Wood dust in schools

Schools typically contain a wide variety of woodworking machinery ranging from high volume dust producing equipment e.g. circular saws, planer thicknessers to low volume dust producing equipment e.g. fret saws, mortisers.

In addition to the wood dust produced by machinery, significant amounts of dust can also be released into the air during cleaning and when changing filters on dust extraction equipment.

The risks of exposure to wood dust are well documented and a recent prosecution of a Scottish Council and subsequent fine for a number of breaches of the COSHH 2002 regulations which led to a teacher developing occupational asthma demonstrates the need to adequately assess and control the risks to staff and pupils from wood dust.

Requirements for control of wood dust

The requirements for the control of wood dust are set out in the COSHH 2002 regulations and HSG 258 guidance.  Further information is also set out in a variety of woodworking information sheets and the wood dust page on the HSE wood working website at www.hse.gov.uk/woodworking/wooddust.htm

The key points are as follows:

• Both hardwood and softwood dusts have a Workplace Exposure Limit (WEL) of 5mg/m3 which must not be exceeded. These are limits placed on the amount of dust in the air, averaged over an eight-hour working day. However, you must reduce exposure to wood dust to as low as ‘reasonably practicable’.
• Never sweep up or use compressed air lines as this will disturb the dust and allow it to become inhaled. Always clean up using a suitable vacuum cleaner with HEPA filters, or a vacuum attached to the extraction system.

Current practice in schools

A typical school may contain a large ducted system in the Technician’s preparation room and a number of small ‘stand alone’ extractors within the classrooms.  In addition vacuum cleaners may be provided within classrooms for the cleaning of floors and benches however, in practice, brushes are often still used for cleaning.

The drawbacks of such arrangements can be as follows:

• Units are often poorly maintained e.g. manual shaker units are not operated and filters quickly become blocked, reducing performance and passing fine dust back into the classroom.
• Multiple dust collection bins/trays or bags require to be emptied, a process which can produce high levels of exposure to the operator.
• The use of multiple extractors in classrooms can create high noise levels.
• Unless the units are interlocked to the wood working equipment then the extraction is often not used.
• The cost of replacement filters for multiple units can be very high
• There is often no provision for extraction from portable tools e.g. sanders

Other arrangements sometimes found in schools are traditional low velocity/low pressure systems which have been ducted out to classrooms.  These are typically fitted with manual sliding dampers to control flow rates to individual machinery.  The key drawback of such systems is that system dampers are often left open when not in use meaning that the flow rate to other areas of the system is reduced and/or dampers are not opened when the machines are used.  In addition the system needs to be running constantly to ensure that extraction is available when required.