilatio characteristics may vary from day to day or display a seasoal patter. Figure 3: Factors ifluecig airbore cotamiat cocetratios 3 As well as the factors outlied i paragraph 1, your employees ca also ifluece the level ad patter of exposure, for example: the type ad positio of each source relative to the employee; the legth of time the employee speds i the viciity of the source; whether the employee has: - direct cotrol over the task or process; ad - a poor appreciatio of the risks ivolved leadig to poor work practices. Moitorig strategies for toxic substaces Page 16 of 23

17 Health ad Safety Appedix 2: Variables ifluecig the desig of moitorig strategies 1 This appedix outlies a umber of variables which you will eed to cosider whe desigig a moitorig strategy. Further iformatio ca be foud i Refereces. Health effect 2 The type of health effect that could be iduced by the substace will ifluece the moitorig procedure. For a substace with acute effects such as eye irritatio, the moitorig techiques eed to be sesitive eough so that peak ad shortterm (15-miute TWA) measuremets ca be take. 3 I the case of chroic effects the moitorig strategy will maily focus o logterm (eight-hour TWA) exposures. This is because, i geeral, the developmet of health effects depeds o exposure over a prologed period of time. 4 You may eed to cosider substaces which have the potetial to iduce both acute ad chroic effects. The moitorig strategy will eed to take this ito accout. Groupig of idividuals 5 The COSHH Regulatios require that you protect the health of all your employees. While you may wish to have iformatio o the exposure patter of all your employees, i may workplaces the umbers ivolved may make the moitorig exercise prohibitively expesive. So moitorig strategies usually focus o groups of employees who do similar jobs i similar ways. These groups are described as similarly exposed groups (SEGs). The groupig of potetially exposed employees ca be made by careful observatio of such commo factors as: similarity of the tasks performed (ot ecessarily the same job); exposure to the same rage of airbore cotamiats; ad similarity of eviromet (process, exposure source ad cotrol measures). 6 If you have carried out group samplig, the results eed to be carefully aalysed to make certai that they are equally valid for all employees i the SEG. A wide differece i the results from differet idividuals idicates cosiderable variatio withi the SEG. 7 I these circumstaces you eed to further sub-divide the group or reassig employees to a more appropriate SEG. Repeated measuremets from the same employee ca help you decide whether that employee eeds to be reassiged or a SEG further sub-divided. 8 As a useful guide: whe a idividual s exposure is less tha half or greater tha twice the group average, the the idividual eeds to be reassiged to a more appropriate SEG. Moitorig strategies for toxic substaces Page 17 of 23

18 Health ad Safety 9 You ca the focus your risk cotrol strategies ad further moitorig o those employees most at risk from excessive exposure. Types of exposure measuremet 10 As idicated i paragraphs 22 to 27 i the mai text, there are two mai types of moitorig, persoal ad fixed place (static). The purpose of persoal moitorig is to establish the cocetratio of the airbore substace withi the breathig zoe of the employee. 11 The breathig zoe is the space withi cm of the perso s ose ad mouth. This covetio permits the placig of persoal samplers o the employee s lapel. However, airflows ad activities are variable. This meas that the positioig of the sampler (right lapel, left lapel or helmet) may cause a over or uder estimate of the average cocetratio ihaled by the employee. For example, the fume geerated durig solderig operatios will rise straight upwards because of thermal currets. This may miss a sampler placed o the employee s lapel. 12 Therefore, you eed to give careful cosideratio to the process, task ad work practices before placig the sampler ad durig the moitorig exercise so that the results ca be correctly iterpreted. 13 There are two distict types of persoal measuremet; represetative ad worst-case: represetative measuremets take ito accout all possible workplace iflueces icludig the variables described i Appedices 1 ad 2. worst-case measuremets ca be take where you ca clearly idetify employees who are subject to periods of high exposure. The moitorig period ca the be selected to cover these evets. For the purposes of determiig the eight-hour TWA exposure, you ca cosider the exposures foud i these circumstaces as applyig to the whole of the workig period. This presumptio will err o the side of safety oce acted o. Number of samples 14 Takig oe or a few samples o oe day will ot provide you with sufficiet iformatio o which to base coclusios about log-term exposures. I reality the umber of samples that you ca take is usually costraied by the resources available to you. You eed to use your judgemet whe decidig o sample size, especially whe small groups are cocered. 15 For worst-case moitorig, as a rule of thumb, at least oe employee i five eeds to be moitored from a properly selected SEG, uless a smaller umber ca be justified. 16 For represetative measuremets: if there are less tha te employees i the SEG oly five eed to be icluded i the moitorig exercise; for complex situatios ivolvig more tha te employees i the SEG, see Refereces. Moitorig strategies for toxic substaces Page 18 of 23

