In enforcing the dust-free working regulations, the Inspectorate SZW – the Dutch labour inspectorate – checks for what it calls “visible dust” in the so-called “employee inhalation zone”, caused by various different activities: drilling, chipping, grinding, sawing and so on. If dust is found in this zone, that indicates either that the proper controls are not in place or that they are not being applied correctly. In both cases, corrective action must be taken. Otherwise, the inspectorate may suspend work and/or impose fines.
Employers are also required to show that the their work is being conducted in healthy manner. This could be done by measuring exposure in the workplace, but in practice that is very difficult and expensive. For this reason the inspectorate also recognises and accepts the use of validated tool systems – that is, proven combinations of tools, an extraction unit, a vacuum extractor and other controls.
The TNO Performance Test is one example of an approved validation process, but other independent testing procedures by reputable institutes are also accepted. The inspectorate expresses no opinion about individual system components (extractors, filters, etc.); the sole determining factor in its inspections is overall exposure to a harmful substance, as measured in the employee inhalation zone.
See also the Inspectorate SZW website.
The technological “state of the art” for dust-free tools is determined largely by a combination of the following factors.
The most effective way to prevent dust entering the employee inhalation zone is to enclose its source (the drill, sander, grinder, etc.) as effectively as possible. The better this is done, the fewer demands are made of the extractor and other controls. Compared with other techniques, such as water suppression and misting, a vacuum extractor system is the most efficient way of curtailing the spread of dust. The more “open” the source is, the greater the suction power required of the extractor. The quality of the filters (H, M and L) is also important, in part determining the degree of secondary dust release in the working area. Another significant parameter is the nature of the filter cleaning system: whether it is automatic or manual, vibrating or pneumatic.
It is the combination of all these factors which ultimately determines the overall quality of the tool system, and hence how much dust the worker using it is exposed to.