Asbestos Workers Database: Summary Statistics

Transcription

1 Harpur Hill, Buxton Derbyshire, SK17 9JN T: +44 (0) F: +44 (0) W: Asbestos Workers Database: Summary Statistics HSL/2007/05 Project Leader: Author(s): Science Group: Derek Morgan Anne-Helen Harding Johannah Wegerdt Health Sciences Crown copyright (2006)

2 ACKNOWLEDGEMENTS The authors would like to thank the whole team working with the Asbestos Workers Database, and in particular Anna Buttrill, Claire Collins, Carl Gartside, and Rachel Sigsworth. The authors would also like to thank Andy Darnton and Damien McElvenny from HSE s Statistics Branch, with whom the authors have had many discussions on the Asbestos Workers Database, and for their helpful comments on the report. ii

3 CONTENTS 1 INTRODUCTION METHODS Duplicate records Dates Job categories Data checking Length of time in the survey Smoking status Summary statistics RESULTS Cleaning All workers in the Asbestos Survey From From Removal Workers Manufacturing workers Other workers All workers smoking habits DISCUSSION APPENDICES BIBLIOGRAPHY GLOSSARY iii

4 LIST OF FIGURES Figure 1 Flow chart...6 Figure 2 Number of medical examinations by year of examination, Figure 3 Number of medical examinations each worker has undergone, Figure 4 Number of medical examinations each worker has undergone for workers who entered the survey post-1987 ( )...8 Figure 5 Comparison of percent workers in manufacturing, stripping or Other job categories at 10-year intervals, Figure 6 Number of workers in each age category by year of examination, Figure 7 Number of workers in each job category by year of examination, Figure 8 Number of removal workers using wet or dry stripping methods, Figure 9 Number of removal workers in each job type by year of examination, Figure 10 Number of removal workers using the different types of respirator by year of examination, Figure 11 The number of removal workers and the mean number of hours spent stripping per week, by year of examination, Figure 12 Number of workers in the manufacturing sectors by year, Figure 13 Number of workers in Other industry sectors by year of examination, Figure 14 Number of Other asbestos workers using the different types of respirator by year of examination, Figure 15 Frequency that Other asbestos workers work with loose asbestos insulation by year of examination, Figure 16 Other asbestos workers: frequency of contact with asbestos containing materials, Figure 17 The smoking status of asbestos workers by year of examination, Figure 18 Smoking status of licensed asbestos workers at their first examination during the period , by industry sector iv

5 LIST OF TABLES Table 1 Number of data points checked against original paper records...5 Table 2 Data points checked...5 Table 3 Length of time (years) spent in the Asbestos Survey, according to job category at the first medical examination, Table 4 Length of time (years) spent in the Asbestos Survey for workers joining the survey after the introduction of CAWR, according to job category at the first medical examination, Table 5 Number of medical examinations by age category and by year of examination, Table 6 Number of medical examinations by year and sex, Table 7 Number of medical examinations by age category at first examination, Table 8 Number of medical examinations by year of examination and job category, Table 9 Removal workers: age at the first medical examination by sex ( ) Table 10 Number of removal workers in each job type by year of examination, Table 11 Length of time (hours) removal workers spent stripping each week by year of examination, Table 12 Manufacturing workers: age at the first medical examination by sex, Table 13 Length of time (hours) manufacturing workers spent each week in a respirator zone by year of examination, Table 14 Length of time (hours) manufacturing workers spent each week in an asbestos area by year of examination, Table 15 Other workers: age at the first medical examination by sex, Table 16 Number of Other asbestos workers reporting contact with asbestos containing materials by year of examination, Table 17 Smoking status of asbestos workers by year of examination, Table 18 Smoking status of licensed asbestos workers at first examination during the period , by age category and sex Table 19 Cigarettes smoked per day by year of medical examination, Table 20 Number of cigarettes smoked per day by sex and by age at first examination, Table 21 Number of cigarettes smoked per day by industry sector, v

6 EXECUTIVE SUMMARY Objectives This report summarises the data collected by the Asbestos Workers Survey during the period , as requested by The Disease Reduction Programme. Main Findings The number of medical examinations completed declined from 8,057 in 1988 to 4,814 in At the same time there was a shift from the manufacturing into asbestos removal and stripping sectors. Approximately 60% of workers joining the survey after 1987 attended only one medical examination, while 24% attended between 2 and 5 medicals. Compared with the general population, a high proportion (average 52%) of asbestos workers were current smokers. By 2004, there were very few workers (1%) in the manufacturing sectors. Among removal workers, the use of wet stripping methods increased between 1988 and 2004, and the majority of workers used a full-face, airstream or positive pressure respirator. Although the number of removal workers decreased, the number of hours spent per week on stripping activities increased by 50% from 1998 to Among Other asbestos workers, there was a sharp increase in the number of workers in the miscellaneous sector in 1999, and by 2004 this sector was larger than both the shipbuilding and construction sectors. Most Other asbestos workers rarely came into contact with loose asbestos insulation or broken asbestos insulation board, but the frequency of contact with other asbestos material increased between 1988 and The total number of medical examinations undertaken between 1988 and 2004 was 83,282. The number of licensed asbestos workers examined each year decreased from 8,057 in 1988 to 4,814 in The majority of workers (57%) had one medical examination during the lifetime of the Asbestos Survey ( ). The maximum number of examinations recorded for any individual was 19; one individual was examined 19 times, and five individuals were examined 16 times. - For workers who joined the survey after the introduction of the Control of Asbestos at Work Regulation (CAWR), the maximum number of examinations any individual underwent was 12 (one individual). For these workers, 69% attended only one medical. - There was a marked change in the proportions of workers in the three job categories over the lifetime of the survey. The proportion of workers in manufacturing decreased from 87% in 1972 to 20% in 1988 and 1% in 2004, while those in stripping/removal increased from 0.5% in 1972 to 71% in 1988 and 85% The majority of workers were male (98%). There were small differences between the main job categories: 91% of workers in manufacturing were male, 99% of workers in stripping/removal, and 96% of Other asbestos workers were male. - The most prevalent age group was years. Very few workers were aged less than 20 or more than 55 years. The mean age of workers at their first medical examination in manufacturing was 39 years (standard deviation 12), in stripping/removal 34 years (sd 10) and in Other asbestos work 38 years (sd 11). vi

