Information sheet: Softwood Dust Workplace Exposure Standard
In December 2010, the Department of Labour lowered the Workplace Exposure Standard (WES) for softwood dust.
The previous WES for softwood dust was:
- 5mg/m3 TWA (Time Weighted Average)
The new WES for softwood dust (effective from December 2010) is:
- 2mg/m3 TWA for both eight-hour and 12 hour shifts.
- The previous short term exposure limit (STEL) of 10mg/m3 is withdrawn.
The new WES will be implemented over a two-year period, commencing 13th December 2010. This means that employers have two years to make any changes necessary to meet the new WES.
What is a Workplace Exposure Standard?
There are, in fact, a number of Workplace Exposure Standards (WES), designed for exposures over various time periods. In assigning the WES, defining a level that will achieve freedom from adverse effects is the major consideration.
In the case of softwood dust, we use the following value:
- Time Weighted Average (TWA) – this means an average exposure of up to 2mg/m3 (milligrams per cubic metre) of softwood dust over the course of an eight-hour or 12-hour work day is permissable without experiencing poor health effects.
How are WES used in the workplace?
WES are used in relation to monitoring hazardous substances in the workplace environment. Special monitoring equipment is needed to measure airborne substances in the workplace (called air sampling). The equipment can cost a lot of money, and you need specialist training in how to take representative samples and make a correct analysis. In most workplaces, air sampling is carried out by occupational hygienists or people with similar qualifications and experience.
In all instances WES relate to exposure that has been measured by personal monitoring using methods that gather air samples from the workers’ breathing zones. The objective of personal monitoring is to assess the air a worker is breathing, as it is the workers’ exposure that the WES is concerned with.
Section 11 of the Health and Safety in Employment Act 1992 requires employers to provide the monitoring results to the workers concerned.
Why did the Department of Labour change the WES for softwood dust?
The softwood dust WES was lowered because current research shows that adverse health effects of softwood dust can occur at concentrations lower than previously thought.
Lowering the WES value means more may have to be done in the workplace to reduce the level of worker exposure to this substance.
What are the health effects of softwood dust exposure?
The effects of exposure to softwood dust include upper respiratory tract irritation such as a cough, nasal irritation, eye irritation, blocked or runny nose, sinus infections and long-lasting colds. Other effects may include changes to the cell lining of the nose and other respiratory mucosa, and a decrease in the ability to clear fluid from the upper respiratory tract.
Adverse effects may also be found in the lower respiratory tract, including impaired lung function, occupational asthma, bronchitis, scarring of the lung tissue, and other allergic respiratory problems.
Some wood dusts are carcinogenic to humans. Certain types of hardwood such as beech and oak are associated with cancers of the nose and respiratory tract. However, softwood dust also poses potential for cancer development.
In some industries, workers are exposed to both hardwood and softwood dusts, making the lines of distinction between the health effects of hard-and softwood dust more blurred.
What occupations are linked to softwood dust exposure?
People are usually exposed to softwood dust in the following industries:
- furniture and other wood manufacturing
- joineries
- carpentry
- wood processing, including sawmills, veneer and plywood plants, woodchip operations.
What can be done to lower the amount of hazardous substances in the workplace air?
There are a number of ways to lower contaminants in the air, but it depends on a number of factors including the work process, the equipment used and the environment you work in.
Here are some general examples of what could be done to lower worker exposure to hazardous substances:
- where practicable, replace old machinery using poor extraction ventilation with new machinery capable of efficient dust capture and extraction;
- install local extraction ventilation to take the air containing the contaminant away from the workers;
- enclose manufacturing processes so that all of the work involving the contaminant is conducted in a separate room or chamber that no-one normally works in;
- ensure that good housekeeping practices reduce the build-up of dust inside machinery and work areas;
- use vacuum methods to collect excess dust instead of brooms and air-jet hoses; and
- ONLY as a last resort or as an interim measure while long-term solutions are introduced: use personal protective clothing and equipment (PPE) to further reduce worker exposure.
Why can’t we just rely on PPE to protect us from harm?
The Health and Safety in Employment Act 1992 places duties on employers to eliminate all significant hazards in the workplace to ensure the safest working environment.
But in a lot of cases, we need to work with certain machines, chemicals and hazardous processes in order to get the job done. If the hazards cannot be eliminated, the employer is required to isolate the hazards from the workers.
Eliminating and isolating hazards can be initially expensive, and can take some time to develop. But they are the preferred method of hazard management, and make good business sense in the long term.
If some hazards cannot be eliminated or isolated, the employer must minimise employee exposure. Minimisation may include extraction ventilation, job rotation and using PPE.
PPE may seem like the cheapest way to solve a hazardous substance exposure problem, but in most cases, it may end up costing the employer more money, and may place the worker at risk.
Common respiratory protection does not provide 100% protection against the substance.
Other issues with relying upon PPE as the sole means of safety management include:
- poorly maintained PPE (e.g. holes in gloves, unchanged mask filters) increases worker exposure;
- workers sometimes forget to wear the PPE;
- workers may find it uncomfortable to wear the PPE and may take the risk of removing it in a hazardous work environment;
- consumable PPE can cost a lot of money to replace;
- the PPE may not provide protection against a large surge of a contaminant in the event of an accident;
- the workplace environment has to be regularly monitored to check that hazardous substances are still within safe levels; and
- workers may have to undergo monitoring (lung function tests) to assess their exposure to wood dust even though they are using PPE.
In your workplace, the principles for dealing with airborne substance exposure must be to:
ELIMINATE, ISOLATE, MINIMISE.
Further sources of information:
- Workplace Exposure Standards effective from 2010
- The Approved Code of Practice for the Management of Substances Hazardous to Health in a Place of Work
