Exposure to wood dust among carpenters in the construction industry in The Netherlands

Exposure to wood dust was measured among 26 carpenters at 13 building projects. Sampling days were chosen randomly. Individual tasks, based on technology applied and material used duringaworkingday,weresampledseparately.Fromthesetask-basedmeasurements,8htimeweighted average concentrations were calculated. Sampling was performed in accordance with a protocol that was developed by the carpentry and furniture industry and which was especially designed for sampling of wood dust. Eight hours time-weighted average exposure to wood dust ranged from 0.8 to 11.6 mg m 3 with a geometric mean (GM) of 3.3 mg m 3 and a geometric standard deviation (GSD) of 2.1. The probability of exceedance of the OEL, when comparing the estimated concentrations against the Dutch OEL of 2 mg m 3 , was 75%. The highest exposures were measured during sawing of Cempanel sheets. Task-based measurements showed lowest exposures when working outdoors (n = 11, AM = 2.2 mg m 3 ), but even then 5 out of 11 task-based exposures exceeded 2 mg m 3 . Indoors the exposure was 5.2 mg m 3 (AM, n = 29) and when working both indoors and outdoors exposure was 16.2 mg m 3 (AM, n = 4). In conclusion, long-term average exposure to wood dust among carpenters at construction sites is more than 1.5 times the present occupational exposure limit of 2 mg m 3 . The estimated probability of exceedance of the OEL was 75% and a reduction of exposure with a factor 5 is needed to bring the probability of exceedance below 5%. It is intended to lower the exposure limit to 1 mg m 3 by 1 January 2007. In that case the probability of exceedance of the OEL is 95% and a reduction of exposure with a factor 10 is needed to bring the probability of exceedance below 5%. This can be achieved by using alternative materials, preparation of building material in workshops equipped with exposure controls, alternative equipment and improved ventilation and good housekeeping.