7 - The number of examinations on manufacturing workers declined steadily from 1,589 in 1988 to 58 in The largest proportion of manufacturing workers (63%) were employed in the sector manufacturing asbestos/rubber/resin/bitumen mixtures. Within all manufacturing sectors, the proportion of maintenance workers increased from 16% in 1988 to 53% in The mean length of time spent per week in a respirator zone declined from 9 hours in 1988 to 6 hours in 2003 and 0.5 hours in 2004, and the median time was 0 hours for all years except 2002 when it was 1 hour. The mean length of time spent per week in an asbestos area for the period was relatively stable and was 25 hours while the median was 35 hours. - Stripping/removal workers were largely (73%) involved in stripping and/or encapsulation activities rather than supervising or other activities. There was a shift from predominantly dry stripping methods (62%) in 1988 to wet stripping (90%) in The most commonly used respirator was a positive pressure mask or blouse (78%) followed by a full-face unpowered mask (19%). The mean time spent stripping per week rose from 17 hours in 1988 to 22 hours in 2004, and the median rose from 10 hours to 21 hours in the same period. The increase in hours occurred mainly between 1998 and The majority of workers in the Other asbestos job category were employed in the building and construction sector until 1997 (range 67% to 91%). In 1988 the percentage in this sector fell to 43% and by 2004 building and construction represented 22% of Other asbestos jobs. The mean percentage working in the shipbuilding sector was 27% (range 9% and 40%) during this period, while the percentage in miscellaneous work increased from less than 1% prior to 1998 to 22% in 1999 and 60% in The most commonly used types of respiratory protection varied from year to year. Overall, the most commonly used methods were the half-face mask (31%), followed by minimal protection (19%), and no protection (17%). A positive pressure mask or blouse was used by 12% and 13% used an air-stream helmet. In the Other asbestos job category, 41% of workers were never exposed to loose asbestos insulation or broken up asbestos insulation board. For those who were exposed, there was a relatively even distribution between daily, weekly, monthly or yearly exposure. For other asbestos containing materials, the largest proportion of workers reported coming into contact with intact insulation board (41%), followed by other materials containing asbestos (36%), asbestos cement (30%), and brake and clutch plates (7%). The frequency of exposure to other asbestos containing materials increased between 1988 and For all years between 1988 and 2004, the majority of workers reported that they were current smokers (52%), while 20% were ex-smokers and 28% were non-smokers. In Great Britain, 26% of men were smokers in 2004 (Office of National Statistics, 2006). The majority of women reported they were ex-smokers or non-smokers in all age groups except those aged less than 20 years, who reported they were current smokers. Men under 45 years were predominantly current smokers, while men over 55 years were mainly ex-smokers or non-smokers. Workers in the stripping and textile sectors had the highest proportion of current smokers (58% and 55% respectively). The number of cigarettes smoked per day decreased slightly during this period, from a mean of 17 cigarettes per day (sd 8.2) in 1988 to 15 cigarettes per day (sd 7.6) in Men tended to smoke more than women (16 cigarettes per day compared to 14). vii

8 Recommendations From late-2006, the survey data will be collected using a revised questionnaire. Many of the difficulties identified in the current MS75 are addressed in the new questionnaire. However when the new questionnaire is introduced, asbestos workers will again be given the choice of opting out of the survey and the survey will no longer be a census. It will be important to monitor the proportion of licensed workers who choose not to participate in the survey since the representative nature of the survey will be affected if large numbers of workers opt out. Nevertheless, by continuing data collection, the Asbestos Survey will provide the means whereby the effects of HSE interventions relating to asbestos exposure in the workplace can be monitored. viii

