Summary
• Process guidance notes set down requirements regarding control of air pollutants.
• Defra is starting the consultation process to review each process guidance note.
• Consideration will be given to particulate matter, nitrogen oxides, solvent and carbon emissions.
• Some PGs could be removed if they aren’t required by European Directives.

Many timber sites are subject to regulatory control for processes which could have an adverse impact on the local atmosphere. A degree of consistency is introduced to this control by the presence of process guidance notes which set down the normal requirements with regard to the control of the specific air pollutants. There are over 80 guidance notes, with the most relevant to timber sites being:

• PG6/2: Manufacture of timber and wood based products: processing >1,000m³ timber or purely sawing >10,000m³;
• PG1/12: Wood combustion in boilers rated from 0.4 to 3MW net rated thermal input;
• PG6/33: Wood coating using > 5 tonnes of organic solvent per year.

Sites operating above these thresholds should have permits for each process issued by local authorities (England and Wales) or the Scottish Environmental Protection Agency. Each permit will contain conditions derived from the relevant process guidance note and sites are required to upgrade their processes accordingly.

The written requirements of the guidance notes have remained unchanged since their last review, which ended in 2004. Defra is just starting the consultation process with regard to the forthcoming review of each process guidance note. At this stage, consultation is being undertaken on the review process rather than individual notes, but it has already flagged up some issues of potentially costly concern for the sector.

The 2004 review of the notes mainly saw cosmetic changes, such as the introduction of much longer and more impenetrable guidance notes – but at least these were made available free of charge on the internet for the first time.

Wood combustion

One of the main points of contention in the notes was the carbon monoxide (CO) emission limit for wood combustion. For some time the limit has been set on a site specific basis according to what could be achieved by the plant (often 400mg/m³). Defra proposed a tightening of the limit to 150mg/m³ which, according to the British Furniture Manufacturers trade association, would have resulted in 87% of permitted plants being unable to meet such a limit. The change was successfully argued against.

For the forthcoming round of reviews, it appears likely that there will be multiple battles to fight. The government has committed itself to reductions in a wide range of atmospheric pollutants in recent years. The policy of eradicating manufacturing from the UK has been successful in allowing Defra officials to claim emission reductions in many areas. Naturally the process results in much higher global emissions as processes switch to less regulated economies, but this is not Defra’s problem. A range of pollutants are mentioned in the general consultation and consideration will be given to inserting generic clauses into all relevant guidance notes for the following:

• PM2.5 and PM10: very small particulate matter (less than 2.5 and 10 microns in diameter respectively). These are of concern due to the fact that they will be inhaled deep into the lungs and they are linked to cancer. If a general limit is brought into the UK, it could be relevant to all three timber notes;

• NOx or nitrogen oxides: generated by combustion above 650OC – NOx would be relevant to wood combustion. At present, it is set as a limit on large scale combustion plant – for example, power stations. However, certain European countries such as Germany already set NOx limits for their small scale wood combustion plant;
• VOCs – volatile organic compounds or solvent emissions. Most sites which are regulated under the wood coating guidance note can rely on their solvent inventory to demonstrate compliance and do not have to monitor VOC stack emissions. However, a general VOC limit would threaten to reverse this situation, requiring physical monitoring in addition to paper-based calculations;
• CO2 emissions: with the government committing itself to a range of increasingly stringent carbon dioxide reduction targets, civil servants are now trying to work out how these could actually be met in the real world.

If a raft of new pollutants enter the guidance notes, there will undoubtedly be a host of new emission limits, with the latter requiring monitoring – either on an annual or a continuous basis. Some manufacturers will be aware of how costly and sometimes pointless, monitoring can be.

The carbon monoxide (CO) limit in the wood combustion guidance note provides a good example. An emission limit for CO has historically been set, not because it is a pollutant of concern, but because it is an indicator of combustion efficiency. Continuous monitoring packages for CO, particulate and temperature are typically in the £20,000-30,000 range. In the case of CO, extractive sampling is used and the system will invariably be unreliable and costly to maintain. Furthermore, if adverse CO results are recorded, there is not too much that can be done other than significant boiler upgrade or replacement. At the last review of the guidance note, Defra was urged to consider alternatives to CO emission limits, but no changes were made.

Wood dust

Another suggestion at the last review was the removal of PG6/2 altogether. This process guidance note focuses on the safe removal and containment of wood dust. Such control is essentially unnecessary as it simply duplicates other environmental controls. For example, Part III of the Environmental Protection Act (EPA) gives powers to local regulators regarding the control of neighbourhood nuisance. Part II of the EPA and the associated duty of care regarding waste places a duty on sites to keep waste secure and contained. Furthermore, the Water Resources Act makes it an offence for loose dust to enter controlled waters via surface water drains.

Defra did not remove the PG6/2 guidance note, but there have been subsequent consultations regarding the identification of regimes which are not required by European Directives and which could safely be removed. PG6/2 has been suggested as one such candidate, so there is a glimmer of hope that such unnecessary control will be removed.

In conclusion, if Defra gets its own way, it is likely that the scope of the process guidance notes will increase, new emission limits will be introduced, new clauses will be introduced to reduce the relevant pollutants and there will be significant additional costs for process operators. Therefore, some lively debate will be required in the next year to ensure that a suitable balance between cost and environmental benefit is achieved.

Dr Alistair Bromhead is an independent health, safety and environmental consultant specialising in the furniture and timber industries www.abromhead.co.uk.