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Industrial wood flake drying generates methanol, formaldehyde, and other hazardous air pollutants (HAPs). A simple theoretical model shows that particles smaller than 400 microm will begin to thermally degrade and release disproportionately large quantities of HAPs. This is confirmed in full-scale practice where particles smaller than 500 microm show visible signs of charring. Laboratory measurement of the activation energy for the breakdown of wood tissue into methanol and formaldehyde led to a value of about 17 kcal/mol. The apparent activation energy measured in the field was higher. This result was obtained under nonisothermal conditions and is biased high by the fines fraction of the furnish, which is exposed to elevated temperatures. It is proposed that a combination of screening out the fines fraction smaller than 500 microm and reducing the dryer inlet temperature will substantially reduce emissions, possibly to the point where control devices can be downsized or eliminated. Our findings allow these HAPs reductions to be semiquantitatively estimated.

In Britain, the law places duties on employers and suppliers to provide information to ensure health and safety of employees, so far as is reasonably practicable, and there are regulations for the appointment of employees' safety representatives which employers are required to consult. A recent survey by HSE has shown that suppliers are the most important source of information on substances. However, the flow of information is often obstructed by barriers between the suppliers and the companies, and within organisations. Safety representatives, where they exist, are often better informed than employers, and in companies with safety representatives accident rates are lower. Information from suppliers can be inappropriate for the end use, and the goal-setting approach which has dominated in recent years may not help the non-expert employer. We welcome HSE's move to more specific control guidance for chemicals.