9 1 INTRODUCTION The Asbestos Survey was established in 1971, following the introduction of the 1969 Asbestos Regulations (AR) (Hutchings and Hodgson, 1995). The regulations applied to every process that used asbestos or any article that contained asbestos, to ensure that exposure to asbestos fibres was minimised for all workers. Workplaces encompassed by the regulations were recruited into the survey until the late 1970s, and all employees at each workplace were eligible for inclusion. The workers in the survey attended a voluntary medical examination at two yearly intervals, or if they changed jobs within the asbestos industry. At the time of the examination, they completed a questionnaire with details of smoking history, occupational history and duration of exposure to asbestos. In 1983, the Asbestos (Licensing) Regulations (ALR) came into force. These regulations covered all work involving asbestos insulation and asbestos coating but did not include asbestos cement or asbestos board. Individuals undertaking work with listed types of asbestos materials had to possess a licence issued by the Health and Safety Executive. The regulations required all licensed workers to be medically examined before beginning this work, and to be re-examined at least once in every two years while in this work. Those workers examined under ALR were included in the Asbestos Survey. The 1987 Control of Asbestos at Work Regulations (CAWR) superceded the 1969 AR and the 1983 ALR (Hutchings and Hodgson, 1995). From 1 st March 1988, all individuals who were occupationally exposed to asbestos above a defined action level were required to undergo statutory medical examinations. Premises covered by the 1969 AR but where no workers were exposed to asbestos above the action level were no longer required to forward data for inclusion in the Asbestos Survey although they could continue to do so on a voluntary basis. Under CAWR, employers have a duty to have employees covered by the regulations medically examined within two years of beginning work with asbestos, and re-examined at least biennially thereafter. The medical examinations were conducted by HSE appointed doctors. At the examination, workers complete a revised questionnaire, which includes questions on their job, exposure to asbestos, personal protective equipment, and smoking history. Since 1987, the Asbestos Survey has been a census of licensed asbestos workers. The Asbestos Survey was established and managed by the Health and Safety Executive until the end of From that time on, the Health and Safety Laboratory was contracted to manage, and analyse the data from, the Asbestos Survey. The current report relates largely to the period covered by CAWR, and provides a summary of the data contained in the Asbestos Survey database. 1

10 2 METHODS Licensed asbestos workers are required to attend a medical examination every two years. While attending this examination, the Asbestos Survey questionnaire (Appendix 1) is completed. Data collected in these questionnaires for the period 1988 to 2004 were analysed for the main part of this report. Data from the whole survey, beginning in 1971, were analysed for those sections where the complete record was essential, for example when tabulating the number of medical examinations undergone by each worker, or when the long-term trend was examined. The survey data entered since 1992 had not been analysed previously and required cleaning. There were three major issues to be addressed during the cleaning process, namely duplicate records, incorrect dates, and inconsistencies between variables describing an individual s job. 2.1 DUPLICATE RECORDS Duplicate records were identified on the basis of identical date of birth, surname and sex, but different National Insurance numbers. The records identified as potential duplicates were checked, by two independent researchers (A-HH and JW) using additional information, in order to identify sets of records that were likely to belong to one individual. Additional data used for this comprised forenames, birth place, general practitioner s name, geographic region, job code, job category, company name, date of first ever exposure to asbestos, date of first exposure to asbestos in current employment, and date of first medical examination in the survey. The paper records of those sets, which still appeared to belong to one individual, were checked for data entry errors (n = 724). 2.2 DATES Dates were sorted and impossible dates, such as a date of birth 16-June-0953, were included for checking. For other dates, certain assumptions had to be made so that the validity of dates entered in the database could be checked:- Workers could not have an examination date before 1971, the start of enrolment into the survey following the implementation of Asbestos Regulations in May The minimum age for a medical examination and for the first occupational exposure was taken to be the same as the minimum school leaving age. These were 12 y until 1921, 14 y until March 1947, 15 y until August 1972, and 16 y from September 1972 (Department for Education and Skills). The maximum age for a medical examination and for the first occupational exposure to asbestos was taken to be 70 y before 1925, 65 y from 1925, and 60 y for women from These were based on the state pension age, although there is no statutory retirement age in the UK (BBC, 2002). The first exposure to asbestos in the current job could not predate the date of the first ever occupational exposure to asbestos. Asbestos Board dates could not precede the first ever occupational exposure to asbestos. Death and cancer registration dates could not occur before the date of birth. The paper records were checked for any dates violating these assumptions. 2

