
The other day I received my chainsaw certification. I am now licensed to chop. Yet somehow, I feel uncomfortable. First, I am not sure I did as well in my assessment as I might have done, yet I still managed to squeeze through. Second, and more important, I have learned that a chainsaw brings the potential for limitless damage. Plus, it has a huge effect on our fragile environment. In one respect I am an environmentalist and seek to preserve all around me. In others, I now have a licence to destroy all I hold dear. I need to find a middle ground.
Chainsaws have revolutionised forestry practices since their inception and have enabled rapid and efficient tree felling and processing. While they offer undeniable benefits in terms of labour reduction and economic gains, the environmental implications of their use, particularly with deforestation and climate change, are not always the best. There are also the effects of chainsaws on human health.
The Chainsaw’s Medical Beginnings
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The earliest prototype of the chainsaw was developed around 1780 by two Scottish doctors, John Aitken[i] and James Jeffray[ii]. It was created as a tool for the operation of symphysiotomy, a procedure used in difficult childbirth before the advent of modern obstetrics and Caesarean sections[iii]. Symphysiotomy involved cutting through cartilage and bone in the pelvis to widen the birth canal when a baby was too large to pass through. This early surgical chainsaw was a hand-cranked device with a chain of small cutting teeth, similar to a modern bicycle chain. It was more efficient than the earlier method of using a small knife or saw and made the procedure quicker, with less strain on both mother and surgeon.
The chainsaw developed further from there. By the 19th century, chainsaw-like surgical instruments were used in amputations and bone-cutting procedures. These evolved versions that were still small, manually operated, and designed for precision cutting. By the late 19th and early 20th centuries, engineers saw the potential for chainsaw-like mechanisms beyond medicine, particularly in forestry. The medical chainsaw had proven that a continuously rotating chain with cutting teeth could slice through tough materials efficiently.
A key figure in this transition was Bernhard Heine, a German orthopaedic surgeon, who developed the chain osteotome in 1830. This was a hand-cranked chainsaw-like device used for cutting bone[iv],[v]. Although it was still a surgical instrument, its design hinted at its potential for larger scale cutting applications.
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Development of the Modern Chainsaw
The development of the chainsaw continued. By the 1920s, the first motorised chainsaws were developed in Germany. These were large and heavy, but they were significantly faster than traditional axes and hand saws. In the 1930s and 1940s, lighter fuel-powered and electric chainsaws emerged, making them practical for widespread use in forestry. By the 1950s and beyond, advances in materials and engineering made chainsaws lighter, more powerful, more accessible to foresters, and eventually to the public.
From Surgery to Forestry to Everyday Use
What thus started as a tool for delicate bone surgery soon evolved into a powerful tool for forestry, and even for construction, landscaping, and emergency rescue. However, chainsaws have both advantages and disadvantages.
Advantages
Chainsaws offer several advantages that have cemented their role in forestry. These include:
· Efficiency and Productivity: Chainsaws enable rapid felling and processing of trees, significantly reducing the time and labour required compared with manual methods.
· Economic Benefits: The efficiency of chainsaws translates into economic gains for forestry operations, allowing for higher output and profitability.
· Versatility: Modern chainsaws are designed to handle various tasks beyond tree felling, including pruning, limbing, and even milling timber on-site.
· Accessibility: Chainsaws have become more affordable and accessible, allowing small-scale and community-based forestry operations to manage resources effectively.
Disadvantages
Yet chainsaws have disadvantages, too. These include:
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· Deforestation: The efficiency of chainsaws has facilitated large-scale deforestation, leading to habitat loss, biodiversity decline, and disruption of ecosystems.
· Carbon Emissions: Chainsaws, particularly fuel-powered models, emit carbon dioxide (CO₂) and other greenhouse gases during operation, contributing to atmospheric pollution.
· Soil and Land Degradation: The removal of trees using chainsaws can lead to soil erosion and degradation, reducing the land's fertility and increasing sedimentation in waterways.
· Noise and Air Pollution: Chainsaws produce significant noise and emit pollutants, affecting both human health and wildlife.
Looking at these disadvantages in more detail:
Deforestation
The Amazon rainforest, often referred to as the "lungs of the Earth," has experienced alarming deforestation rates in recent times. Between August 2019 and July 2020, approximately 11,088 square kilometres of forest were cleared in the Brazilian Amazon alone, a 9.5% increase from the previous year. This surge represented the highest deforestation rate in over a decade[vi].
