Arborists are expected to work in environments which experience extremities of weather. In fact, some arborists consider pushing themselves in extreme conditions as proof of their toughness and ability. Wearing hot chainsaw pants and chaps historically has been part of the challenge.
However, during the summer months, the temperatures experienced may present a clear and present danger to the arborist.
Even in the colder seasons, in locations not normally associated with high average temperatures, the effect of heat can be both significant and pronounced.
There has been some excellent research into the importance of hydration but little to date on the effect of PPE, specifically chainsaw pants and chaps. Existing scientific studies allow us to quantify the impact of heat on safety and productivity
1. High Temperatures and Physical Safety
Humans have a core body temperature of 37°C. This core temperature is finely balanced and can be altered by a change in 6 factors.
- Air Temperature
- Radiant temperature
- Air movement (wind speed)
- The metabolic heat generated by human physical activity
An arborist will generate significant metabolic heat due to the physical nature of the work. This is often in situations where the air temperature may be high, wind speed low, and humidity high.
Chainsaw chaps and pants can become burdensome and heighten the effects of heat, clothing being the biggest heat trap, contributing to the problem.
The effects of heat can be pronounced and deadly.
As the core body temperature rises above 38°C, there is an increasing effect on the working capacity of the arborist, both physical and mental.
Symptoms of heat exhaustion can start.
There are two types of heat exhaustion.
- Water depletion with symptoms starting with excessive thirst, weakness, headache and leading to loss of consciousness.
- Salt depletion with symptoms including nausea and vomiting, muscle cramps, and dizziness.
From 40°C upwards, life-threatening ‘severe hyperthermia’ or heat stroke may occur.
Common symptoms in addition to a high body temperature are:
- Change in mental state or behaviour resulting in confusion, agitation, slurred speech, irritability, delirium, seizures and coma
- Abnormal sweating with either the skin feeling hot and dry if the heat stroke cause is mainly hot temperature or dry and slightly moist if the cause is strenuous exercise
- Nausea and vomiting
- Flushed skin
- Rapid, shallow breathing
- Increased heart rate
Recommended immediate treatment involves cooling the victim by getting the person to a shaded area, removing clothing, applying cool water to the skin, using a fan and placing ice packs in areas that help chill blood vessels quickly such as around the neck, inner wrists, back of knees, inner thighs and under the armpits. Drinking cool beverages is also recommended. Emergency services should always be notified.
Without immediate treatment, the injuries to the victim can be severe. Organs like the brain, heart, kidneys and muscles can be permanently damaged as a result of swelling and stress. And the damage gets worse the longer treatment is delayed. Death from heat stroke is possible.
The risk to the arborist is magnified because they are likely to be working at height and with potentially dangerous machinery. In such an environment, mistakes could end up being deadly.
2. The Impact of Hot Chainsaw Pants and Chaps on Profitability
In addition to the safety issue, heat illness also impacts profitability.
The effect of heat on the body can manifest itself not only physically but also financially. It is possible, through previous research on temperatures in working environments, to correlate incremental increases in temperature to productivity loss, then quantify that loss financially.
There have been a number of studies which have measured the mental capacity of office workers as the temperature increases. It would be reasonable to suggest this would also hold true for other working environments. Taking into account numerous studies and then averaging the results shows a 2% reduction in productivity per degree temperature rise, when the temperature is above 25°C (75°F).
This is represented in the following equation:
P (%) = 2 x (Temperature, °C) – 50
This equation shows a linear line between productivity and the temperature, with a 2% drop in productivity realised at 26°C, rising to a 20% decrease in productivity at 35°C (95°F) .
We are using temperature to simplify the discussion. Heat Stress Index is the correct measure that takes into account humidity. Other factors like wind impact the effect of heat.
An arborist working in Brisbane, Australia, will experience 8 months of the year where the average high exceeds 25°C.
In the United States, Florida will see 7 months of the year with an average high above 25°C. For North Carolina, it will be 5 months. For New York, 3 months.
If we take the scenario of one week in summer where the temperature rises above 25°C for 5 hours per working day, peaking at 28°C, then we can quantify the loss of productivity cost based upon the billable rate charged by the company.
For 1 hour of the day the temperature is at 26°C (79°F) = 2% productivity lost (represented as 0.02hrs)
For 1 hour of the day the temperature is at 27°C (81°F) = 4% productivity lost (represented as 0.04hrs)
For 1 hour of the day the temperature is at 28°C (83°F) = 6% productivity lost (represented as 0.06hrs)
For 1 hour of the day the temperature is at 29°C (81°F) = 4% productivity lost (represented as 0.04hrs)
For 1 hour of the day the temperature is at 26°C (79°F) = 2% productivity lost (represented as 0.02hrs)
Total = 0.18 hours
What does that mean in financial terms.
0.18 x $80/hour = $14.40/day | $72/week | $288/month
This is per person, the larger the crew the larger the potential loss in productivity ($) for the company.
For those locations where the average high temperature exceeds 25°C for multiple months, with many of the peak weeks seeing the temperatures above those used in the scenario, then the cost could be quite staggering.
Bear in mind that these generalised studies do not take into account the productivity impact of people in highly strenuous roles wearing heavy and hot chainsaw protective gear as well as harnesses and other climbing equipment. It is likely that for arborists and tree workers the productivity impacts would occur at much lower temperatures with bigger productivity impacts.
The Arborist industry worldwide is suffering from a skilled labour shortage. Even if your goal is to maintain your business, retaining your top people is key to your future.