11 2.3 JOB CATEGORIES Asbestos workers were coded to three main job categories, namely manufacturing (M), stripping/removal (S), and other (O). New regulations covering asbestos workers came into force after the start of the survey (ALR 1983 and CAWR 1987), and the data collection forms changed accordingly. Prior to 1983, the only information on the type of work undertaken came from the job code. Under ALR, no information on job category or job code was collected. However, from 1988 onwards, the questionnaire included information on job type in the panel code (M, S, or O; Appendix 1, section C), a job code (Appendix 1 and Appendix 2, Panels M/S/O), and detailed questions relating to work practices (Appendix 1, Panels M/S/O). For workers post 1987, issues that had to be resolved occurred when the information on the completed questionnaires was inconsistent, for example M was entered in the panel code in Section C (Appendix 1), a stripping job code was entered in Panel M relating to manufacturing, and details relating to manufacturing were recorded. Rules for allocating workers to job category were defined as follows:- From 1988 onwards, workers with no information on job category (M, S, or O) and with missing job code information were allocated to S (n = 910), since the majority of workers were involved in stripping/removal of asbestos following CAWR. Cross-tabulations showed that panel code and detailed responses relating to work practices were consistent for all workers. For 2,419 workers, the job code was inconsistent with the job category. For these workers, the job category indicated by the panel code was assumed to be correct. Job codes (Appendix 2) were used to allocate workers to the corresponding industry sector, for example textile manufacture or asbestos cement mixture board and pipe manufacture. Those workers with inconsistencies between their job code and their panel code were excluded from the analysis of industry sector (n = 2,419). 2.4 DATA CHECKING Data in the database that appeared to be impossible or violated assumptions were checked against the original paper records. In addition, the paper records of a random sample of 20 workers with inconsistent panel codes and job codes (section 2.3) were checked. Altogether 1,582 data points were checked in the paper records belonging to 1,369 workers. If the entry in the database was the same as the paper records, then the database was not changed. The entry in the database was changed when it differed from the paper record. A record was kept of all changes made. 2.5 LENGTH OF TIME IN THE SURVEY The length of time an individual spent in the survey was estimated as the time between the dates of the first and the last medical examinations recorded. Any time spent working with asbestos after the last medical examination recorded could not be included in this estimate. Consequently, for workers with only one medical examination, the time spent in the survey was assumed to be 0 years. 2.6 SMOKING STATUS A number of workers reported they were non-smokers but also recorded age when they started smoking, age when they stopped smoking and/or the number of cigarettes smoked per day, on the questionnaire. These individuals (n = 161) were re-allocated to the ex-smoker category. 3

12 2.7 SUMMARY STATISTICS The summary statistics and graphs were produced using Stata Version 8. All analyses were restricted to men and women aged 15 to 84 years, and to medical examinations undertaken between 1988 and 2004, or between 1971 and 2004 for those analyses covering the whole survey period. The number of individuals included in the calculation of a particular statistic varied, depending on how many valid responses were given on the questionnaires. The majority of statistics calculated relate to the period post However, to put these in context, a few summary statistics relating to the lifetime of the survey were included. 4

13 3 RESULTS The total number of survey questionnaires recorded in the database from the beginning of the survey was 205,243. When restricted to examination dates falling between 1971 and December 2004 (inclusive) and to individuals aged 15 to 84 years (inclusive) the number recorded was 203,527. The number of examinations undertaken between 1988 and the end of 2004 on individuals aged 15 to 84 years, was 83,282. Altogether, 38,838 men and 832 women had at least one medical examination during the latter period. 3.1 CLEANING As discussed in the Methods section (pages 2 to 3 of this report), the data were cleaned. Figure 1 charts the data-cleaning process from the original data to the cleaned data. The original snapshot of the database had 97,799 individuals with 205,243 examinations. The original paper records were reviewed for the data that were flagged for checking during the cleaning process. When the data differed between the paper copy and that on the computer, the computer version was changed. Altogether 1,582 data points were flagged for checking on 1,369 workers (some workers had more than one data point to be checked). Table 1 summarises the number of data points checked and changed accordingly. Table 2 presents the reasons data were checked and the number of data points that were changed in each category. After checking the original records on 1,369 workers and their medical examinations, and placing the restrictions on some of the workers (for example with minimum and maximum first examination age), there were 39,670 workers and 83,282 medical examinations to analyse for the period (Figure 1). Table 1 Number of data points checked against original paper records Total data points flagged for cleaning/checking 1,582 Number of data points left unchanged 1,385 Number of data points changed 197 Table 2 Details of data points checked and changed Total checked Total changed Duplicates Date of birth Dates (all variables with dates) Mesothelioma Sample of Panel Codes 20 5 Other 14 1 Total 1,

14 Dataset 2005 Individuals (n=97,799); Exams (n=205,243) Cleaning and checking n = 1369 Exclusion process Age <15 years: n= n=9 >84 years: n= n=9 Exam date pre 1971 n= 39 post 2004 n= 1652 FINAL DATASET Individuals (n=96,728) n=57, n=39,670 Figure 1 Flow chart Exams (n=203,527) n= 120, n= 83,282 6

15 3.2 ALL WORKERS IN THE ASBESTOS SURVEY The summary statistics for all workers are presented for the period and for the period The statistics for the period are provided to allow long-term trends to be examined, and to follow individual workers throughout the time they were part of the survey FROM Figure 2 shows the number of medical examinations undertaken each year since the beginning of the survey. The largest number of examinations was carried out in 1985 (n = 13,018) and then steadily decreased, reaching a minimum in 1996 (n = 3,575). Thereafter the number of examinations increased again until 2000, when they levelled off at about 4,800 per year Number of examinations 0 5,000 10,000 15,000 Number of examinations = 203,527; number of workers = 96,700 Figure 2 Number of medical examinations by year of examination, A summary of the number of medical examinations that each worker has undergone between 1971 and 2004 is presented in Figure 3. Most workers had one medical examination only (57%) between 1971 and The maximum number of examinations recorded for any individual was 19 (n=1), and five individuals had 16 examinations. The mean number of examinations taken by a worker was 2.1 (median = 1). The equivalent for those workers who joined the survey after the introduction of CAWR (Figure 4) shows a similar pattern. The maximum number of examinations any of these workers had was 12, and the mean number of examinations taken by a worker was 1.6 (median = 1). 7

