Air Quality Control

slider dust extraction

Air Quality Control – Case Study

…an update for those in the joinery, kitchen and cabinetmaking industries

The issue of air quality in modern factories that manufacture joinery, cabinetry, kitchen componentry or wooden furniture componentry has always been a bit like the elephant in the room: everybody knew about it but not much seemed to be done to deal with it. The process of substantive change got a kick along with the introduction of CNC technology in the early nineties and an increasing awareness of the dangers such airborne hazards posed for those working in these factories and the enforcement of the relevant legislation. The installation of new extraction systems and the renovation of older ones became de rigeur from the early 1990’s onwards. These systems were technologically superior being more powerful and efficient than previously. The case for improving work place conditions so they meet the legal requirements for a healthy and safe working environment has not gone away either. JOINERS Magazine spoke with the Ministry of Business, Innovation & Employment (MBIE) who through their Health & Safety Group, administer the relevant legislation and regulations that govern amongst other things the broad issues of ventilation and dust extraction and got an update: what the current requirements are and the continuing need for employers to adhere to the various health and safety requirements involved. Much of the following information is based on what MBIE have supplied.

In looking at the issue the interesting thing is that there is no specific legislative requirement with regard to dust extraction except indirectly as a practicable step as under Section 10 (2)a and b of the Health & Safety In Employment Act (HSE) of 1992 which says under (2)a an employer must take all practicable steps to minimize the likelihood that the hazard will be a cause of harm to employees and under (2)b to provide, make accessible to, and ensure the use by the employees of suitable clothing and equipment to protect them from any harm that may be caused or any that arise out of the hazard. Wood dust is not an approved substance under the Hazardous Substances and New Organisms Act (HSNO) of 1996 either so the HSNO regulations do not apply. Wood dust is covered though under the HSE Regulations of 1995 that run along aside the HSE Act, under the General Duties of Employers. Under section 4(2) (i) the employer must have the “facilities to enable any atmospheric contaminants to be controlled as closely as possible to their source” and Section (4) (j) the “facilities for treating or carrying off any atmospheric contaminants for the purpose of minimizing the likelihood that any atmospheric contaminants will be the cause or source of harm to any employer.”

The bottom line is that these two definitions could refer to extraction ventilation in a range of situations including a factory situation where wood dust is created. The Regulations are really saying that an employer is required to take All Practicable Steps (APS) to ensure these facilities are provided and are suitable for the purpose; there are sufficient numbers of them; they are in good order and convenient to employees. By inference, this means for those operating joinery and cabinetmaking operations involving solid wood and MDF that they need to have adequate extraction ventilation. For those involved in specific substances such as asbestos or spray coating there are specific regulations that may refer to extraction ventilation.



The Need To Protect

The rationale behind having dust extraction ventilation is simple: to protect people’s health and to protect the product. A third reason is somewhat understated: to prevent dust build up and the risk of dust explosions. As MBIE says, all three reasons may be relevant or any combination of them. Interestingly, there is a Code of Practice for Handling Combustible Dusts (AS/NZS 4745: 2012) and although wood dust is not specifically mentioned, it is regarded as potentially explosive. The key is the amount of wood dust an employee may be exposed to in a factory situation. To cover this there is something called Workplace Exposure Standards (WES). Unfortunately WES are not referenced in the HSE Act 1992 (the exception is in the Asbestos regulations and only for the asbestos Workplace Exposure Standard) so there is no Health and Safety legislative mention of specifically wood dust; however, neither is there of the hundreds of thousands of other chemicals, and other hazards that may occur in the workplaces. Workplace Exposure Standards are mentioned and enforceable under the HSNO Act 1996 but wood dust does not come under this Act either.

The Building Code

Wood dust is in effect covered by the Building Act which refers to the Building Regulations. These Regulations contain the Building Code which say that ‘the acceptability of indoor air purity for workplaces may (although this does not mean ‘must’) be verified by demonstrating that contaminant levels do not exceed the Workplace Exposure Standards. In effect then, under the Building Act a company could show that the WES were not being exceeded when the extraction ventilation was being used. It is interesting to note that the Building Regulations 1992 refer to the need for buildings to have the means of collecting or otherwise removing amongst other things ‘airborne particles’ (Building Regulations 1992 G4.3.3 (g)). Air purity levels are key to the modern joinery, cabinetmaking, furniture making and kitchen manufacturing operations.