Taking a proactive approach to heat management shows a basic empathy for your people. Supplying your top people with better equipment and apparel can act as an important retention tool while progressing your safety goals.
3. Heat Management Regulation (and Self Regulation)
The arboriculture industry has a large element of machismo as part of its culture. However, pushing physical limits in the heat is dangerous. Like any other hazard, heat needs to be assessed and managed.
This is increasingly becoming no longer optional. In California, the CAL-OSHA Heat Illness Prevention Regulations have specific heat illness and prevention programs with penalties for employers who fails to comply. It should not take government action for arborists and other tree workers to prioritize heat management as an important issue.
4. Heat Management Factors to Consider When Selecting Chainsaw Protective Apparel
In situations where chainsaw protective clothing is either required by legislation, is mandated by the employer, or is worn by the arborist’s own volition – there are steps that can be taken to help reduce the danger from excessive heat build-up.
The human body will try to regulate the core body temperature by taking three progressive steps.
First, blood flow to the skin is increased, moving heat from the core.
Next, breathing is intensified and becomes heavier as you expel heat.
Finally, you begin to sweat. However, for sweat to be an effective coolant it must be able to evaporate. If it is trapped under clothing, and/or in a situation where high humidity is present, sweating may not be as efficient.
In order for the final stage of core body temperature regulation to be effective, chainsaw pants and chaps need to be designed to allow for effective cooling
Given this, the ability of a garment to reduce heat build-up should be a key criteria of the decision-making process . Overall, the trouser should work with the arborist, rather than against them, decreasing the effort required to move through the trees or on the ground.
Here are the top factors to consider.
a. Chainsaw fabric
The first thing to address is the chainsaw protective fabric. Low cost standard chainsaw fabric is essentially a layer of insulation. The old belief that hotter and heavier means safer no longer applies when it comes to chainsaw fabric. Cut resistant technical fibres like UHMWPE (Dyneema) and new manufacturing methods means that less layers of thinner and breathable fabric can provide better chainspeed performance than 8+ layers of traditional fabric.
b. Other fabrics
Low-cost outers can appear durable as well as having benefits like water and oil resistance. However, these low-cost fabrics do not breath well and are heavy and stiff to wear
Technical ripstop 4-way stretch fabric breathes well and make for easier movement while still being durable.
Technical fabrics can also wick moisture by transferring moisture away from the body, helping with cooling.
Some fabrics even have what is regarded as ‘cooling capabilities’ for their ability to transfer heat away from the body and allow circulation of air.
The advanced fibre, Nilit Breeze, has been proven to lower the body temperature by almost 1 degree (research conducted by Centexbel Textile Research Centre, Belgium).
c. Design features of chainsaw pants and chaps
Chainsaw pants or chaps that help maintain the core body temperature and full function of the arborist is likely to offset productivity losses to a limited degree (dependent upon both the arborist and the control environment) by keeping the arborist cooler for longer.
Features to look for:
Breathable outers and chainsaw fabric reduce or even prevent “wetout” where the fabric gets completely wet making it sticky and hard to move in.
The use of mesh vents to assist with air circulation (and sweat evaporation) with maximum, unobstructed air flow. Zipped vents are good for seasonal pants but not in the heat because the zip limit the air flow. Design decisions like leaving the leg open to provide air flow rather than using a gaiter also help increase cooling efficiency.
A trouser designed purposely for an arborist, taking into account their movement and body positions required, will include full 4 way stretch. Stretch and flex makes the work easier meaning less exertion.
Design and cut
The cut of the trousers can also impact cooling performance. Traditional arborist pants have a high back. This adds unnecessary additional fabric coverage. Look for pants and chaps designed for the summer months with all features that impact performance in the heat removed. For example, Clogger’s Zero chainsaw pants do not have a back pocket due to the impact on stretch and breath ability. Focused design objectives ultimately add up to better performance.
The weight of the trouser must be taken into consideration. Weight makes for harder movement and more exertion. Even an additional 0.5 kg (1lb) is noticeable. Simply put, the lighter the trouser the less effort is required to move your body when wearing it.
Some people might like a skinny fit but tight fitting pants do not work well in the heat. Wearing loose-fitting and lightweight clothing helps promote airflow around the body, allowing heat to escape and cooling the skin. Loose garments also provide more comfort and minimize friction against the skin, reducing the risk of heat rash and other heat-related skin irritations. You do not want the pants too baggy though. Just loose enough to allow for good air flow. The combination of a looser fit and venting creates the best cooling results.
5. Go beyond the climber
Ground workers are also vulnerable to heat stroke.
Chaps have the advantage of an open back for cooling unless the chaps have calf protection. However, chaps are often designed to be durable and low cost rather than comfortable and cool.
More ground workers are choosing to wear pants rather than chaps for productivity and safety reasons. Chainsaw pants designed for the ground also need to take into account the risk of heat illness offering features that have been proven with climbers, like modern technical chainsaw fabrics, design elements like vents and advanced moisture and heat wicking fabrics.
Chaps with 360 calf wrap are essentially trousers. Working on the ground can be strenuous and sometimes without the shade of the canopy. Consider the design features that will aid cooling where applicable, when making decisions on pants and chaps for ground workers.
Clothing is a key factor in heat management.
There is a good argument that a small investment in clothing with better heat management features can deliver savings far beyond the small additional investment through increased productivity.
More importantly, heat stress makes for a poor work experience and is dangerous. Assess your risk and put the right plan together to mitigate it. Choosing chainsaw protective apparel that provides the coolest experience possible should be part of your plan.