16 Number of workers 0 20,000 40,000 60, Figure 3 Number of medical examinations each worker has undergone, Number of workers 0 5,000 10,000 15,000 20,000 25, Figure 4 Number of medical examinations each worker has undergone for workers who entered the survey post-1987 ( ) 8

17 Figure 5 illustrates job categories at 10-year intervals (1972 to 2002). The pie charts show a clear shift in industry type from manufacturing in the 1970 s to stripping and removal two decades later, with workers in Other asbestos work maintaining a similar proportion throughout the whole period. In 1972 the asbestos industry was dominated by the manufacturing sectors, with 97% of asbestos workers in manufacturing. By 2002, less than 2% of workers were in manufacturing and 85% were working in the removal/stripping sectors. The average length of time spent in the Asbestos Survey between 1971 and 2004 is summarised in Table 3. There were nearly 54,000 first medical examinations between 1971 and 2004 in stripping and removal work, followed by manufacturing (over 32,000 examinations). Manufacturing had the highest mean number of years in the industry (3.3 years) followed by removal/stripping (2.7 years), and Other (2.5 years). The overall mean for years spent in the survey was 2.9 years (sd 12 years). For those workers who joined the survey after the introduction of CAWR in 1988 (Table 4), the large majority of first examinations were on individuals in removal/stripping work. There was little difference between the three job categories in the mean number of years spent in the survey (overall mean 0.59 years, sd 1.8). Table 3 Length of time (years) spent in the Asbestos Survey, according to job category at the first medical examination, Job category Mean sd Median percentile percentile Count Manufacturing ,542 Stripping ,881 Other , th 75 th Table 4 Length of time (years) spent in the Asbestos Survey for workers joining the survey after the introduction of CAWR, according to job category at the first medical examination, Job category Mean sd Median 25 th percentile 75 th percentile Number of workers Manufacturing ,489 Stripping ,691 Other , FROM For the period , the largest number of examinations was done for both men and women in 1988, with the smallest number done in 1995 and 1996 (Table 6). The majority of the workers were men (range 97-99%), with 1,515 examinations undertaken on women and 81,767 on men (total 83,282 exams). The number of workers having examinations each year decreased between 1988 and 1995, before increasing steadily to 98 examinations for women and 4,716 examinations for men in Table 5 shows the number of medical examinations by age category and by year of examination (also shown in (Figure 6). It shows that most examinations were taken between the ages 20 to 49 (82%). Fewer examinations were done on workers aged under 20 or over 55 years. This pattern is similar 9

18 12%.5% 12% 19% 69% 87% Manufacturing Other Stripping 1972 (n = 3205) Manufacturing Other Stripping 1982 (n = 5986) 12% 16% 13% 1.9% 71% 85% Manufacturing Stripping Manufacturing Stripping Other 1992 (n = 4792) Other 2002 (n = 4770) Figure 5 Comparison of percent workers in manufacturing, stripping or Other job categories at 10-year intervals,

19 Table 5 Number of medical examinations by age category and by year of examination, Year of Age category examination < Total (2) 1,161 (14) 1,405 (17) 1,155 (14) 1,056 (13) 1,053 (13) 806 (10) 566 (7) 417 (5) 245 (3) 8, (2) 1,095 (14) 1,343 (18) 1,043 (14) 985 (13) 951 (13) 697 (9) 610 (8) 448 (6) 248 (3) 7, (2) 694 (11) 1,062 (17) 915 (15) 829 (14) 824 (14) 621 (10) 504 (8) 339 (6) 204 (3) 6, (1) 475 (9) 849 (16) 821 (16) 710 (14) 725 (14) 606 (12) 464 (9) 305 (6) 189 (4) 5, (1) 432 (9) 764 (16) 809 (17) 654 (14) 650 (14) 568 (12) 434 (9) 281 (6) 133 (3) 4, (1) 344 (8) 678 (16) 763 (18) 613 (15) 514 (12) 486 (12) 359 (9) 211 (5) 114 (3) 4, (1) 315 (8) 556 (14) 713 (18) 577 (15) 513 (13) 473 (12) 350 (9) 203 (5) 127 (3) 3, (1) 328 (9) 593 (16) 720 (19) 600 (16) 481 (13) 428 (11) 328 (9) 185 (5) 96 (3) 3, (1) 307 (10) 514 (14) 719 (20) 589 (16) 489 (14) 395 (11) 262 (7) 170 (5) 79 (2) 3, (2) 320 (8) 545 (14) 746 (19) 664 (17) 502 (13) 431 (11) 308 (8) 169 (4) 90 (2) 3, (1) 329 (8) 614 (15) 749 (18) 773 (19) 557 (13) 448 (11) 351 (8) 178 (4) 101 (2) 4, (2) 401 (10) 522 (13) 734 (18) 752 (18) 547 (13) 464 (11) 329 (8) 198 (5) 94 (2) 4, (2) 485 (10) 647 (14) 762 (16) 856 (18) 690 (15) 438 (9) 394 (8) 210 (4) 113 (2) 4, (2) 498 (10) 672 (14) 833 (17) 887 (18) 727 (15) 480 (10) 374 (8) 223 (5) 98 (2) 4, (2) 508 (11) 613 (13) 769 (16) 843 (18) 724 (15) 506 (11) 365 (8) 251 (5) 114 (2) 4, (2) 540 (11) 641 (13) 706 (15) 825 (17) 760 (16) 511 (11) 402 (8) 243 (5) 104 (2) 4, (2) 636 (13) 733 (15) 682 (14) 764 (16) 704 (15) 518 (11) 347 (7) 223 (5) 100 (2) 4,814 Total 1,510 (2) 8,868 (11) 12,751 (15) 13,639 (16) 12,976 (16) 11,411 (14) 8,876 (11) 6,748 (8) 4,254 (5) 2,249 (3) 83,282 Data are counts with row percentages in parentheses 11

