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ABDOOO19376 t ]|ec/m Authors Jack SMIT (Solvay Weesp) Willy ASNONG (Solvay Bruxelles, DCRT-HSE) Version 1 07 01 2002 INDUSTRIAL HYGIENE GUIDELINE: The assessment of Exposure to Polyvinyl Chloride Dust Distribution (ex) ABDOOO19377 ICVm Authors Jack SMIT (Solvay) Willy ASNONG (Solvay Bruxel, DCRT-HSE) Version 1 07 01 2002 INDUSTRIAL HYGIENE GUIDELINE: The assessment of Exposure to Polyvinyl Chloride Dust SUMMARY This document describes the assessment of the exposure to airborne Polyvinyl Chloride dust in relation with the applicable occupational exposure limits The guidance note is based on several documents from the European Centre of Normalisation (CEN), the Health and Safety Executive (HSE-UK) and the National Institute of Occupational Safety and Health-US (NIOSH) and has been reviewed by IndusTox Consult (Nijmegen Netherlands) who delivers services in the domain of exposure assessment of chemicals in the work environment ABDOOO19378 1 Version 1 07 01 2002 INDUSTRIAL HYGIENE GUIDELINE: The assessment of Exposure to Polyvinyl Chloride Dust CONTENTS 1. INTRODUCTION........................................................................................................................ 3 2. GENERAL PRACTICE................................ -.............................. -......................................... 3 3. OBJECTIVES OF THE EXPOSURE ASSESSMENT................................ -.................... .4 4. BASIC CHARACTERIZATION................................-.............................. -.........................5 5. ESTABLISHING SIMILAR EXPOSURE GROUPS <SEG).............................................. 7 6. AIR MONITORING..................................................................................................................... 8.. 6 1 INTRODUCTION ... 6 2 AIR SAMPLING METHODS 6 3 DIRECT READING MONITORS 6 4 ANALYTICAL METHODS -- 64 1 Gravimetric method .- 6 4 2 Storage and transport of the filters 6 4 3 Determination of PVC-DUST by total Chloride analysis 6 4 4 Quality control 6 5 MONITORING OBJECTIVES 6 5 1 Initial Monitoring .. 6 5 2 Periodic Monitoring 6 5 3 Diagnostic Monitoring 6 6 MONITORING METHODS - 6 6 1 Personal air monitoring ... 6 6 2 Attaching the sampling equipment on the worker 6 6 3 Area monitoring 6 7 AIR SAMPLING PLAN 6 7 1 General 672 Initial monitoring . 6 7 3 Periodic measurements _8 8 11 12 12 13 13 14 14 .14 15 15 - 15 15 15 li L6 16 17 17 ABDOOO19379 2 Version 1 07 01 2002 7. CONCLUSION OF THE ASSESSMENT OF OCCUPATIONAL EXPOSURE.......... 19 7 1 INITIAL MONITORING ._ 7 2 PERIODIC MONITORING 7 2 1 Judge if the exposure profile has a log-normal distribution 72 2 Calculate the probability of exceeding OEL 7 2 3 How to cope with nondetectable values in a statistical evaluation9 19 . 19 . 19 19 ..20 8. RECORDKEEPING AND REPORTING...............................................................................21 9. LITERATURE................................-.............................. -.............................. -.........................22 Annex 1 Annex 2 Annex 3 Annex 4 Annex 5 Annex 6 Inhalable dust samplers Respirable dust samplers Analytical methods for chlorides Flowsheet "Judging the exposure profile" Glossary Statistical Tool ABDOOO19380 Version 1 07 01 2002 1. INTRODUCTION An exposure assessment program shall be established to evaluate the potential for employee exposure to airborne Polyvinyl Chloride dust m relation with the applicable occupational exposure limits and to determine if established control measures are functioning properly or if additional control measures are needed This document describes the assessment of the exposure to Polyvinyl Chloride dust and is based on several documents from the European Commission of Normalisation (CEN), HSE and National Institute of Occupational Safety and Health- US (NIOSH) and has been reviewed by IndusTox Consult (Nijmegen Netherlands) who delivers services in the domain of exposure assessment of chemicals m the work environment. 2. GENERAL PRACTICE The common industrial hygiene practice is the following 2 1 Exposure to Polyvinyl Chloride (PVC) dust like all chemicals should be kept as low as reasonably practicable 2 2 In any case, exposure should not exceed the naional legal occupational exposure limit 2 3 Before every assessment, the validity of the exposure limits must be checked Hereby a list of the applicable exposure limits for PVC dust Country Limit Inhalable Respirable TWA1 PVC-dust PVC-dust 8 hour mg/m3 mg/m3 Adoption Date PVC-dust Germany Netherlands UK Sweden MAK MAC OEL OEL 2,52 10 1 1,5 5 05 proposal 1996 1996 as Particulates Not Otherwise Classified (PNOC) Germany MAK 4 1,5 proposal US\ACG1H3 TLV 10 3 1989\95 US\OSHA PEL 15 5 1) Time-Weighted Average 2) to be reviewed in 2002 ABDOOO19381 4 Versionl 07 012002 Which limit to comply with9 The OELs for PVC dust in the different countries are based on either the inhalable dust fraction and/or the respirable dust fraction In order to be able to merge the measurement data of all ECVM members for future epidemiological studies, it is recommended to conduct simultaneous measurements with both inhalable and respirable dust samplers m sufficient number of different exposure situations Unusual Work Schedules Normally the OELs are time weighted averaged for the convential 8 hour day and the 40 hour week In case the working shift is longer the OEL should normally be adjusted But for PVC dust no correction factor is necessary (by Law of Habei^) 2.4 Adequate control of exposure Where exposure to PVC-dust cannot be avoided, control should be achieved by material, plant and process controls or other suitable control techniques Only Wiere the measures taken do not prevent adequate control of exposure, suitable respiratory and other personal protective equipment should be worn OBJECTIVES OF THE EXPOSURE ASSESSMENT Before the process starts, the exposure assessment goals must be clearto everyone involved in the assessment A strategy directed at assessing all exposure for all workers on all days is highly recommended In addition to