Pneumoconiosis measured at exposure: Prevalence of small Medical the static dust M=16 years irregular opacities sampling graded 1/0 or more = 82=crepitation’s locations in 21.2% pleural changes the area = 7%. 4/36 subjects Smoking history where the job with exposures < 50 available was carried fibre/mL-year had out. signs of asbestosis. Fibre counts Author’s conclusion: were not For possible and available for certified asbestosis the 1951-60, but 1% prevalence’s Thermal estimated at 55 and 72 Precipitator fibre/mL-year particle counts respectively. The most were available reliable data relate to for 1952 and men first employed 1960. after 1950 the average The fibre cumulative exposure counts for was 84 fibre/mL-year, 1951-1955 the average follow-up were taken as since first exposure those of 1961 was 16 years, and the multiplied by prevalence of possible the ratio of the asbestosis was 6.6 %. 1952 to the Higher prevalence of 1960 thermal crepitation’s at any precipitator dose than previously measurement. observed. No room for complacency The counts for regarding the 2 1956-1960 fibre/cm3 standard of were taken to the British be the same Occupational Hygiene as 1961-1965. Society. Before 1950
Pneumoconiosis Medical 82=crepitation’s Smoking history available measured at the static dust sampling locations in the area where the job was carried out. Fibre counts were not available for 1951-60, but Thermal Precipitator particle counts were available for 1952 and 1960. The fibre counts for 1951-1955 were taken as those of 1961 multiplied by the ratio of the 1952 to the 1960 thermal precipitator measurement. The counts for 1956-1960 were taken to be the same as 1961-1965. Before 1950 exposure: M=16 years Prevalence of small irregular opacities graded 1/0 or more = 21.2% pleural changes = 7%. 4/36 subjects with exposures < 50 fibre/mL-year had signs of asbestosis. Author’s conclusion: For possible and certified asbestosis the 1% prevalence’s estimated at 55 and 72 fibre/mL-year respectively. The most reliable data relate to men first employed after 1950 the average cumulative exposure was 84 fibre/mL-year, the average follow-up since first exposure was 16 years, and the prevalence of possible asbestosis was 6.6 %. Higher prevalence of crepitation’s at any dose than previously observed. No room for complacency regarding the 2 fibre/cm3 standard of the British Occupational Hygiene Society.