20 Table 6 Number of medical examinations by year and sex, Year of examination Women Men Total (3) 7,854 (97) 8, (2) 7,422 (98) 7, (3) 5,934 (97) 6, (2) 5,085 (98) 5, (2) 4,696 (98) 4, (1) 4,073 (99) 4, (2) 3,812 (98) 3, (1) 3,786 (99) 3, (1) 3,535 (99) 3, (1) 3,792 (99) 3, (1) 4,107 (99) 4, (2) 4,052 (98) 4, (1) 4,613 (99) 4, (1) 4,834 (99) 4, (2) 4,716 (98) 4, (2) 4,740 (98) 4, (2) 4,716 (98) 4,414 Total 1,515 (2) 81,767 (98) 83,282 Data are counts with row percentages in parentheses Table 7 Number of medical examinations by age category at first examination, Age category Number of examinations Percent Cumulative percent <20 1, , , , , , , , , Total 39, Note: Restricted to workers aged < 85 years 12

21 for all years, except for 1988, 1989 and 2004 when there was a bigger proportion of 20 to 24 year olds. The mean age of workers attending their first medical examination during the period was 35 years (sd 11 years) (Table 7). Table 8 shows the number of medical examinations by year of examination (under CAWR) and job category. The total number of licensed workers examined each year nearly halved (59%) between 1988 and Throughout the period, the majority of workers categorized themselves as working in stripping and removal (76%). The proportions varied over time, but overall the proportion of workers in stripping increased, starting with 71% in 1988 and rising to 85% in 2004, with peaks in 2000, 2002, and 2004 of 85%. In the same period, the proportion that responded as working in manufacturing progressively declined from 20% in 1988 to 1% in Those categorised as Other varied throughout the period around its mean 13%. The percentage of workers in each job category by year of examination is displayed in Figure Number of workers 0 2,000 4,000 6,000 8,000 < Number of examinations = 83,282; number of workers = 39,672 Figure 6 Number of workers in each age category by year of examination,

22 Table 8 Number of medical examinations by year of examination and job category, Year of examination Manufacturing Stripping Other Total ,589 (20) 5,715 (71) 753 (9) 8, ,341 (18) 5,118 (67) 1,141 (15) 7, ,102 (18) 4,073 (67) 923 (15) 6, (18) 3,308 (64) 932 (18) 5, (16) 3,424 (71) 588 (12) 4, (14) 3,123 (76) 424 (10) 4, (12) 2,955 (76) 448 (12) 3, (7) 3,058 (80) 491 (13) 3, (7) 2,888 (81) 436 (12) 3, (4) 3,206 (83) 474 (12) 3, (5) 3,488 (84) 453 (11) 4, (2) 3,460 (84) 565 (14) 4, (2) 3,929 (85) 579 (13) 4, (2) 4,056 (83) 689 (14) 4, (2) 4,060 (85) 620 (13) 4, (2) 3,925 (83) 740 (15) 4, (1) 4,011 (85) 662 (14) 4,731 Total 8,283 (11) 63,795 (76) 10,920 (13) 82,998 Data are counts with row percentages in parentheses 14

23 Number of workers 0 2,000 4,000 6,000 8,000 Manufacturing Other Stripping Number of examinations = 82,998 Figure 7 Number of workers in each job category by year of examination, REMOVAL WORKERS The graphs and tables in this section present the data for removal and stripping workers in the period 1988 to 2004 (CAWR). Table 9 summarises medical examinations by age and sex. The mean age at first examination was 34 years (sd 10 years). The majority of workers fell within the year age range, and 99% of removal workers were men. Figure 8 shows a shift over time in stripping and removal methods from predominantly dry stripping methods (62%) in 1988 to wet stripping in 2004 (90%). The decline in dry stripping started in 1992, plateaued between 1996 and 1998 (inclusive), before the majority of stripping was done wet from 2000 on. The number of removal workers in each job type by year of examination is presented in Table 10 and in Figure 9. Most removal workers categorised themselves as doing stripping and/or encapsulation (total 73%). One exception was the year 2003, when only 59% reported working in stripping and/or encapsulation and 28% said they worked in Other work (compared to the overall mean of 14%). There was a slight decline in numbers that reported working in stripping and/or encapsulation between 1991 and 1997, when numbers dropped below The year the highest number of workers was reported for stripping and removal was The overall proportion of supervisors in the stripping and removal sector was 13%. 15