Workplace Exposure Standards (WES) Changes

Workplace Exposure standards (WES) are the mechanism by which the level of air purity is judged for workers to work in. Soft and hard wood dust and in many cases a chemical component of pressed wood product such as panel and board, formaldehyde, are key airborne contaminants in joinery and cabinetmaking operations. In December 2010 the eight and twelve hour WES for soft wood dust was dropped from 5 mg/m3 to 2mg/m3 while for hard it remained at 1mg/m3. The Short Term Exposure Limit (STEL) was withdrawn. A two year period was allowed for companies to implement the necessary changes to meet these new standards which came into effect in December 2012. These levels are determined using the Time Weighted Average (TWA) exposure over an 8 or 12 hour work day. It should be noted that the 12 hour TWA is temporary, as it should be lower than the eight hour WES (to allow for the longer exposure period, and the shorter recovery time). The twelve hour WES was kept the same as the eight hour WES for a period of time to allow companies some time to adjust to the new WES. The soft wood dust WES were lowered as the latest research indicates that adverse health effects can occur at concentrations lower than the previous WES.. These adverse health effects include wide ranging effects in the upper and lower respiratory tracts including potential cancers. Formaldehyde has an existing Workplace Exposure Standard of a ceiling of 1 part per million (ppm). To this was added in December 2010 a WES – TWA of 0.5ppm for an 8 hour shift and 0.33ppm for a 12 hour shift. There is no Short term Exposure Limit (STEL) for formaldehyde. The two new WES-TWA’s were added because it is somewhat difficult to measure peak formaldehyde exposures using sampling methods used in New Zealand. Formaldehyde appears to be a risk for those involved inter alia with pressed wood product including such board product as MDF. A one year period was allowed for those companies involved to comply.

Good Advice: eliminate, isolate, minimize.

The practical solutions to dealing with hazardous airborne dust are simple and have been widely followed by those companies involved with wood based product manufacture. The most common has been the replacement of old machinery using poor extraction ventilation and replacing with more efficient dust capture and extraction. Local extraction ventilation can be used and enclosing the manufacturing process concerned. Good housekeeping practices help to reduce any build up inside machinery and work places. The use of vacuum methods to collect excess dust is considerably more efficient than use of brooms or air jet hoses for example.

There is an ongoing need by factory owners and operators to review their operating equipment and their extraction and ventilation machinery should also be part of that ongoing review. The underlying concept of the Health and Safety in Employment Act 1992 is ‘eliminate, isolate, minimise’. It is all aimed at the protection of those in the work place. Although MBIE has the ability to prosecute substantive penalties for breaches of the various pieces of legislation involved, the preferred method is to work through all other options first such as liaising with the employer or, looking at a lower level enforcement if a negotiated agreement with the employer fails.

(Separate box)

The Role Of The Ministry of Business, Innovation and Employment (MBIE)

JOINERS Magazine put a couple of specific questions to MBIE on the role of MBIE and the issue of enforceability:

What is the basis for determining whether a factory should be visited with regard to health and safety issues?

A factory may be visited by health & safety inspectors as part of a project such as the Safe Use of Machinery Project (, or randomly as part of regular inspections. An inspector will often make an appointment, depending on the purposes of the proposed visit, but advance notice is not legally required. A visiting inspector is only required to give notice where the visiting time or circumstances are other than what would be usually be considered ‘reasonable’.

How often are factories visited?

Each year health & safety inspectors visit about 5000 workplaces. These are proactive, planned visits and are not usually triggered by a report of serious harm or a health and safety complaint. In selecting which workplaces to inspect regional offices take the following factors into account: the likely hazard profile of a particular workplace; the scale of potential or actual harm; knowledge of the workplace’s past health and safety performance and identified priority areas.

What clout does MBIE have?

Any action taken by a health and safety inspector during a workplace visit will depend on the circumstances. If workplaces have effective health and safety systems or the issue is minor, the inspector may offer information and advice. If more serious breaches of the law are observed, the inspector will use enforcement interventions The Ministry uses its enforcement powers when it is unable to get voluntary compliance with the law or the matter is such that a duty-holder needs to be held accountable for failure to meet minimum standards. This covers both the Health & Safety in Employment Act 1992 and the Hazardous Substances and New Organisms Act 1996. Enforcement is used as a complement to other strategies such as engagement, education and enablement. The Ministry’s response to any observed breach of legislation is to choose the enforcement intervention that will see hazards eliminated, isolated or minimized and influence future compliance. Beyond a process of written warnings and notices, court proceedings are only considered once a breach has been identified and there is evidence to sustain a prosecution and compliance cannot be gained otherwise, or there has been deliberate or careless disregard for the health and safety of others or there has been deliberate attempt to make economic gain through non compliance or the public interest requires a prosecution.

If a company wants advice how and who do they talk to at MBIE?

Companies can contact their local Health & Safety office or the Ministry’s information officers are able to offer advice and guidance material through 0800 20 90 20 or