19 Health ad Safety Moitorig period ad duratio 17 If the process is cotiuous ad has miimal variatio, the choice of moitorig period is ot of great importace. However, if the process is cyclic it is critical that you carry out the moitorig at the time your employees are beig exposed. 18 The choice of the moitorig period is also closely liked to the type of health effect associated with the substace (see Appedix 2, paragraph 2). The duratio of the moitorig has to be sufficiet to: give results which are represetative of the whole rage of exposures, icludig peak exposures; ad allow the relevat TWA exposure to be calculated. 19 You also eed to esure that start-up procedures at the begiig of shifts ad ed-of-shift tasks such as clea dow operatios are icluded. 20 I the case of cotiuous, well-cotrolled processes with miimal variability you ca use a moitorig duratio of less tha the full shift (or eight-hour referece period). I such circumstaces the moitorig period may cover at least 25% of the workig shift ad iclude periods of high exposure. 21 If there is cosiderable variatio i the work patter you may eed to moitor o a umber of days to cover all aticipated variatios. 22 Remember, usampled time represets a serious weakess i the credibility of ay exposure measuremet. Cosequetly, durig this time, you eed to make careful observatio of work practices, etc. Samplig ad aalysis equipmet 23 The moitorig equipmet ad method of aalysis that you choose has to fit the requiremets of the strategy ad ot vice versa. However, the practicalities of the workplace may require you to make a compromise. 24 The samplig techique you choose eeds to be appropriate for the give work situatio ad ot sigificatly ifluece the employee s behaviour by beig: too heavy; obstructive; or oisy. 25 The equipmet eeds to: be robust eough to cope with the demads of the work eviromet; have sufficiet battery life; ad be certified for use i flammable atmospheres, if ecessary. 26 The errors i the samplig ad aalysis equipmet eed to be determied ad supported whe appropriate by quality cotrol protocols. 27 Examples of atioal quality schemes iclude the: Natioal Measuremet Accreditatio Scheme (NAMAS); Workplace Aalysis Scheme for Proficiecy (WASP). 28 Specific iformatio o samplig ad aalytical techiques for may Moitorig strategies for toxic substaces Page 19 of 23

20 Health ad Safety substaces ad processes ca be foud i HSE s Methods for the determiatio of hazardous substaces (MDHS) series. You ca also get iformatio from equipmet maufacturers ad aalytical laboratories. Appedix 3: Core iformatio 1 A set of moitorig results i isolatio is rarely sufficiet to permit coclusios to be made with cofidece o the level of exposure ad the ecessary cotrol measures. Other essetial iformatio is ofte referred to as core iformatio. 12 Collectig core iformatio at the time you carry out the moitorig will allow you to make reliable decisios about: the level of exposure; ad the eed or adequacy of cotrols. 2 Table 1 lists the iformatio which you may eed to collect whe carryig out exposure moitorig. Table 1: Core iformatio Key categories Premises Workplace Worker activity Product Chemical aget Exposure modifiers Measuremet strategy Measurig procedure Result Refereces Data elemet This sectio icludes details o the ame of your premises, address ad what type of work you do. This sectio gives iformatio o the departmet, work area ad process. Details of the employee, eg ame, ID umber, male/female, professio, job title ad tasks carried out are icluded i this sectio. This is the ame of the product your employees are usig. This is the substace which you are moitorig for. Chemical idetificatio umbers ca be oted if you kow them (CAS or EINECS umber). The curret WEL or other stadard ca be oted. These are importat factors which will help you iterpret the moitorig results. You ca ote the thigs which affect your employees exposure, for example: is exposure cotiuous throughout the day or does it occur i occasioal periods; what type of cotrols do you use: - local/geeral vetilatio; - maximisig the distace of the employee from the process; - miimise the time spet at the process; - the use of respirators; is the area where the employee works: - idoors or outdoors; - a ope or eclosed space. Note the strategy that you used i the survey i this sectio, eg was it a worst-case or represetative situatio. Describe the procedure you used to carry out the moitorig, procedure, eg type of sample, duratio of exposure ad moitorig. Detail the sample result, the TWA result ad uits. Note the report referece umber ad the ame of the perso who carried out the survey ad date. Moitorig strategies for toxic substaces Page 20 of 23

