Peatlands cover about 5% of the earth’s surface. Their total reliance on water to maintain natural processes makes them highly significant terrestrial ecosystems. They are under increasing pressure from human development and drought conditions. In this concluding article, Gavin Parker discusses the health and safety issues surrounding peat fires.
For firefighters and contactors engaged in activities at or near peat fires, health checks can be done by trained agency or contracted personnel. These can occur prior, during and at the end of a working shift. These checks can include blood pressure, blood carbon monoxide levels, blood oxygen saturation and other general health information, in accordance with agency procedures.
Assessing air quality is an important function at peat fires for the health and safety of firefighters, contractors and the general public.
Monitoring equipment can include small individual carbon monoxide (CO) monitors that are worn by firefighters and equipment contractors. Other multi-gas and particulate detection equipment that is either directly or remotely monitored can also be deployed near the fire or the broader community area. Additional portable equipment from state or territory Environmental Protection Agencies (EPA) supported by other agencies such as State Emergency Service (SES – Victoria) may also supplement other permanently fixed equipment that may already be in place. Monitoring procedures and guidelines for exposure limits, operations area and community advice and warnings in this type of environment may be detailed in agency procedures.
Smoke plume modelling may also be done. This can produce predictive information on affected areas based on fuels, type of burning, current and predicted weather conditions, and can be used together with air-monitoring information for community warnings and planning for firefighting operations.
Smoke, ash and dust hazards
Unlike surface fires, peat fires smoulder at a low temperature. They produce little flame and much smoke, which can become a threat to public health. Peat smoke differs from normal wood smoke because of what is in the peat and how it burns. Peat consists of partially decomposed vegetation and contains varying amounts of carbon, sulphur and nitrogen compounds.
Peat smoke is a complex mixture of substances produced during fuel combustion. Major components include fine Particulate Matter (PM) in the by-products of combustion. PM2.5 refers to particles of 2.5-micron diameter and PM10 refers to particles of 10-micron diameter, and these particles can be inhaled and cause irritation of the respiratory system. Smoke also contains fine particles, water vapour and gases including carbon monoxide, carbon dioxide and nitrogen oxides. Some peat fires may produce sulphur compounds which can be odorous. Smoke from peat fires may tend to form a low-lying haze with thermal inversion acting like a lid.
Peat soils have very little inherent structure and near the surface are mainly bound together by roots. As a result, when disturbed they can be prone to producing very fine dust, particularly as it dries or oxidises.
Both ash resulting from fire or fine peat dust PM that is ether disturbed by wind and machinery is also a significant health hazard and can reduce visibility.
Where the incident controller deems that CABA/SCBA is not required, P2 (N95) particulate respirators may be used in combination with atmospheric CO monitoring.
Protection against smoke, ash and dust
- Appropriate Personal Protective Clothing (PPC) including gloves.
- Personal Protective Equipment (PPE) including respiratory protection such as P2 or N95 (NIOSH & CE standard) masks are important when working near peat smoke and dust.
- Safety goggles for eye protection in dust and ash conditions.
- Checking soil pH levels.
- Hand and face washing.
- Air monitoring.
- Health monitoring.
Reducing smoke, ash and dust emissions
- The use of foam and CAFS can also smother the fire, not only suppressing it but also significantly reducing smoke and dust emissions.
- Using sprinklers, sprays or ground monitors.
- Using powered mist spray equipment (large-fan forced-water misting unit with up to 100m throw for both dust and fire suppression).
- Using other dust-suppression equipment such as road water sprayers on tracks.
- Reduce unnecessary vehicle and machinery movement.
- Emergency soil stabilization to reduce peat wastage and dust.
- Maintaining some moisture on extinguished areas and continue dust mitigation even after the fire has been extinguished.
- Removal of people from the area during times of thermal inversion with smoke remaining in the area.
Methods to reduce or eliminate exposure to smoke and dust
- Working upwind or from a flank, out of the smoke, ash and dust
- The use of long-reach sprays from handlines or ground monitors, sprays and sprinkler systems that can suppress the fire conditions without unnecessary exposure to smoke.
