By Mollie Freilicher, with input from Dr. Dennis Ryan

Arborists are often working in all seasons and in many types of weather. Each season has its challenges. One of the biggest challenges in winter is – not surprisingly—the cold. Make sure that you and your crews are staying warm enough to work safely and comfortably. Some things to consider:

Windchill is mathematically derived and seeks to measure the effect of wind and temperature on the body. There are different ways of calculating it. The National Weather Service (NWS) uses temperature and wind speed, though other entities (like AccuWeather) may use additional factors. According to the NWS, a temperature of 55 degrees F with a 30 mile per hour wind would have a windchill value of minus 19 degrees (see windchill chart). This means that your body will lose heat at the same rate as it would if the air temperature were minus 19 degrees without any wind.

While there is lots of debate about windchill (see here and here), the fact is: the colder it is, and the windier it is, the less able our bodies are able to keep up with heat loss. How that actually “feels” may be up for debate, but either way, when you are working outside in the cold and wind, keep windchill in mind.

Cold Weather Gear

Tips for working in the cold:

  • Dress in layers- if you get hot as you work, remove some of your middle layers
    • Inner Layer: Wear fabrics—wool, silk, or polypropylene— that will wick and keep moisture away from the body. Cotton is not a good choice. Good baselayers are critical.
    • Insulation Layer(s): An insulation layer will help you retain heat by trapping air close to your body. Synthetic fibers or natural fibers, like wool or goose down, or a classic fleece work best.
    • Outer Layer: The outermost layer helps protect you from wind, rain, and snow. It should be tightly woven, and water and wind resistant. To help prevent overheating, an outer layer that has some venting options is best.
    • Many tree climbers wear an insulated vest; the vest protects the chest and back, but leaves the arms free while climbing.
  • Stay dry
  • Wear a hat or warm beanie under hardhat (again, wool, silk, polypropolene)
  • Wear a balaclava, mask, or neck gaitor to cover the face, mouth, and neck (again, wool, silk, polypropolene)
  • Wear insulated gloves

Avoiding frostbite and hypothermia (adapted from the Centers for Disease Control)

Hypothermia is caused by prolonged exposures to very cold temperatures. When exposed to cold temperatures, your body begins to lose heat faster than it’s produced. Lengthy exposures will eventually use up your body’s stored energy, which leads to lower body temperature. Body temperature that is too low affects the brain, making the victim unable to think clearly or move well –

a dangerous situation for anyone, and particularly arborists who may be working aloft or with sharp tools (or both!). This makes hypothermia especially dangerous, because a person may not know it is happening and won’t be able to do anything about it. Check in with yourself and your crew. Is anyone experiencing these symptoms?

  • shivering, exhaustion
  • confusion, fumbling hands
  • memory loss, slurred speech, drowsiness

If so, Don’t Wait – Take Action!
If you notice any of these signs, take the person’s temperature. If it is below 95° F, the situation is an emergency—get medical attention immediately. For more information on what to do.

Frostbite is a bodily injury caused by freezing that causes a loss of feeling and color in affected areas. It most often affects the nose, ears, cheeks, chin, fingers, or toes. Frostbite can permanently damage the body, and severe cases can lead to amputation. For more information about frostbite and hypothermia, see Stay Safe & Healthy.

Recognizing Frostbite
At the first signs of redness or pain in any skin area, get out of the cold or protect any exposed skin—frostbite may be beginning. Any of the following signs may indicate frostbite:

  • a white or grayish-yellow skin area
  • skin that feels unusually firm or waxy
  • numbness

A victim is often unaware of frostbite until someone else points it out because the frozen tissues are numb. If you detect symptoms of frostbite, seek medical care. More information.

Advice on exertion
Cold weather puts an extra strain on the heart. If you have heart disease or high blood pressure, follow your doctor’s advice about performing hard work in the cold. Otherwise, if you have to do heavy outdoor work, dress warmly and work slowly. Remember, your body is already working hard just to stay warm, so don’t overdo it.

OSHA and the Cold
Although OSHA does not have a specific standard that covers working in cold environments, under the Occupational Safety and Health Act (OSH Act) of 1970, employers have a duty to protect workers from recognized hazards, including cold stress hazards, that are causing or likely to cause death or serious physical harm in the workplace. Frostbite, hypothermia, trench foot are the most common cold injuries.

Employers should train workers on the hazards of the job and safety measures to use, such as engineering controls and safe work practices, that will protect workers’ safety and health in the cold.

Employers should train workers on how to prevent and recognize cold stress illnesses and injuries and how to apply first aid treatment. Workers should be trained on the appropriate engineering controls, personal protective equipment, and work practices to reduce the risk of cold stress.

Employers should provide engineering controls. For example, radiant heaters may be used to warm workers in outdoor security stations. If possible, shield work areas from drafts or wind to reduce wind chill. (Not very practical for arborists, but may be appropriate in some situations.)

Employers should use safe work practices. For example, it is easy to become dehydrated in cold weather. Employers therefore, can provide plenty of warm sweetened liquids to workers. Avoid alcoholic drinks. If possible, employers can schedule work during the warmer part of the day. Employers can assign workers to tasks in pairs (buddy system), so that they can monitor each other for signs of cold stress. Workers can be allowed to interrupt their work, if they are extremely uncomfortable. Employers should give workers frequent breaks in warm areas. Acclimatize new workers and those returning after time away from work, by gradually increasing their workload, and allowing more frequent breaks in warm areas, as they build up a tolerance for working in the cold environment. Safety measures, such as these, should be incorporated into the relevant health and safety plan for the workplace.

Safety Tips for Workers

  • Your employer should ensure that you know the symptoms of cold stress.
  • Monitor your physical condition and that of your coworkers.
  • Dress properly for the cold.
  • Stay dry in the cold because moisture or dampness, e.g., from sweating, can increase the rate of heat loss from the body.
  • Keep extra clothing (including underwear!) handy in case you get wet and need to change.
  • Drink warm sweetened fluids (no alcohol).
  • Use proper engineering controls, safe work practices, and personal protective equipment (PPE) provided by your employer.

Check out the OSHA Winter Weather Guide. Stay safe and warm out there!