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Chainsaws played a pivotal role in this deforestation. Their ability to quickly fell trees makes them indispensable for clearing large, forested areas, whether for agriculture, mining, or urban development. However, this rapid tree removal has dire ecological consequences. Forests act as carbon sinks, absorbing CO₂ from the atmosphere. When trees are felled and either burned or left to decompose, the stored carbon is released back into the atmosphere, contributing to greenhouse gas emissions and climate change. Forest degradation, which includes the deterioration of forest health and quality, accounts for a significant portion of land-based carbon emissions. Estimates suggest that degradation contributes between one-third and two-thirds of these emissions[vii].
The widespread availability of chainsaws has also led to increased illegal logging activities. Uncontrolled chainsaw milling, where individuals or small groups harvest timber without proper authorisation or adherence to sustainable practices, has become a significant concern. This practice not only leads to substantial forest degradation but also undermines legal forestry operations and conservation efforts[viii]. In the United States, the prevalence of chainsaw use has been described as an epidemic, with extensive tree removal occurring across various landscapes. This widespread use further exacerbates environmental challenges[ix].
Carbon Emissions
Chainsaws contribute significantly to environmental degradation, particularly through carbon emissions. They have direct and indirect effects.
Direct Emissions:
Chainsaws, especially those powered by two-stroke engines, emit various pollutants thanks to an incomplete combustion process. One research study analysed chainsaw emissions during chestnut wood operations and found that the tools emitted substantial amounts of carbon monoxide (CO), volatile organic compounds (VOCs), and benzene (C₆H₆), all of which have detrimental environmental and health effects[x].
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In the broader context of fuel-powered landscape equipment, which includes chainsaws, the environmental impact is considerable. In 2011, such equipment in the United States emitted approximately 20.4 million tons of CO₂, accounting for a significant portion of non-road emissions[xi].
Indirect Emissions:
Beyond the direct emissions from their engines, chainsaws facilitate deforestation, leading to substantial indirect carbon emissions. Forests act as critical carbon sinks, absorbing CO₂ from the atmosphere. When trees are felled, this carbon-sequestering capacity is diminished, and the carbon stored in the biomass is released during decomposition or burning. Reducing deforestation is thus essential for mitigating climate change[xii].
In specific regions, the impact is even more pronounced. For instance, a USA study highlighted that forestry accounts for approximately one-third of Oregon's total carbon emissions, underscoring the significant role of deforestation in regional greenhouse gas outputs[xiii].
Soil and Land Degradation
The use of chainsaws in deforestation significantly contributes to soil degradation, leading to adverse environmental impacts. The removal of trees disrupts the soil structure and initiates processes that degrade soil quality. Beyond the physical removal of trees, the operation of chainsaws introduces pollutants into the soil. A research study evaluating the impact of three types of chainsaw lubricants on forest soil bacterial communities found significant changes in soil properties thanks to contamination[xiv]. The study observed alterations in soil respiration rates and shifts in bacterial community composition, indicating that lubricant spills can adversely affect soil health.
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With soil degradation comes land degradation. This is the decline in the quality and productivity of land because of natural processes and human activities. It results in loss of biodiversity, reduced soil fertility, disrupted water cycles, and increased vulnerability to extreme weather events. It can occur through various mechanisms, soil degradation being one. Yet there is also deforestation, desertification, salinisation, pollution and contamination, and climate change impacts. Land degradation is a real and developing problem.
Globally, land degradation is expanding at an alarming rate, with approximately 1 million square kilometres of land becoming degraded each year. This trend undermines efforts to stabilise the climate, protect biodiversity, and ensure sustainable food supplies. The cumulative degraded area has reached 15 million square kilometres, an expanse larger than Antarctica. Unsustainable agricultural practices, including deforestation facilitated by chainsaw use, are primary drivers of this degradation[xv].
Noise and Air Pollution
Chainsaws, while essential for forestry and land management, are significant contributors to both noise and air pollution. Their operation poses health risks to users and environmental challenges because of high noise levels and the emission of harmful pollutants.
Noise Pollution
Chainsaws are known for their high noise output, which can have immediate and long-term health implications. The noise levels produced by chainsaws can reach up to 120 decibels (dB), a level that can cause irreversible hearing damage after only a few seconds of exposure without proper hearing protection[xvi].
