Sources and health implications
Generally timber present no health hazards in itself. On the other hand, inhalable particulate size may possess toxic, immunological and carcinogenic properties (11). Respirable dust of any kind can irritate the respiratory system or interfere with mucociliary action; a number of woods are irritants of the skin (e.g. iroko, keruig, afromosia), the respiratory track (e.g., beech, iroko, maple) or the eyes (e.g. yew, tak, satinwood). Some such western red cedar, iroko and mahogany, cause allergic asthma. Other woods are poisonous (e.g. yew and oleander) such that can cause nausea and malaise and affect the heart (49). According to IARC, wood dust is carcinogenic to humans (28). Woods directly implicated are beech, oak, and redwood (49). Furthermore, large quantities of airborne wood dust in an enclosed spare can cause an explosion, and some wood dust will spontaneously combust on contact with certain oils or chemicals.
Factors influencing exposure
People most at risk are those exposed to high levels of dust during the sanding and machining processes during production. Though construction workers are less exposed to wood dust hazards compared to carpenters, joiners and factory workers, on site fitting with equipment that lacks the dust retention features available in factories may present a hazard. On site sanding processes also offers opportunities for heavy dust exposure (11).
Acceptable exposure levels
In UK, all hard wood dusts have a Maximum Exposure Limit (MEL) of 5 mg/m3, however this is considered to be totally inadequate as the mucociliary escalator, the throats’ natural defence is severely impaired at 2 mg/m3. Dust levels must therefore be kept as low as possible (49).
Protection of employees in the workplace is of a high priority mitigation measure. The work system must control dust from wood to ensure dust levels are below the MEL. Housekeeping methods must keep workshops free from dust, and dust must be disposed of safely. In a factory or joinery shop, permanent mechanical ventilation should be installed. On a construction site or temporary workplace, cutting in the open air will reduce dust problems but not solve them. Portable dust extractors could be of much assistance. Respiratory protective equipment should also be used.
All types of wood which have been proved carcinogenic should be substituted with safe species.
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