ensuring compliance with existing occupational limits (OELs), this strategy provides an understanding of the day-to-day distribution of exposures Exposure assessment findings can then be used to address present-day health risks and to construct exposure histories If a historical database is maintained, the exposure assessment data may be used to address future health issues for individual workers or groups of workers In the latter case, the data may be used to support epidemiological studies ABDOOO19382 5 Version 1 07 012002 The goals of a comprehensive exposure assessment include 1 Characterisation of potential exposures to all PVC dust, 2 Characterisation of exposure intensity and temporal (hour-to-hour/day-to-day) variability faced by all workers, 3 Assessment of the potential risks (e g risk of potential harm to employee health, risk of non-comphance with governmental regulations, etc ), 4 Prioritisation and control of exposures presenting unacceptable risks, 5 Identification of exposures for which additional information is needed (e g Initial monitoring, etc ), 6 Documentation of exposures and control of efforts, and communication of exposure assessment findings to all affected workers and to those who are involved in worker health protection (e g management, occupational physician, engineering staff, etc ), 7 Maintenance of a historical record of exposures for all workers so that futire health issues can be addressed and managed relative to actual exposure information, 8 Accomplishment of the preceding steps with efficient and effective allocation of time and resources 4. BASIC CHARACTERIZATION Common description The collection and organisation of available information on the workplace, workforce, agents, historical exposure data, etc to assess and evaluate health risks As a minimum, the following questions must be answered: What processes and operations, and what tasks and work prxtices, pose significant potential for worker exposures to PVC dust89 How is the work organised9 What are the significant sources of exposure9 What controls are in place, and how are they used9 ABDOOO19383 6 Version 1 07 01 2002 Workplace information Work involving PVC~dust should be assessed in order to identify sources of dust or the provision of new controls The work should be re-assessed whenever changes are introduced which significantly affect the material, plant or process controls In practice exposure to PVC-dust in manufacturing or in user industries is most likely to arise during the following operations Drying and screening, including cyclones Handling, transfer and dispatching operations Bagging and weighing Bag opening and powder transfer Batch weighing Mixing and blending Finishing of PVC articles (sanding, gnnding, cutting) Grinding PVC-recycled products Preparing a written description and/or a schematic diagram of the process or operation can sources ofpotential exposure, location of chemicals and tasks, ventilationand other control methods Workforce information The goal of the work force characterisation is to understand the division of labor and the work practices Detailed knowledge of routine and non-routine work assignments, work schedules and tasks must be acquired It helps to subdivide the workers in similar exposure groups, by descnbing jobs, tasks, and number of workers and frequency The workforce characterisation should be based on a variety of resources, including the plant's organigram, job descriptions, worker interviews, management interviews and most important, careful observation of work practices and the workplace If in grouping workers, the industrial hygienist deviates from the personnel system, accurate records will be needed relating the similar exposure groups to the personnel record keeping system Incongruence between industrial hygiene and personnel job classification schemes could make investigation of future issues difficult More and more, many workplaces rely on contract labor to perform routine and nonroutine work It is important for contractors to be included in the exposure assessment process The mechanism and requirements for assessing the exposure of contract labor should be established in the contract Larger or more sophisticated contractors may have their own exposure assessment capabilities For other contractors, it might be more effective to rely on the skill and expertise of the client Example Operator PVC Spends about 40% oftime m the PVC production areas checking equipment, adjustingflows, andpreparing equipmentfor maintenance, about 10% of time is spent collectingprocess samples and an other 25% is spent in lab running analyses on all process samples, remaining time is spent in control room areas ABDOOO19384 7 Version! 07 01 2002 5. ESTABLISHING SIMILAR EXPOSURE GROUPS (SEG) In most workplaces, it is difficult to measure personal exposures to all agents for every worker Although there are examples of the daily use of dosimeters (e g measuring ionising radiation exposure), it is not practical and seldom possible A strategy for meeting these challenges is to assemble workers believed to have similar exposures into a group Similar exposure groups (SEGs) are groups of workers having the same general exposure profile because of the similarity and frequency of the tasks they perform, the materials and processes with which they work, and the similarity of the way they perform the tasks The qualitative or quantitative characterisation of the exposure of one or a few workers m the group is then considered `'representative" of the exposures of every worker in the group There are several strategies to establish the SEGs Classifying by process, and agent,Classifying by process, job, and agent, Classifying by process, job, task, and agent, Classifying by process, task, and agent, Classifying work teams, Classifying non-repetitive work Similar exposures groups are established by observation using data gathered during characterisation of the workplace, work force, and agents SEGs established by observation are generally described by the following determinants `'process, job, task and agent" This classification