Respiratory protection for woodworking

Wood dusts and other contaminants are produced in various tasks commonly carried out both in the workplace and in the home/hobby situation. These materials, if present in high enough levels, are a respiratory hazard and suitable precautions should be taken.

In 1995, the International Agency for Research on Cancer (IARC) designated wood dust as a known human carcinogen (Group 1). This was on the basis of the confirmation of the correlation between inhalation of wood dust and a rare type of adenocarcinoma involving the nasal sinuses.

Hardwood and exotic woods, rather than softwood, are the most likely candidates for inducing this cancerous effect. Certain types of hardwoods (eg, beech, oak) are potentially a source of more severe outcomes.

Research has found that there is evidence of an increased incidence of nasal cancers in chronic exposure areas like the furniture and cabinet-making industries and a similar outcome is suspected in sawmilling, carpentry and joinery, and in the paper and pulp industry. This type of cancer has a latency period of around 40 years. However, cases have been reported as little as five years after exposure. This makes the use of exposure controls and suitable respiratory protection essential where overexposure to wood dusts occurs routinely.

The most common effect from overexposure to wood dust is irritation of the respiratory tract, starting from the nose and reaching down into the throat. The dust in these areas can cause coughing, irritation and hoarseness.

Respiratory and dermal hypersensitivity in woodworkers has also been observed resulting in asthma, rhinitis and dermatitis. The complex chemical compounds in wood are thought to be responsible for these allergic reactions.

Symptoms of overexposure may include:

• coughing, sneezing, breathing problems
• nose bleeding, vomiting, nausea
• headache, giddiness, vision disturbance

Potential exposure processes:

• sawing, milling, planing
• chipping, sanding, routing
• shaping,  thicknessing, tenoning
• moulding, jointing, turning

The wood that has been most studied is Western Red Cedar. Researchers in British Columbia have identified asthmatic responses provoked by inhalation of plicatic acid, a water-soluble component in Western Red Cedar. In Australia, Safe Work Australia has set exposure standards for certain hardwoods at 1 mg/m³ and for softwoods at 5 mg/m³ as the 8 h average concentrations, which should not cause discomfort or adverse effects in nearly all workers. Note that sensitised individuals may have reactions to much lower levels. The American Conference of Governmental Industrial Hygienists (ACGIH) has recommended an exposure standard of 0.5 mg/m³ for Western Red Cedar in TLV publication for several years.

Solutions

Preventative measures such as extract ventilation, filtered air and water sprays can help control dust exposures. However, where these are not available or not practicable, use of respiratory protection is indicated. This will be the case in the majority of situations encountered during common woodworking tasks.

For exposures to levels up to 10 times the exposure standard, the respirators are available that will provide suitable protection. 3M has available the following suitable respirators: valved flat fold respirator 9312 P1; flat fold respirator 9310 P1; valved cupped respirator 8812 P1; cupped respirator 8710 P1. These products used and fitted correctly will provide protection against wood dust up to 10 times the exposure standard.

Higher concentrations of dusts will require respiratory devices with higher protection levels such as full face respirators or powered air purifying respirators like the 3M Jupiter with the M-106 headtop.

Lead paints

Working with recycled painted wood has hazards related to the possible presence of lead in the paint. High levels of lead can be released during stripping or sanding operations, either into the lungs or as particles swallowed into the stomach. High lead intake can cause long-term health problems. For heat stripping of the lead paint, there can be amounts of lead fume released.

Respirators suitable for sanding tasks available from 3M include: valved flat fold respirator 9312 P1; flat fold respirator 9310 P1; valved cupped respirator 8812 P1; cupped respirator 8710 P1.

Respirators suitable for heat stripping of lead paint include 3M’s valved flat fold respirator 9322 P2; flat fold respirator 9320 P2; valved cupped respirator 8822 P2; cupped respirator 8210 P2.

MDF and formaldehyde

Use of MDF (medium density fibreboard) raises the added possibility of exposure to formaldehyde vapours - this is used in the bonding process during manufacture of MDF. As well as wood dust, formaldehyde can be released during cutting or milling of the MDF product.
Eye and upper airway irritation are common symptoms from overexposure to formaldehyde while using MDF. Formaldehyde has been designated a sensitiser that can cause a specific immune response in some people. Exposure to a sensitiser, once sensitisation occurs, may manifest itself as a skin rash or inflammation or as an asthmatic condition, and in some individuals this reaction can be extremely severe.

Formaldehyde is also designated by IARC as a Group 1 carcinogen and exposures should be kept as low as possible by well-maintained ventilation systems. Where these measures are insufficient, other means of control are required, PPE being one such approach.

Specific respiratory protection solutions for formaldehyde that meet the performance requirements of Australian Standard 1716 are available from 3M. These include: premium half face respirator 7500 series (7501 small, 7502 medium, 7503 large) and standard half face respirator 6000 series (6100 small, 6200 medium, 6300 large). The 7500 and 6000 series respirators need to be fitted with the company’s organic vapour and formaldehyde filter 6075 or organic vapour/acid gas filter 6057. The filter, fitted with the company’s particulate filter 5925 P2 and particulate filter retainer 501, will provide combined protection against formaldehyde and wood dust up to 10 times the exposure standard for a trained, fitted, clean-shaven wearer.