In the wood products industry, wood dust is regulated for both its potential combustibility as well as for exposures that could affect human health risk. While the content of the rulemakings would look very different, there are key elements that should be integrated into either rule:
- Wood dust regulations should primarily rely on performance-based approaches rather than prescriptive specification standards.
- Existing facilities should be permitted to use alternatives to expensive engineering retrofits - such as administrative or housekeeping measures - to reduce the risk of dust-related concerns in a cost-effective manner.
Any combustible material in a finely divided form, such as dust, can burn rapidly. If dust is suspended in air at the right concentration, under certain conditions it can become explosive. Even materials thought to be non-combustible that do not burn in larger form (such as aluminum or iron) can be explosive as dusts given the proper conditions. Unique concerns for a combustible dust rule are as follows:
- In response to an AWC request, OSHA has instructed its inspectors to consider the bulk densities of light dusts (less than 75 lb/ft3) when determining whether a hazard exists;
- Wood dust with a moisture content of 25 percent or more and/or particle sizes of 500 microns or larger should not be viewed as an explosive dust; and
- Explosivity testing should be conducted under real world conditions rather than assuming worst case scenarios, such as by grinding of dust particles into smaller sizes.
- OSHA should consider all studies as part of a Weight of the Evidence evaluation of wood dust exposures to inform the proper classification and Permissible Exposure Limit (PEL) for wood dust.
- Currently there is not an OSHA substance-specific standard for wood dust. Establishing an appropriate PEL is one important step in ensuring the health protection of exposed workers.