is the most often used, and also the method that is introduced m this document Classifying by Process, Task-Based and Agent Approach: Each job description is an entry represented by at least one worker on at least one day Common examples are Area/Task Total Shift Freq of % task\shift operator, Acid Control Room Laboratory Sampling Adjust flows Equip Check Operator, mixing Weighting Dumping others 25 25 10 10 30 25 25 10 1 2 2 2 3 2 2 Task Duration (min) 120 60 24 24 48 120 60 24 Degree of Exposure for each agent HC1 Cla PVC Noise ABDOOO19385 8 Version 1 07 012002 6. AIR MONITORING 6.1. INTRODUCTION A competent person in industrial hygiene shall define the air monitoring prog*am The goal of this program is to establish the sampling plan (e g sampling frequency, location, and sampling duration), selection of the air monitoring equipment, data evaluation and analysis ofthe samples and to verify 1 whether the 8-hour time-weighted average concentrations of Polyvinyl Chloride dust m the breathing zone exceed the specified limits 2 if established control measures are functioning properly or if additional control measures are needed 6.2. AIR SAMPLING METHODS Inhalable versus respirable dust There is a broad international agreement (ISO, ACGIH and CEN) on the qualitative and quantitative definitions ofthe exposure assessment criteria for aerosols that reflect as closely as possible the nature of the human exposure Three main components are as follows Inhalable fraction representing the aerosol fraction that enters the nose and/or mouth during breathing and the Thoracic fraction representmg the subfraction of inhalable aerosols that penetrates into the respiratory tract below the larynx and the Respirable fraction representing the subfraction of the inhalable aerosol that penetrates to the alveolar region of the lung Only for the inhalable and respirable fractions OEL's are established For PVC in most of the countries the inhalable and respirable fractions should be measured ABDOOO19386 9 Version I 07 01 2002 Principle A measured volume of air is drawn by a pump through a membrane filter in a sampler Samplers for inhalable dust and samplers for respirable dust (including a pre-selector) are described in Annex 1 and Annex 2 Pumps Battery-operated sample pumps can be used for personal and area sampling These pumps are manufactured by a variety of vendors such as Gillian, SKC, MSA and Casella These pumps have to be capable to run for 8 hours or the duration of the total shift Each pump should be calibrated with an air flow meter or other primary source (e g bubbletube, filmmeter) before and after sampling (with a filter in the sampler head) The volume of air calculated by calibration after the sampling, should be within 5% of the volume of air calculated by calibration before the sampling Sampling Inhalable PVC-dust. A sampler for inhalable dust should comply with the standardised conventions for healthrelated sampling of aerosols in workplaces ( EN481, ISO 7708) The European Committee of Normalisation (CEN)1) has investigated eight personal inhalable dust samplers which are in use in various European countries and US (only closed face sampler) The results of this laboratory study ldoitified correction factors for each sampler, to obtain satisfactory performance In another stud>^) a new RespiCon 3-stage sampler was tested with 5 other samplers With the RespiCon the respirable, thoracic and inhalable fractions can be measured For the inhalable fraction the sum of the 3 filters must be calculated The new Button sampler is not yet tested, in the stud>^only a prototype was tested with a different sample flow But following the manufacturer, this sampler performs closely the ACGIH/ISO/NEN criteria The correction factors depend on the wind speed at the workplace The 10 samplers are referred to m Annex I Sampling when the wind speed exceeds 1 m/s (197 feet/minute) is not recommended However, comparative field studies4 in the Netherlands show that in practice the difference between two different dust samplers can be 60% or higher ABDOOO19387 10 Version 1 07 01 2002 RECOMMENDED APPROACH FOR SAMPLING INHALABLE PVC DUST Every country has his own preference for a specific dust sampler, but for standardisation reasons it is recommended that everyone will use the same dust sampler If all measurements are performed with the same method, the results of all ECVM-members will be easier to compare Each sampler has its advantages and disadvantages, but it is recommencbd that all sampling would be done by using the IOM-sampler This IOM-sampler has been developed specifically, to sample the mhalable dust fraction and is the only one that is commercially available in all countries If measurements were already done m a appropriate way with one of the other samplers, it is recommended that in one or two exposure situations the measurements would be repeated m sampling simultaneously with the IOM-sampler and the sampler used in the previous measurement campaignWith this comparison also the other measurements can be corrected Example an exposure situation is sampled simultaneously with the IOM-sampler and the sampler that was used in the past, and the IOM sampler gives a mean concentration of 4 0 mg m3 and the other sampler gives a mean concentration of 3 2 mg m3 The results of the sampling by the other sampler can be corrected with a factor of 4 0/ 3.2 = 1 25 Sampling Respirable PVC-dust A sampler for respirable dust should comply with the standardised conventions for healthrelated sampling of aerosols in workplaces (EN481, ISO 7708) There are a few samplers available, which comply with this standardisation The samplers are referred to in Annex 2 There is no information available, stating that one specific sampler should be recommended Filter material Ifsampling of PVC-dust is earned out for the measurement of the gravimetric concentration, pre-weighed glass fibre filters (e g Whatman GF/A) may be used Glass fibre is the easiest matenal to use, because there are no problems with static electncity But fibre loss from glass fibre filter may occur during handling