21 Health ad Safety Refereces 1 Cotrol of Substaces Hazardous to Health Regulatios 2002 SI 2002/2677 The Statioery Office 2002 ISBN (as ameded) 2 Approved supply list. Iformatio approved for the classificatio ad labellig of substaces ad preparatios dagerous for supply. Chemicals (Hazard Iformatio ad Packagig for Supply) Regulatios Approved list L129 (Seveth editio) HSE Books 2002 ISBN Chemicals (Hazard Iformatio ad Packagig for Supply) Regulatios 2002 SI 2002/1689 The Statioery Office 2002 ISBN Biological moitorig i the workplace: A guide to its practical applicatio to chemical exposure HSG167 HSE Books 1997 ISBN Maagemet of health ad safety at work. Maagemet of Health ad Safety at Work Regulatios Approved Code of Practice ad guidace L21 (Secod editio) HSE Books 2000 ISBN Cotrol of substaces hazardous to health (Fifth editio). The Cotrol of Substaces Hazardous to Health Regulatios 2002 (as ameded). Approved Code of Practice ad guidace L5 (Fifth editio) HSE Books 2005 ISBN EH40/2005 Workplace exposure limits: Cotaiig the list of workplace exposure limits for use with the Cotrol of Substaces Hazardous to Health Regulatios 2002 (as ameded) Evirometal Hygiee Guidace Note EH40 HSE Books 2005 ISBN Guide to occupatioal exposure values 2005 America Coferece of Govermetal Idustrial Hygieists 2005 ISBN BS EN 482: 1994 Workplace atmospheres - geeral requiremets for the performace of procedures for the measuremet of chemical agets British Stadards Istitutio 10 The dust lamp: A simple tool for observig the presece of airbore particles MDHS82 HSE Books 1997 ISBN (available free olie at: BS EN 689: 1996 Workplace atmospheres - guidace for the assessmet of exposure by ihalatio to chemical agets for compariso with limit values ad measuremet strategy British Stadards Istitutio 12 Occupatioal exposure databases: a proposal for core iformatio for workplace exposure measuremets o chemical agets Europea Foudatio for the Improvemet of Livig ad Workig Coditios 1996 ISBN Further readig Samplig strategies for airbore cotamiats i the workplace British Occupatioal Hygiee Society (BOHS) Techical Guide No 11 H ad H Scietific Cosultats 1993 ISBN Harrigto JM ad Gardier K Occupatioal hygiee Blackwell Sciece 1995 ISBN Moitorig strategies for toxic substaces Page 21 of 23

22 Health ad Safety Hawkis N, Norwood S et al A strategy for occupatioal exposure assessmet America Idustrial Hygiee Associatio 1991 ISBN Roach S A most ratioal basis for air samplig programmes A. Occ. Hyg Dewell P Some applicatios of statistics i occupatioal hygiee British Occupatioal Hygiee Society (BOHS) Techical Hadbook No 1 H ad H Scietific Cosultats 1989 ISBN Whylie D Settig exposure limits: what to do whe there s o stadard Occupatioal Health ad Safety Caada (6) Useful address British Istitute of Occupatioal Hygieists/British Occupatioal Hygiee Society 5/6 Melboure Busiess Court Milleium Way Pride Park Derby DE24 8LZ Tel: Fax: [email protected] Website: Moitorig strategies for toxic substaces Page 22 of 23

23 Health ad Safety Further iformatio For iformatio about health ad safety rig HSE s Ifolie Tel: Fax: Textphoe: [email protected] or write to HSE Iformatio Services, Caerphilly Busiess Park, Caerphilly CF83 3GG. HSE priced ad free publicatios ca be viewed olie or ordered from or cotact HSE Books, PO Box 1999, Sudbury, Suffolk CO10 2WA Tel: Fax: HSE priced publicatios are also available from bookshops. British Stadards ca be obtaied i PDF or hard copy formats from the BSI olie shop: or by cotactig BSI Customer Services for hard copies oly Tel: [email protected]. The Statioery Office publicatios are available from The Statioery Office, PO Box 29, Norwich NR3 1GN Tel: Fax: [email protected] Website: (They are also available from bookshops.) Statutory Istrumets ca be viewed free of charge at Published by HSE 01/10 Page 23 of 23