- Using ground monitors and handlines with sufficient water throw to avoid exposure.
- Machinery operations should utilize equipment with closed ventilated cabins with air-filtration systems to reduce the concentrations of peat smoke particulates and dust.
- Wetting the area down or consider using foam or Compressed Air Foam Systems (CAFS).
- Adjusting work priorities to take advantage of favourable wind conditions and the use of other specialized dust-suppression equipment and water additives could also be considered.
Some peatlands tend to produce shallow root networks and roots close to the surface. Trees can be a reliable marker for estimating depth of loss of material at peat fires.
The loss of peat matter from the ‘root plate’ can lead to the risk of trees falling. This can result in a high risk for people and equipment in the area. A hazard tree assessment and consideration of exclusion zones should be undertaken if trees have been impacted by peat fires.
Both unburnt and particularly burnt and burning peat pose significant challenges and risks in access with vehicles, machinery as well as people moving on foot. The main risks associated with access include, but are not limited to, the following:
- On unburnt peat the risk of getting vehicles and machinery stuck or bogged. While surfaces may seem solid enough to carry vehicles, once the crust is broken, the surface may not provide support.
- On burnt ground what may seem to be ground that has been extinguished, can hide deep burning ash that can be dangerous, particularly if moving on foot.
- Burnt areas can also provide various depths of ash or mud once water is applied. This can result in people becoming ‘stuck’.
- Loss from peat material from the ‘root plate’ of plants and trees can provide trip hazards, particularly if moving on foot.
- Work done by machinery can result in removal or disturbance of material and vegetation that can restrict or limit movement by other vehicles or people.
- Soil disturbance by vehicle movement can result in them getting stuck or bogged. Some areas may have to be avoided or restricted to vehicle or machinery with low ground pressure. In areas where movement is restricted, such as gateways or tracks, crushed rock may have to be brought in and spread to improve the surface.
Safety around machinery
Standard safety measures for working near machinery and equipment apply to peat fires. Dynamic risk assessments should be undertaken, and consideration should be given to equipment types and accessories that may be unique to a peat fire environment in comparison to surface fires.
Acid sulphate soils
Common in many parts of the world, (Coastal and Inland) acid sulphate soils (CASS & IASS) are saturated with water, almost oxygen-free and contain microscopic crystals of iron sulphide minerals (commonly pyrite).
Acid sulphate soils are safe and harmless when not disturbed. However, if acid sulphate soils are dug up or drained, they then come into contact with oxygen. The pyrite in the soil reacts with the oxygen and oxidizes.
This process turns pyrite into sulfuric acid, which can cause damage to the environment, buildings, roads and other structures. The acid also attacks soil minerals, releasing metals like aluminium and iron. Rainfall can then wash the acid and metals from the disturbed soil into the surrounding environment. Details of the environmental impact of CASS & IASS is beyond the scope of this article.
To identify when acid sulphate soils are disturbed, the iron released from the pyrite oxidation forms a range of brightly coloured minerals: first yellow, then brown then red. Cracks open on the soil surface, and the soil shrinks as it dries out. Most importantly, the soil pH drops from nearly neutral to extremely acidic, often below pH 2.
Acid sulphate soil and water can irritate the skin and eyes, and so it is important to reduce unnecessary exposure to the skin of burnt and unburnt peat. Consideration may need to be given to additional measures for personal hygiene, particularly hand and face washing, cleaning of PPE and PPC as well as other equipment.
The full range of health and safety hazards that would normally be associated with surface fires are also generally present at peat fires. But just as peat fires present unique challenges in suppression, the same is so for health and safety. This is due to the peat-fire environment, the type of fuels, quality and duration of exposure to these hazards. We need to be aware of the risks and take appropriate steps to eliminate or manage them.
For more information, email G.Parker@cfa.vic.gov.au
- Peat consumption and carbon loss due to smouldering wildfire in a temperate peatland, G. Matt Davies, Alan Gray, Guillermo Rein, Colin J Legg (2013)