and may bias significantly the result if less than 1 mg dust is collected At lower concentrations silver or membrane filters (e g ceiblose nitrate, polycarbonate, Teflon or PVC filters should be used Filters made of PVC, can show excessive static build up, mixed ester or cellulose filters do not have these drawback in the same degree A static eliminator (plasma ion source or radioactive source) can be used to dissipate any electrostatic charge before weighing. ABDOOO19388 11 Version 1 07 012002 Filters made of mixed esters or cellulose can show excessive weight change due to moisture absorption But there is some experience that also glass fibre filters showed excessive weight changes due high relative moisture Ifthe determination of PVC in the collected material is required (see 5 2), a polycarbonate filter should be used Moisture problems The use of a desiccator can solve this problem, equilibrating the filters for at least 2 hr in a desiccator with on the bottom a saturated solution of K03 This method gives a relative moisture of44 % RECOMMENDED APPROACH FOR FILTER MATERIAL For standardisation reasons it is recommended to use the polycarbonate filters If all measurements are done with the same method, the results can be compared easier Additionally, if afterwards it is deemed necessary to analyse the amount PVC on the filter, the polycarbonate filters are the appropriate ones Attaching the sampling equipment on the worker Attach the sampler head to the operator, m preference on the lapel, not more than 30cm away from the nose-mouth region The sampler head is connected to the pump which is attached to a belt around the waist of the worker 6.3. DIRECT READING MONITORS A general feature of real-time dust monitors is the short average time, which makes these monitors suitable for objectives such as detection of peak exposures, emission source detection, and trend analyses of background concentrations ABDOOO19389 12 Version 1 07 01 2002 6.4. ANALYTICAL METHODS 6.4.1. Gravimetric method A balance capable of weighing with a resolution of 10 pg or better is suitable All filters should equilibrate for 30 minutes or more in the weighing room When humidity is variable a desiccator should be used Weigh each filter before the sampling activities, including a minimum of three field blanks before sampling Repeated weighing of the filters gives a better performance The field blanks should be exposed to the same climate conditions as the filtersused in the field After the sampling repeat the weighing including the blank filters The mean weight changes of these unexposed blank filters should be used as a correction factor (+ or -) in the calculation below (see bi) Sample quantity The limit of detection (LOD) of material that can be weighed with a balance with a weighing precision of 10 pg, is approximately 300 pg For example at an air concentration of 0 5 mg/m3 it is necessary to collect a volume of0,6 m* air to achieve this For a balance with a weighing precision of 1 pg, the limit of detection (LOD) of material that can be weighed is approximately 50 pg For an air concentration of 0 1 mg/m5 it is necessary to collect a volume of 0,5 m3 air to achieve this The limit of detection (LOD) of the gravimetric analysis can estimated as approximately three times the standard deviation of weight changes of the group of three (more is better) blank filters included in each batch of samples, weighed before and after sampling Calculation For determination of inhalable or respirable PVC-dust in! = initial weight of filter (mg) m2 = weight of filter after sampling (mg) bi = mean weight changes (m2 - mi) of unexposed filters (mg) (+ or -) q = sampling flow rate (1/mm) t = sampling time (min) c = correction factor inhalable dust samplers (Annex 1) The concentration of (PVC) dust ui air 1000 (m2 - m, - b,) x c mg/m3 qt ABDOOO19390 13 Version 1 07 01 2002 6.4.2. Storage and transport of the filters For samplers that collect the dust on a filter alone Remove the filter from each sampler using a flat-tipped forceps, - place in a labelled filter transport container and close with a hd, - take particular care to prevent dust being dislodged from heavily loaded filters For samplers that use an internal cassette (e g the IOM sampler), Remove the cassette from the sampler and fasten with the transport clip supplied by the manufacturer, - label the cassette to ensure proper handling Transport the samples to the laboratory in a container designed to prevent damage during transit and label to ensure proper handling Special precautions to recover lost material, for example the use of cassette covers or filter containers, are likely to be needed where samples are sent by post In this case one should weigh the filter and the cassette together After sampling,the filter is placed again in the cassette and both are weighed together 6.4.3. Determination of PVC-DUST by total Chloride analysis With the gravimetric method, all the sampled dust should be indicated as PVC-dust So, if the measured concentration is exceeding the exposure limit, it may be important to determine the PVC-content in the sample in order to calculate the real concentration of PVC in the work environment Filter material If determination of PVC in the collected material is required, polycaibonate filters should be used Destruction of PVC The determination ofthe PVC content m the sample is based on the thermal destruction of PVC in a furnace with a capacity of >1000 DC which results in the liberation of the chloride ion The chloride is trapped into 10 ml water Also other destruction methods, can be used if it is possible to trap the chloride in water Analysis of chloride The amount of chloride in water is determined very easy spectrophotometrically with the Dr Lange chloride test LK 311 This method has a very low detection limit of 10 Qg chlonde / filter For example, sampling during 15 minutes at a sample flowrate of 2 litres per minute, gives a minimum detection limit of < 0,3 mg chloride !m (i e 10pig/15'*2l) The calculation of the PVC concentration starting from the chloride concentration, must take into