24 Table 9 Removal workers: age at the first medical examination by sex ( ) Age (years) at first examination Women Men Total <20 6 (1, 1) 1,013 (99, 3) 1,019 (100, 3) (2, 29) 5,012 (98, 16) 5,114 (100, 17) (2, 32) 5,812 (98, 19) 5,928 (100, 19) (1, 15) 5,266 (99, 17) 5,324 (100, 17) (1, 10) 4,463 (99, 15) 4,500 (100, 15) (1, 6) 3,404 (99, 11) 3,423 (100, 11) (1, 4) 2,366 (99, 8) 2,377 (100, 8) 50-6 (1, 2) 1,632 (99, 5) 1,638 (100, 5) 55-2 (1, 1) 860 (99, 3) 862 (100, 3) 60-1 (1, 0) 376 (99, 1) 377 (100, 1) Total 357 (1, 100) 30,204 (99, 100) 30,561 (100, 100) Data are counts with row and column percentages in parentheses Number of workers 0 1,000 2,000 3,000 4,000 Dry stripping W et stripping Number of examinations = 53,529 Figure 8 Number of removal workers using wet or dry stripping methods,

25 Table 10 Number of removal workers in each job type by year of examination, Year of examination 1988 Supervisor Stripping/ encapsulation Other Total 472 (14) 2,569 (74) 409 (12) 3, (13) 2,892 (77) 393 (10) 3, (14) 2,270 (77) 277 (9) 2, (15) 1,859 (75) 254 (10) 2, (13) 1,867 (74) 322 (13) 2, (12) 1,872 (79) 203 (9) 2, (13) 1,680 (78) 213 (10) 2, (13) 1,794 (81) 153 (7) 2, (12) 1,578 (72) 346 (16) 2, (13) 1,731 (74) 297 (13) 2, (12) 2,129 (74) 388 (14) 2, (10) 2,706 (79) 383 (11) 3, (13) 2,363 (72) 480 (15) 3, (12) 2,519 (71) 610 (17) 3, (14) 2,300 (67) 657 (19) 3, (13) 2,145 (59) 1,022 (28) 3, (11) 2,659 (71) 653 (17) 3,739 Total 6,386 (13) 36,932 (73) 7,060 (14) 50,378 Data are counts with row percentages in parentheses 17

26 The responses for different types of respirator used by removal workers are presented by year of examination in Figure 10. The most common type of respirator used was a positive pressure mask or blouse (78%), followed by a full-face unpowered mask (19%). Very few workers used no respiratory protective system, a minimal respirator or an air stream mask. Table 11 and Figure 11 summarises the time removal workers spent stripping each week (by examination year). The maximum number of hours spent stripping each week varied very little between 1988 and 2004 (range 80 to 98 maximum hours). The average number of hours increased over the period from 17 hours to 22 hours stripping each week in 2004, with a sharp rise in the number of hours worked per week occurring in The year with the lowest mean time spent stripping was 1994 (15 hours) and the highest was in 2002 (22 hours). The median rose from 10 in 1988 to 21 in There was a peak in the number of workers in 1989 (n = 4,995), with the lowest number in 1999 (n = 2,669) Number of workers 0 1,000 2,000 3,000 4,000 Supervising Other exposed worker Stripping/encapsulating Number of examinations = 53,529 Figure 9 Number of removal workers in each job type by year of examination,

27 Number of workers 0 1,000 2,000 3,000 4,000 None Half face Air stream Minimal Full face Positive pressure Number of examinations = 55,050 Figure 10 Number of removal workers using the different types of respirator by year of examination,

28 Table 11 Length of time (hours) removal workers spent stripping each week by year of examination, Year of examination Mean sd Median Minimum 25 th percentile 75 th percentile Maximum Number of workers , , , , , , , , , , , , , , , , ,248 20

29 Number of workers Hours per week Number of workers Hours per week Figure 11 The number of removal workers and the mean number of hours spent stripping per week, by year of examination,

30 3.4 MANUFACTURING WORKERS The graphs and tables in this section present the data for manufacturing workers under the CAWR period. Table 12 shows the age of manufacturing workers by sex. The majority of workers in manufacturing were men (91%) and came for their first examination between the ages 20 and 49 (74%). Only 261 women described themselves as working in manufacturing (9%). The overall average age was 43 years (sd 12 years). Most women had their first examination between the ages 20 and 49 (74%). The number of workers in manufacturing declined steadily between 1988 and 2004 (see Figure 12) from 1,589 in 1988 to 58 in Of the seven different sectors within manufacturing, the largest proportion of workers (63% overall) was employed in the manufacture of asbestos/rubber/resin/bitumen mixtures and this pattern was consistent throughout the period. Between 1988 and 1996, workers employed in the manufacture of textile undertook 971 medical examinations after which there were no medical examinations recorded in textile manufacturing. The proportion of maintenance workers in all manufacturing sectors increased steadily from 16% in 1988 to 53% in Few reported working in the remaining sectors (manufacture of asbestos cement mixture, asbestos board and paper, garment manufacture or the manufacture of dry mixes for insulation and plastering ). Table 13 shows the mean number of hours that manufacturing workers spent each week in a respirator zone for each year of examination between 1988 and There was an overall decline in the mean number of hours within this period (9.1 hours in 1988 to 0.50 hours in 2004), although the maximum number of hours worked ranged between 8 and 83 hours). The average number of hours spent in a respirator zone fluctuated over the period, with peaks in 1988 (9.1 hours), 1994 (7.3 hours), 1999 (6.2 hours) and in 2002 (7.8 hours). The mean for the whole period was 6.1 hours (sd 13). The median time spent in a respirator zone was zero hours for all years except 2002, when the median was 1 hour (maximum 83 hours). The mean number of hours manufacturing workers spent per week in an asbestos area by examination year is reported in Table 14. The mean number of hours for the whole period is 25 hours (sd 18 hours). The median was 35 hours, and the maximum ranged between 40 and 90 hours. This was a bimodal distribution, with high frequencies (12%) in the classes 0-2 hours and hours. The mean number of hours varied little during this period (range 21 hours to 34 hours), except for in 1998 and 2004, when the mean number of hours was only 6.6 and 5.0 hours respectively. 22

