The HSE have designated both hardwood and softwoods as asthmagens and hardwoods as a carcinogen.
Wood is classified into two broad families, hardwood and softwood. The classification is botanical and depends on the fine structure of the cells in the wood species. It does not refer to the physical properties of the wood, e.g. balsa wood is a hardwood!
Hardwood has a workplace exposure limit (WEL) of 3mg/m3 8-hour TWA, and softwood 5mg/m3
The lower limit applies for mixed woods.
Inhalation of fine dust can have many effects on the respiratory tract, including:
- Rhinitis (Runny nose)
- Violent sneezing
- Blocked nose
- Nose bleeds
- Very rarely – nasal cancer (a recognised industrial disease associated with the inhalation of hardwood dusts)
The most common effects arise from irritation, where symptoms usually only persist as long as the sufferer remains in contact with the irritant. Allergic effects, because of sensitisation to wood dust can also occur. Some examples of this are:
- Rhinitis
- Asthma
- Impairment of lung function
- Rarely – extrinsic allergic alveolitis (a disease with ‘flu-like’ symptoms which can cause progressive lung damage) e.g. when using western red cedar, iroko.
Asthma is of particular concern. Most wood dusts can irritate the respiratory tract provoking asthma attacks in sufferers, although effective control of dust levels normally improves the problem.
Some wood dusts can cause asthma as a specific allergic reaction. Once sensitised, the body will quickly react if subsequently exposed, even to tiny traces of dust. Unlike irritation, where people can continue to work with the dust once it is controlled to below the level at which irritation occurs, people who become sensitised will not normally be able to continue working with the dust, no matter how low the exposure. Some of the effects on the eyes include:
- Soreness
- Watering
- Conjunctivitis
Wood dust also has the potential to cause harm through explosion or fire. Wood dust is explosive if ignition of part of a cloud of wood dust results in the propagation of flame through the rest of the cloud. You should assume that all wood waste is potentially explosive, unless a dust explosion test demonstrates it is not.
HSE document WIS32 “Safe collection of wood waste: Prevention of fire & explosion” provides some very good advice on this subject. You must ensure that you comply with DSEAR Regulations, and this may involve engaging with a specialist consultant.
Visit our wood dust solutions page here.