account the percentage of chlonde in the PVC-compound handled dunng the monitoring Principle : C1-+ mercurythiocyanate HgCfeD + SCN'1 + FE3+ 0 coloured Fe(SCN)3) Warning : With this method not only the chlonde of the sampled PVC will determined, but also background chlonde from e g NaCl or FeCfc When there is any doubt, background samples should be taken Ask your COHYG for information about background sampling In annex 3, the analytical methods for chlondes is given ABDOOO19391 14 Version 1 07 012002 6.4.4. Quality control Responsible person for monitoring program The person who is responsible for the assessment should have enough experience and education to perform this assessment and monitoring program Analytical Laboratory Before deciding which analytical laboratory is going to perform the weighing of the filters, calibrating the pumps or performing the specific analysis, one should verify if this laboratory is certified to perform this activities Has the laboratory been certified by an external control agency ISO, GLP, etc9 Is the Laboratory Analyst qualified by training9 eg school, on the job, course Is the laboratory participating in Round Robin performance tests9 Are laboratory blanks used to check the accuracy of the analytical method A media (laboratory) blank is an unexposed filter, not taken to the field or shipped, used for background correction of sample readings or for recovery studies9 Do the laboratory reports the coefficient of variation of their analyses9 Sampling In order to check the accuracy of the air sampling and analytical method one should Submit routinely field blank samples to the laboratory together with field samples9 A field blank is a filter, handled exactly the same as the field samples, except that no air is drawn through it Take some samples in duplicate 6.5. MONITORING OBJECTIVES. There are different monitoring objectives or strategies that broadly can be grouped into three categories 6.5.1. Initial Monitoring In case the basic survey (e g EN68915 1 4 2 or the company specific exposure assessment methodology) can not give sufficient information if an exposure profile of a Similar Exposure Group (SEG) is acceptable (< 10% of exposure limit) or unacceptable, (> 100% of exposure limit) the assessment of the exposure profile is uncertain In that case initial monitoring is mostly used to assess the compliance with an exposure limit Only personal monitoring techniques are appropriate ABDOOO19392 15 Version 1 07 01 2002 6.5.2. Periodic Monitoring Periodic monitoring is used to evaluate periodically exposure profiles that are judged as acceptable and which have a mean concentration that is greater or equal to 10% and lesser than 100% of the exposure limit If documented properly, periodic-monitoring data can also be used for future epidemiological studies In the case of periodic compliance monitoring, only personal monitoring techniques are appropriate 6.5.3. Diagnostic Monitoring When trying to identify the exposure source and to understand how source, tasks, and other variables (e g production rates) contribute to worker exposure, diagnostic monitoring should be conducted The results can help the industrial hygienist to define the most appropriate and efficient control strategies for unacceptable exposures If the source is from a fixed piece of equipment, area-monitoring techniques are appropriate If the source moves with the worker or depends on individual work practices, personal monitoring techniques are appropriate In most cases, measurement averaging times should reflect process cycle times rather than the exposure limit averaging times Using a longer averaging time will simply average out the actual data required for problem identification For example when one intends to monitor the exposure during a task of 10 minutes but sampling time start 10 minutes before and continues 10 minutes after the task, you will measure a concentration 10730* of the real concentration during the task 6.6. MONITORING METHODS 6.6.1. Personal air monitoring The best estimate of an individual's exposure is obtained by taking beathing zone samples (personal sampling) for the entire working period This optimum isnot always practical and the actual sampling time should be arranged so that it covers certainly the potentially highest exposures, and at least 75% of the reference period 6.6.2. Attaching the sampling equipment on the worker Attach the dust sampler to the operator, in preference on the lapel, not more than 30cm away from the nose-mouth region The sampler is connected to a pump that is attached to a belt around the waist of the worker 6.6.3. Area monitoring Area (or fixed-point) measurements can be done with the same devices as used for personal air monitoring or with a real-time dust monitor Area momtonng can be used to identify the ABDOOO19393 16 Version 1 07 01 2002 background concentrations at the workplace and are useful to measure the effectiveness of control measures (e g local exhaust ventilation) over a period of time Area-point measurements should not be used to verify compliance with an exposure limit 6.7. AIR SAMPLING PLAN 6.7.1. General To compare an exposure level of a substance with its exposure limit, one needs to know the concentration ofthe substance in the breathing zone extrapolated to the same reference period as that is used for the limit value (i e 8 hours for chlorides) At least 75% of the reference period should be sampled However, if during more than 25% of the reference period no exposure occurs, a sampling time less than 75% is permissible For work shifts greater than 8 hours, one should verify if the exposure limit must be adjusted and the sampling time should be 75% of the longer work shift Pump out or on when respirator is used? In assessing the compliance of a SEG with the exposure limit, one should sample the whole exposure period without taking into account the wearing of a respirator That is what you can interpret and read in European guidelines and OSHA standards "Employee exposure" and other similar language referring to the air agent level to which an employee is exposed