For context, a typical conversation occurs at about 60dB, and noise levels above 85dB are considered hazardous over extended periods. The National Institute for Occupational Safety and Health (NIOSH) recommends a maximum exposure limit of 85dB over an eight-hour working day. Exposure to noise levels over this limit increases the risk of noise-induced hearing loss[xvii]. A chainsaw going full throttle can reach a peak level of at least 110dB.
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Noise generated by chainsaws can exceed legal limits during most or all activities. Such exposure can lead to significant health issues, including hearing loss, increased blood pressure, and heightened stress levels. Much research has been undertaken over many years into the effects on human health of noise. In brief, noise is bad for you. However, it is not just the level of noise, but also its type. The information conveyed by noise is very often more relevant than the sound level. The first signal detection is mediated by a subcortical area of the human brain - the amygdala. For this reason, even during sleep the noise from aeroplanes or heavy goods vehicles may be categorised as danger signals and induce the release of stress hormones. This can lead to an increased risk of myocardial infarction (heart attack)[xviii]. Consequently, if it so happens a chainsaw is heard by an environmentalist, anything is possible.
Air Pollution
Chainsaws, especially those powered by two-stroke engines, emit various pollutants because of incomplete combustion. These emissions include carbon monoxide (CO), volatile organic compounds (VOCs), and fine particulate matter (PM2.5), all of which have detrimental effects on air quality and human health. A comparative analysis of exhaust emissions from chainsaws revealed that CO constitutes about 6.2% of chainsaw exhaust, while hydrocarbons make up approximately 1%[xix]. These emissions are considered harmful to humans and contribute to environmental pollution.
VOCs comprise volatile hydrocarbons and other organic molecules released into the atmosphere. They may have biogenic or anthropogenic sources. In the UK it is estimated that less than 5% of the VOCs emitted into the atmosphere are emitted from vegetation. The rest comes from transport, including distribution and extraction losses (50%), solvent use (30%) and other industrial processes (15%). Chainsaws may be added to this list. Road transport alone accounts for 30% of VOC emissions[xx].
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In 2020, fuel-powered lawn and garden equipment, including chainsaws, across the United States emitted more than 30 million tons of carbon dioxide (CO₂)[xxi], 68,000 tons of nitrogen oxides (NOx), and 350,000 tons of VOCs into the atmosphere. These pollutants also contribute to the formation of ground-level ozone, which can trigger respiratory issues and other health problems. Passenger vehicles have also been the focus of extensive emissions studies. According to the US Environmental Protection Agency (EPA), the average passenger vehicle emits about 411 grams of CO₂ per mile driven. This figure is based on an average fuel economy of 21.6 miles per gallon and an annual mileage of approximately 11,400 miles. The result is about 4.7 metric tons of CO₂ emissions per year per vehicle[xxii].
Meanwhile, the fuel consumption rates for chainsaws vary depending on the model and how it is used. For instance, the GRAPHITE 58G954 petrol chainsaw consumes approximately 1.63 litres of fuel per hour[xxiii]. Working on the assumption that fuel combustion produces about 2.31 kilograms (2310 grams) of CO₂ per litre burned[xxiv], the CO₂ emissions for the GRAPHITE 58G954 chainsaw can be estimated as 3765.3 grams CO2/hour.
Calculations will vary but a best guess is that one hour of chainsaw operation produces CO₂ emissions equivalent to driving a passenger vehicle for approximately 41.4 miles. Next time I have a chainsaw in my hands, and am surrounded by trees, I will remember that.
Psychology of chainsaw use
It is not that chainsaws think - although they may do for all I know - but chainsaw operators certainly do, as well as folk within earshot. The psychological effects of chainsaws on both the operator and those around can be significant. Tree surgery is the UK’s most demanding occupation, physically and mentally. Tree surgeons, and chainsaw operators even at ground level, must balance the need for speed with the imperative of safety. Facing these pressures daily can have a devastating effect on mental health[xxv].
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There are various issues that need to be considered:
Noise (once again)
Chainsaws are in themselves a source of noise pollution and produce noise levels that often exceed safe thresholds. The health effects are undeniable, as I have already outlined. One research study in 2022[xxvi]investigated the physiological and subjective responses to chainsaw noise compared with natural forest sounds. The findings revealed that exposure to chainsaw noise was associated with increased feelings of fatigue and tension, as well as heightened physiological arousal, indicating a stress response. In contrast, listening to forest sounds elicited feelings of relaxation and improved cognitive function.
