Development of a methodology to measure dust emissions of electric handheld woodworking machines

Outline of reasons and objectives
In France, wood dust is classified on the national list of carcinogenic processes and the decree of 23 December 2003 sets a stringent occupational exposure limit value for wood dust of 1 mg.m-3 that has been applicable since 1st July 2005. On average, over 120 cases of occupational diseases related to wood dust, including 70-80 cancers are recorded every year by the general health insurance scheme. The objective of this study is to put in place a methodology for characterising emissions of wood dust from electric handheld machinery. Such machinery is in widespread use in the woodworking industry and it has particularly high levels of emissions.

Approach
A test method was chosen on the basis of the existing European Standard EN1093-3 and was applied to electric handheld woodworking machines. For that purpose, a ventilated booth was used during the work. The tests were made via a robot so as to optimise the repeatability of the measurements and so as to avoid subjecting an operative to exposure. Various sensors were selected to measure the concentration of dust emitted during the tests. Specific machining cycles were determined for assessing five sanders and nine circular saws. The work focused mainly on characterising emissions from random orbit sanders and from circular saws. The head-loss related to the extractor network for extracting the dust and to the various machines was measured in order to determine the relative fan power and the suction flow rates for each machine.

Main results
The results of this method made it possible to establish a level of concentration of dust emitted by the sanders and circular saws that were tested. These measurements showed the possibility of developing a classification for the machines.
A statistical analysis was conducted and made it possible to confirm the distinctions made between the machines. For sanders, one machine emitted more dust than the others. As regards the circular saws, we can conclude that three of the nine machines had lower concentration values (factor of 7 between the most emissive and the least emissive).

Discussion
This study made it possible to put in place a test procedure for characterising the emissions of woodworking machines.
It can be used for studying other machines and other types of particulate pollutant. The manufacturers and designers of machines, and also the professional associations can appropriate it and use it to establish a criterion for choosing between various machines as regards dust emission. In parallel with this study, standardisation work is in progress through CENELEC with a view to publishing dust measurement methods with the manufacturers of handheld machinery. Furthermore, in 2016, a new version of the machinery directive is to be discussed. Adding information about dust emission would be useful for prevention. An indication regarding the emission of a machine would enable company managers and users to steer their choices towards equipment having the lowest levels of emissions.