means the exposure to the airborne agent that would occur if the employee was not using respiratory protective equipment". If an exposure of a SEG is not in compliance with the exposure limit, immediately the workers must wear respirators and technical measures must be considered to control exposure If the technical measures cannot reduce exposure to an acceptable level, workers should continue to wear respirators In order to verify if the respirators do protect the workers adequately, one can measure the "daily intake" by the workers as follows Sample the most exposed task(s) for which the worker must wear adequate respirators and calculate the daily intake by subtracting this concentration from the result of the compliance measurement result for the same job, but taking into account also the protection factor of the respirator (e g halfface P2 toxic dust mask has a protection factor of 10, that means that the concentration measured for the specific task must be divided by 10) ABDOOO19394 17 Version 1 07 01 2002 Note These "daily intake" measurements are not obligatory to perform Only m some countries these kind of measurements are allowed to prove compliance with national regulations The policy should be to comply with an Occupational Exposure Limit (OEL) at any time Only when this is not (yet) possible, "daily intake" measurements can prove that the measures (personal protection in this case ) are adequate 6.7.2. Initial monitoring If after the basic survey (e g EN689 / 5 1 4 2 or the company specific exposure assessment methodology) an exposure profile of a SEG can not be classified as acceptable or unacceptable, initial compliance monitoring is used to assess adherence to an exposure limit The number of measurements varies form 3 to 6 samples Number of measurements In the first step of this subsequent exposure assessment, a number of 3 measurements is enough On the day before monitoring determine in each SEG at random a worker in 3 consecutive shifts (e g the Day-, Evening- and Nights-shifts ) If 1 or more measurements are exceeding the exposure hmtt, the exposure profile is judged as unacceptable Take control-measures or reassess the exposure profile It can occur that the measured shift was not a normal (normative) day If you can make it plausible that the high concentration is not representative for normal operations, you can skip the result and take another measurement If it appears that the mean concentration of the 3 measurements is above the 10% of the exposure limit, 3 more measurements should be performed How to judge the results of these 6 measurements is described in chapter 7, "Conclusions of the assessment of occupational exposure to Dust (see also flowsheet in attachment 4) 6.7.3. Periodic measurements If after the initial monitoring, a SEG is judged as acceptable, mostly periodic measurements must be organized The aim is to verify on a regular base if the exposure conditions didn't change and/or if technical exposure control measures are working properly ABDOOO19395 18 Version 1 07 01 2002 In many countries the seasons will have some influence on the level of exposure But also the day, evening and night-time periods within 24 hours can have considerable different exposures either due to weather changes or to work practice differences In case of dust it is suggested that the measurement strategy for some exposure profiles is based on measurements in 2 seasons and in the different shifts The mean concentration of the exposure profile of the SEG will decide about the frequency of the measurements Mean concentration is > 10% and < 100% of exposure limit, For a SEG with a mean concentration greater or equal to 10% and lesser than 100% of the exposure limit, the following measurement strategy should be performed 1 Establish every half-year one day of monitoring, e g monitor on February and August 5th 2 On the day before monitoring determine in each SEG at random a worker in 3 consecutive shifts (e g the Day-, Evening- and Nights-shifts) 3 Carry out the measurements (also if there are less working activities) on that specific day and shift with the at random determined worker But keep in mind that not the specific worker is important, but the function or activity that that worker is carrying out 4 Calculate for the 6 measurements (for every SEG), the arithmetic mean concentration, verify if the distribution is log-normal or normal and calculate the probability of exceeding the exposure limit and judge if the exposure is acceptable (see chapter 7) Of course each set of 3 measurements can be evaluated on the acceptability, but for the evaluation of the long-term average, you need in this case 6 measurements (see chapter 7) Mean concentration is < 10 % of exposure limit For a SEG with an mean concentration lower than 10 % of the exposure limit, periodic sampling is not necessary ABDOOO19396 19 Version 1 07 01 2002 7. CONCLUSION OF THE ASSESSMENT OF OCCUPATIONAL EXPOSURE 7.1. INITIAL MONITORING 1 If one or more of the exposure results is exceeding the limit value, the exposure is unacceptable The reasons for this should be identified and appropriate measures to control the overexposure should be implemented immediately After appropriate measures have been implemented or new measurements are done, repeat the judgement of the acceptability of the exposure profiles 2 If the mean exposure concentration is below 10% of the limit value and it can be shown that these results are representative for the long-term workplace conditions, the periodic measurements can be omitted In such cases a regular check is required in order to verify if that conclusion is still applicable The exposure isacceptable 3 If the mean exposure concentration is above 10% of the limit value, the exposure is uncertain Perform with a minimum of 6 measurements a statistic evaluation and judge if the exposure is acceptable or unacceptable This statistical evaluation is the same as described in 7.2 "Periodic monitoring". 