31 Table 12 Manufacturing workers: age at the first medical examination by sex, Age (years) at first examination Women Men Total <20 14 (18, 5) 61 (82, 2) 75 (100, 3) (12, 16) 280 (88, 11) 319 (100, 12) (7, 11) 356 (93, 14) 385 (100, 14) (9, 12) 347 (91, 14) 383 (100, 14) (8, 9) 309 (92, 12) 331 (100, 12) (10, 13) 279 (90, 12) 312 (100, 12) (10, 13) 263 (90, 11) 292 (100, 11) (8, 12) 262 (92, 10) 285 (100, 10) (8, 7) 233 (92, 9) 249 (100, 9) 60-4 (4, 2) 139 (136, 5) 143 (100, 5) Total 245 (9, 100) 2529 (91, 100) 2774 (100, 100) Data are counts with row and column percentages in parentheses Number of workers ,000 1,500 Textile Cement Board DryMixes Garment Mixtures Maintenance Number of examinations = 7,851 Figure 12 Number of workers in the manufacturing sectors by year,

32 Table 13 Length of time (hours) manufacturing workers spent each week in a respirator zone by year of examination, Year of examination Mean sd Median Minimum 25 th percentile 75 th percentile Maximum Number of workers , ,

33 Table 14 Length of time (hours) manufacturing workers spent each week in an asbestos area by year of examination, Year of examination Mean sd Median Minimum 25 th percentile 75 th percentile Maximum Number of workers , ,

34 3.5 OTHER WORKERS The tables and graphs in this section present the data for Other workers under the CAWR period. There were three industry sectors included in Other workers: shipbuilding, repair and breaking; building and construction; and miscellaneous processes. Miscellaneous processes covered use of asbestos string/rope/felt; fitting clutch and brake pads; machining/cutting asbestos board; and other exposed workers. The age and sex of workers who categorised their job as something other than manufacturing, or stripping and removal are reported in Table 15. The overall mean age at the first medical examination was 39 years (sd 11 years). Most women had their first medical examination between 20 and 34 years, with very few women having their first medical examination after turning 50 years (mean 30 years and sd 9.0 years). Most men had their first examination between the ages 20 and 49 years (mean 38 years and sd 11 years). Table 15 Other workers: age at the first medical examination by sex, Age (years) at first examination Women Men Total <20 6 (6, 3) 100 (94, 2) 106 (100, 2) (8, 24) 624 (92, 11) 681 (100, 11) (7, 31) 857 (93, 15) 927 (100, 15) (4, 18) 921 (96, 16) 957 (100, 16) (3, 9) 845 (97, 14) 866 (100, 14) (2, 6) 791 (98, 14) 807 (100, 13) (2, 5) 626 (98, 11) 636 (100, 11) 50-4 (1, 1) 527 (99, 7) 531 (100, 8) 55-3 (1, 1) 382 (99, 6) 385 (100, 6) 60-3 (1, 2) 224 (99, 4) 227 (100, 4) Total 226 (4, 100) 5,897 (96, 100) 6,123 (100, 100) Data are counts with row and column percentages in parentheses Figure 13 displays the percentage of workers in other industry sectors by year of examination (1988 to 2004). Overall, the majority of workers were in the building and construction sector until 1997 (range 67% to 91%). In 1998, the percentage in this sector dropped to 43% and fell to 22% by In 1999, the number of Other workers nearly trebled. The percentage in miscellaneous work increased from less than 1% before 1999, to 22% in 1999 and 60% in The percentage of workers in shipbuilding varied between 9% and 40% in this period. The percentage of Other asbestos workers using different types of protective respiratory methods is presented in Figure 14. Between 1988 and 2004, the types of respiratory protection varied by year. The most commonly used methods overall were the half-face mask (mean 31%), followed by minimal protection (mean 19%) and no protection (mean 17%). Few used a positive pressure mask/blouse (mean 12%) or air-stream helmet (mean 13%). Only a very small proportion of workers used the full-face mask (8%). The most common method between 2000 and 2004 was the half-face mask. The proportion of those who used no protection was at its peak between 1994 and 1997, but 26

35 then dropped to around its mean level of 17%. In 2004, 77 workers were not using any facemask or other method of protection against breathing asbestos Number of workers Shipbuilding Miscellaneous Building Number of examinations = 5,093 Figure 13 Number of workers in Other industry sectors by year of examination,