Further research, in 2024, examined the effects of chainsaw noise on workers' concentration levels in industrial forest plantations[xxvii]. The study found that higher noise intensities negatively impacted concentration, leading to decreased work performance and increased mental fatigue. This cognitive strain can exacerbate psychological stress, highlighting the need for effective noise management strategies in forestry operations.
Physical Workload
The physical demands of chainsaw operation are considerable, often leading to significant physiological strain. Research has assessed the physiological workload of chainsaw operators during tree felling activities. The study reported elevated heart rates indicative of heavy physical labour, which can contribute to physical fatigue and, subsequently, psychological stress[xxviii]. The continuous physical exertion required in chainsaw operation underscores the importance of addressing both the physical and mental health of forestry workers.
Posture
Maintaining improper body postures during chainsaw use can lead to musculoskeletal disorders, further impacting psychological well-being. One study[xxix] investigated the impact of different body postures on heart rate strain during tree felling. The findings indicated that certain postures significantly increased heart rate, suggesting higher physical and cardiovascular strain. This increased physical strain can lead to discomfort and pain, contributing to psychological distress among operators.
Vibration and chainsaws
Chainsaws can produce vibration levels ranging from approximately 2.9 to 7.1 m/s², depending on the model and condition of the equipment[xxx]. There are different ways of measuring vibration - displacement, velocity, or acceleration. Acceleration, used for high-frequency vibrations, is often measured in m/s². When measuring acceleration to quantify vibration, it is the rate of change of velocity of a vibrating object that is being assessed. That is, how the speed of an oscillatory motion increases or decreases over time.
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Levels of 2.9 to 7.1 m/s² can exceed the permissible exposure limits defined for an eight-hour working day, indicating a significant risk of vibration-related health effects for operators. The use of a chainsaw can exceed the Exposure Limit Value (ELV) of 5.0 m/s² A(8) for hand-arm vibration (HAV) in the UK, depending on the type of chainsaw, how long it is used, and the specific working conditions.
There are typical levels for different kinds of chainsaw:
· Petrol Chainsaws: these typically produce vibration levels between 5 and 9 m/s² at the handles.
· Electric and Battery Chainsaws: these are usually lower but can still range from 3 to 7 m/s².
These different vibration levels can influence the length of time for which a chainsaw might be used. For example, if an Exposure Points System (based on HSE guidance) is used:
· At 5 m/s², the ELV (5.0 m/s² A(8)) is reached in about 2 hours of actual cutting time.
· At 7 m/s², the ELV is reached in around 1 hour.
· At 9 m/s², the ELV is reached in about 35 minutes.
The A(8) stands for the daily exposure value normalised to an 8-hour reference period. It is a standardised way of measuring and comparing vibration exposure levels over a full working day, even if the actual exposure occurs over a shorter period. It allows employers to compare different work scenarios on the same scale, to ensure exposure limits are not exceeded over a typical shift, and act based on standardised risk assessment methods.
Sadly, chainsaw use often exceeds the daily ELV, especially if the tool is used for extended periods.
Vibration-Induced Disorders
There are established vibration-induced disorders that can appear should there be prolonged use of chainsaws. This usage exposes operators to vibrations that may lead to conditions such as hand-arm vibration syndrome (HAVS) and carpal tunnel syndrome[xxxi]. These disorders are characterised by symptoms such as numbness, tingling, and loss of grip strength, which can significantly impact an individual's quality of life and mental health.
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The result of too much vibration can not only be vibration-induced disorders, but also physiological and psychological stress, increased heart rate, elevated cortisol levels, and impacts on cognitive function and fatigue. One research study measured the changes in heart rate and body vibration among machine operators and found that physical vibration significantly contributed to operational stress[xxxii]. Chronic exposure can be even worse and may result in heightened anxiety and other psychological disturbances.
Clearly, the chainsaw in my hand is no straightforward tool. It is an item I must treat with respect.
Here goes.
***
Hashtags
#ChainsawUse #ForestryTools #DeforestationImpact #EnvironmentalEffects #SustainableForestry #ClimateChange #CarbonEmissions #LandDegradation #ForestConservation #ChainsawSafety #NoisePollution #AirQuality #TreeFelling #EcoAwareness #GreenLiving #SustainablePractices #ReforestationEfforts #WildlifeConservation #EnvironmentalScience #SustainableLogging
References
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