7.2. PERIODIC MONITORING Usage of statistics in judging quantitative monitoring data To make the decision if an exposure is acceptable, we must answer two questions a) Is the SEG exposure profile adequately characterised 9 b) Is the probability that the exposure exceeds the limit low enough 9 7.2.1. Judge if the exposure profile has a log-normal distribution. If you must reject a distribution on its log-normality or normality characteristics, it is possible that the exposure profile is not adequately characterised for this SEG Maybe the SEG you are examining contains two or more different exposure profiles In this case you must divide the SEG in two or more new SEGs and re-start the assessment 7.2.2. Calculate the probability of exceeding OEL To determine the probability of exceeding the exposure limit, the lognormal distribution model is a common proposed statistical model Specific software especially for industrial ABDOOO19397 20 Version 1 07 012002 hygiene monitoring, like Altrex, Hyginist and LogNormal2 are useful to check the hypothesis of lognormal distribution and to determine the probability of exceeding the exposure limit A simple but effective statistical tool that is developed by members of the AIHA is available together with the book3) Strategy for Assessing and Managing Occupational Exposures, 1999 In annex 6 an example of a statistical evaluation is given 1 Ifthe probability of exceeding the exposure limit is less than 0,1% and it can be shown that these values are representative for the long term workplace conditions the periodic measurements can be omitted 2 Ifthe probability of exceeding the limit is between 0 1 and 5%, repeat the next set of compliance measurements within 52 weeks 3 Ifthe probability of exceeding the exposure limit is >5% The reasons for this should be ldertified and appropriate measures to control the overexposure should be implemented immediately Repeat the measurements after appropriate measures have been implemented 7.2.3. How to cope with nondetectable values in a statistical evaluation? It is a common problem for industrial hygienist to select a valid way of dealing with those samples reported to contain nondetectable values There are different methods that are described in literature The Maximum Likelihood Estimation (MLE) method, the Regression method and the 2 simpler alternatives involved the substitution of the detection limit (L) by L/2 or LA/2 Because not every one has a dedicated statistical evaluation program, it is recommended to use the L/V2 substitution method For example a detection limit of 0 1 mg/m3 gives a substitution of 0 I/V2 = 01/ 1 41=0 07 mg/m3 ABDOOO19398 21 Version! 07 012002 RECORDKEEPING AND REPORTING It is very important that all relevant information of each exposure assessment is recorded and included in a summary report The report should contain - The job titles and a accurate description of the tasks undertaking the assessment and the measurements - description of the workplace factors, including the task and process conditions during the measurements, SEG - the sampler type and flowrate, the calibration - sampling method (personal, fixed point) - the measurement procedure - the time schedule (date, start and end of sampling) - the occupational exposure concentration - details of quality assurance (use of blanks, ) - result of the comparison with the limit value - Personal Protection Equipment (PPE) worn - any abnormal conditions - in the annex of the report the primary analytical data as measurement time, pump velocity, total volume of air sampled, concentration dust (PVC) on the filter A record of files (containing a wide array of relevant information) should be maintained during at least 30 years for easy retrieval of information on specific surveys and for use in epidemiologic studies ABDOOO19399 22 Version 1 07 01 2002 LITERATURE - EU: European directive (89/391) "FrameworkDirective on the introduction of measures to encourage improvements in the safety and health ofworkers at work " European Standard EN 689 \ CEN "Workplace atmospheres guidancefor the assessment ofexposure by inhalation to chemical agentsfor comparison whit limit values and measurement strategy" - European Standard EN481, ISO 7708 Workplace atmosphere-specificationsfor conventionsfor measurement ofsuspended matter - European Standard EN482 "Workplace atmospheres General requirements for the performance ofprocedures for measurements ofchemical agents", 1994 - EH31 \ HSE "Control ofexposure to polyvinyl chloride dust", 1982 - NIOSH method 500, Nuisance dust, total - NIOSH method 600, Nuisance dust, respirable - MDSH 14/3, HSE, 2000 "General methodsfor the gravimetric determination ofrespirable and total inhalable dust" 1) "A collaborative European study ofpersonal aerosol sampler performance" Ann occup Hyg, Vol 41 N02 ppl35-153, 1997 2) Evaluation ofSix Inhalable Aerosol Samplers, AJHAJ, 61 506-516 3) Strategyfor Assessing and Managing Occupational Exposures, AIHA:/999 4) Vergehjkend veldonderzoek van IOMen PAS-6 stofmonsternemer, H Kromhout LUW Wageningen, e a, Tijdschrift voor toegepaste Arbowetenschap 10 (1997) nr 1. 5) Adjustment ofPermissible Exposure Values to Unusual Work Schedules, A1HAJ (62( September/Oktober 2001, Jules Brodeur, e o Appendix 1 Inhalable dust samplers ABDOOO19400 Version 1 07 01 2002 Inhalable dust samplers Samplers of inhalable dust should comply with the standardised conventions for health-related sampling of aerosols in workplaces (EN481, ISO 7708) Given is for each sampler, the manufacturer, filter diameter, flow rate of the pump, inlet position of the opening, recommended correction factors related to the degree of wind speed (m/s) on the workplace Eight samplers are tested in a European studvl), this study has suggested using a correction factor in relation with the wind speed Sampling with a wind speed ofmore than 1 m/s is not recommended In another study2) a new RespiCon 3-stage sampler was tested with 5 other samplers With the RespiCon the respirable, thoriac and inhalable fractions can measured For the inhalable fraction the sum of the 3 filters must be calculated The new Button sampler is not yet tested, in the stud^only a prototype was tested with a different sample flow But by the manufacturer this sampler follows closely the ACGIH/ISO/NEN criteria 7-hole personal sampler (UK) Manufacturer Casella, SKC and JS Holding filter 25 mm flow rate 2 1/min Inlet position front Correction factor 0-0,5 m/s = 1,0 0,6 -1 m/s = 1,2 Button Aerosol Sampler (US) Manufacturer SKC filter * 25 mm flow rate 4 1/min Inlet position 360 Correction factor not tested in EU study CIP10-I personal sampler, incl. pump (F) Manufacturer Arelco ARC filter porous foam plug mm flow rate 10 1/min Inlet position up Correction factor 0-0,5 m/s = 1,1 0,6 -1 m/s = 1,15 Closed-face 37 mm polystyrene cassette (SE) Manufacturer Millipore filter 37 mm flow rate 2 1/min Inlet position below Correction factor 0 - 0,5 m/s = 1,0 0,6 -1 m/s = 1,2 Appendix 1 Inhalable dust samplers ABDOOO19401 2 GSP personal sampler (D) CIS sampler Manufacturer Strohlein (GSP), BGI CIS) filter 37 mm flow rate 3 5 1/min Inlet position front Correction factor 0 -0,5 m/s = 1,0 0,6 -1 m/s = 1,0 IOM Personal inhalable sampler (UK) Manufacturer SKC filter 25 mm flow rate 2 1/min Inlet position front Correction factor 0 - 0,5 m/s = 0,9 0,6 - 1 m/s = 1,0 Open-face 37 mm polystyrene cassette (US) Manufacturer Millipore filter 37 mm flow rate 2 1/min Inlet position below Correction factor 0-0,5 m/s = 1,15 0,6-1 m/s = 1,15 PAS-6 personal sampler (NL) Manufacturer several manufacturers filter 25 mm flow rate 2 l/min Inlet position front Correction factor 0 - 0,5 m/s = 1,0 0,6 -1 m/s = 1,25 PERSPEC personal sampler (IT) Manufacturer Lavoro e Ambiente filter 47 or 50 mm flow rate 2 1/min Inlet position below Correction factor 0 - 0,5 m/s -- 1,0 0,6 - 1 m/s = RespiCon Sampler Model 8522 (US) Manufacturer TSI Inc filter 3 x 37 mm flow rate 3,1 1/min Inlet position 360 Correction factor not tested in EU study Version 1 07 01 2002 ABDOOO19402 Appendix 3 Analytical method for chlorides Version 1 07 01 2002 Respirable dust samplers A sampler of respirable dust should comply with the standardised conventions for health-related sampling of aerosols in workplaces (EN481, ISO 7708) There are a 7 samplers in use, which comply with this standardisation, they are mentioned in alphabetic order CIP10-R personal sampler (France) (mcl pump) Manufacturer Arelco ARC filter porous foam plug mm flowrate 101/mm Dorr-OliverlO-mm nylon cyclone (US) Manufacturer e g Sensidyne BDX 99R filter 25 or 37 mm flowrate 1,71/mm GS Respirable Dust Cyclone (US) Manufacturer SKC filter 25 or 37 mm flow rate 2 75 1/mm SIMPEDS-cyclone (UK) Manufacturer Casella, SKC filter 37 mm flow rate 2 2 1/min Respirable Dust Aluminum Cyclone (US) Manufacturer SKC filter. 25 mm or 37 mm flow rate 2,5 Vmm RespiCon Sampler Model 8522 (US) Manufacturer TSI Inc filter 3 x 37 mm ( 1 filter for the respirable fraction) flowrate 3,1 1/min Inlet position 360 De methode wordt op dit ogenbhk gerapporteerd. ABDOOO19403 Appendix 4 Flowsheet Judging the exposure profile Version 1 07 01 2002 Appendix 5 Glossary GLOSSARY ABDOOO19404 Version 1 07 01 2002 ACGIH American Conference ofGovernmental Industrial Hygienists CEN Comite Europeen de Normalisation COHYG Coordinateur en Hygiene Industrielle EN European Norm HSE Health and Safety Executive Inhalable the mass fraction oftotal airborne particles which is inhaled through the nose and mouth ISO International Organizationfor Standardization m/s meter per second MAC Maximaal Aanvaarde Concentratie (Netherlands) MAK Maximal Arbeitsplatzkonzentration (Germany) mg/m3 milligramper cubic meter NIOSH National Institute for Occupational Safety and Health OEL Occupational Exposure Limit (United Kingdom and as a common used name) OSHA Occupational Safety and Health Administration (US) LOD Limit ofDetection LOQ Limit ofQuantitaion PEL Permissible Exposure Limit (United States, OSHA) PNOC Particulates Not Otherwise Classified PPE Personal Protection Equipment PVC polyvinyl chloride Respirable The massfraction ofinhaledparticles penetrating to the uncihated (alveolar) airways SEG Similar Exposure Group TLV Threshold Limit Value (United States, ACGIH) TWA Time Weighted Average * Appendix 6 Statistical Evaluation ABDOOO19405 Version 1 07 012002 STATISTICAL TOOL A simple but effective statistical tool that is developed by members of the AIHA and is available together with the book^ In this annex an example of statistical evaluation is given Example PVC-dust The statistical evaluation of 6 personal 8 hours TWA measurements of inhalable PVC in a PVC production plant, see figure 1 The exposure limit of inhalable PVC = 10 mg/m3 TWA 8 hours The concentrations are 4.95,6.54, 0.25, 3.65,1.06, 0.95mg/m3 As described before the following evaluations are important Test for distribution fit Is the exposure profile log-normal or normal If yes, the percent above the exposure limit (% > OEL) must be less than5% to be acceptable In figure 1 of this Annex the statistical evaluation is shown of the 6 PVC dust measurements The distribution fit is = log-normal and normal Percent above the exposure limit (% > OEL) = 8,174% = unacceptable Appendix 6 Statistical Evaluation ABDOOO19406 2 Version 1 07 01 2002 Example Vinylchlonde The statistical evaluation of 6 personal TWA 8 hours' measurements of PVC in a PVC production plant PLANT FACTORY S.E.C. SUBSTANCE PERIOD "D2T 355" TIB" "095" Industrial Hygiene Statistics Example piaasa aa ncrai!riPiU5 PVC production Iravallleurs de cnargement PVC 2000 'runuuyanjujuii) Marrun(max) Mnrrun(rnn) i%nge Percent abwe OB. (%*C&) raaai------------------ Standard dewafxn (s) fogtrandrrTBddata(LN) Sid deuacn cf logtransfonred data (LN) Gecrretric mean (G^ Geometnc standard dewdicn (GSC$ Sadipl* Numtoir Logprobabillty Plot and Least-Squares Best-Fit Line MLMHLWWWdWUSlftiisin-a t66arT--^-- T9fi LCL,m tstattsOcs 0812 UCL^g* -1 sHb&cs 496 95Hi FercanUleTZ------------------------------------- 7TJ7E Linear Probability Plot and Least-Squares Best-Fit Line I 99% II 98% I 1199%. / I*/ 75% 5C% 25% 1 <, ick 17%- Corcerttratlcn 10 100 / 190% I jH't 1 75% 150% 045 04 I 0.35 ^ Idealized Lognormal Distribution 4M and CK%le U3 44 025 1I 2i9i%i 110% 02 ais 0.1 T.. ii%* 005 0 -10 Cfrcentratiui 10 15 0 10 20 cefcantrattn 50 60 70