Is it too hot to work? Heat stroke and heat exhaustion. What you need to know.

When Is It Too Hot To Work?

Heatwaves are becoming more frequent and intense, setting new records worldwide. Extreme heat is deadlier than hurricanes, floods, and tornadoes combined. Whether you work outdoors or in a hot environment like a steel mill, kitchen, bakery, or an unairconditioned office, it’s crucial to understand when it’s too hot to work and how to protect yourself. In this blog post, we’ll provide friendly and informative guidance to help you stay safe and beat the heat.

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Understanding Heat-Related Risks

Your body constantly works to maintain a core temperature of around 37 degrees Celsius (98.6 degrees Fahrenheit), even during heat waves. If your body temperature rises too high, it can lead to heat exhaustion or heat stroke. Sweating is a primary way your body cools itself, but excessive humidity can hinder sweat evaporation, increasing the risk of overheating. Age, fitness level, underlying medical conditions, and individual heat tolerance influence your susceptibility to heat stress.

One of the main ways the body cools itself is through the evaporation of sweat.  You can quickly overheat if your sweat cannot evaporate because of the large amount of moisture in the air (humidity).  That is why the humidity of the air is so important when discussing heat stress. With a high humidity the temperature will feel much higher than the thermometer indicates.

Exposure to heat and to toxic chemicals at the same time is extremely challenging for the body. Make sure you know how to work with the toxic chemicals at your work by taking the Free WHMIS training or the Free Hazard Communication Standard Training

Take Frequent Breaks and Acclimate

 You are most likely to get heat stroke when you are exposed to a sudden increase in temperature, such as during an early-summer heat wave or travel to a hotter climate. Most occupational heat-related deaths occur in the first 1-3 days of working in the heat. Even if you recover from heat stroke, you may have long-term damage to your heart and nervous system.

It’s important to ease into working in a heatwave and allow your body time to acclimate to the conditions. Acclimatization, which can take several weeks, enables your body to adjust gradually and cope better with the heat. Remember, taking it easy initially is crucial to your well-being.

Warning Signs and Symptoms of Heat Exhaustion and Heat Stroke

  • Muscle cramps
  • Heavy sweating
  • Weakness or tiredness
  • Dizziness
  • Headache
  • Confusion
  • Fainting

Stay Hydrated and Check Air Quality

Drinking plenty of water while working and even during off-hours is essential to maintain proper hydration and replenish fluids. Additionally, be cautious when working in hot environments with poor air quality due to factors like wildfires or pollution. Keep an eye on air quality advisories and take necessary precautions to protect your health. Check out the health effects of wildfire smoke and how to protect yourself.

Measuring Your Heat Risk

A simple method to assess your heat risk is by monitoring your heart rate. If your heart rate remains consistently above the value obtained by subtracting your age from 180 for several minutes, it indicates an increased risk of heat illness. Investing in a smartwatch that monitors heart rate can be beneficial.

If you work in the heat, get a smartwatch. Watches that measure your heart rate are readily available and inexpensive. Soon your smartwatch will be able to tell you when you are at risk of heat stroke, but until then, keep it simple.

Know Your Rights and the Regulations In Your Area

Various countries, states, and provinces have different legislative requirements concerning work in the heat. It is crucial to familiarize yourself with the regulations specific to your jurisdiction. In the United States, Europe, and Canada, employers are generally obligated to take reasonable precautions for worker safety. Workers have the right to refuse unsafe work and should communicate any feelings of faintness, lightheadedness, coordination issues, or illness to their supervisor. Checking on co-workers’ well-being is also encouraged, as they may require assistance.

Guidelines and Regulations for Heat Exposure

The legislative requirements regarding work in the heat vary by Country, State and Province. Some Jurisdictions have no maximum heat exposure limits beyond the legal obligation to keep workers safe, in contrast, such as California, Minnesota, Oregon, Washington, and British Columbia, Canada, have specific regulations. The province of Ontario is proposing a new stand-alone Heat Stress Regulation.

For example, California’s Heat Illness Prevention Standard for outdoor work requires employers to provide training, water, rest, shade, and planning. A temperature of 80°F triggers the requirements. At 95°F, more stringent requirements kick in. For indoor places of employment, the regulation will apply where the temperature reaches 82°F.

In Oregon, the Heat Illness Prevention Standard applies at a heat Index of 80°F. At a heat index of 90°F, more rigorous requirements kick in.

“The Heat Index sometimes referred to as the apparent temperature or “feels like,” is given in degrees Fahrenheit and is a measure of how hot it really feels when relative humidity is factored in with the actual air temperature.”

The National Weather Service

The National Weather Service uses a heat index (HI) to classify environmental heat into four categories: Caution (80°F – 90°F HI), Extreme Caution (91°F – 103°F HI), Danger (103°F – 124°F HI), and Extreme Danger (126°F or higher HI).

The Wet Bulb Globe Temperature (WBGT) is considered a more accurate indicator of the effects of heat on individuals than just the temperature or Heat Index (HI). Wet Bulb Globe Temperature is a measure of the heat stress in direct sunlight, which takes into account: temperature, humidity, wind speed, sun angle and cloud cover (solar radiation).

See the chart below from the National Weather Service for some basic working guidelines using the WBGT.

Heat stress and wbgt from the National Weather Service
WBGT Heat Risk and Impacts From the National Weather Service

The National Institute for Occupational Safety and Health (NIOSH) has set out guidelines using the WBGT. The guidelines incorporate how much of each hour is worked (15 minutes per hour to 60 min./h.) and how hard the person is working (100 to 500 Kcal/h).

Recommended heat stress alert limits from NIOSH

In Ontario, Canada, a more straightforward method using the Humidex scale has been developed, which combines temperature and humidity to determine perceived temperature. Any Humidex level above 30 may cause discomfort for healthy adults, while levels above 35 require a hot weather plan. Above 40, all unnecessary activity should cease.

See the Occupational Health Clinics for Ontario Workers for a great humidex calculator that gives some basic safety measures to follow when the temperature gets hot.

Although it is not used in any regulations for heat exposure you may also see the “Feels Like” temperature on the News or your Weather app.
“Feels Like” temperature includes the effects of humidity and wind speed to adjust the actual temperature to help us understand how it feels outside. It’s a way to express the overall temperature sensation you experience on your skin when you step out.

If You or Someone Else Feels Sick From the Heat

If you or someone else experiences heat-related illness, acting quickly is crucial. You want to get the body temperature down as quickly as possible. Use as many of the methods listed below as you can.

  • Move out of the heat to a cool area
  • Place hands and forearms in cool water
  • Place cool wet towels or ice packs on the armpits and groin
  • Spray with a garden hose or take a cool bath or shower
  • Give cool liquids, but if the person is confused or unconscious, the drinking of liquids is not recommended

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Keep you and your family safe. Ensure everyone knows the signs and symptoms of heat exhaustion and heat stroke and how to keep cool. It takes less than 30 minutes!

Free heat stroke prevention training topics.

If you work outside in the heat, you may also be exposed to the cold in the winter. Check out “When Is It Too Cold to Work.”

If you want more information on heat exhaustion and heat stroke, please visit the websites below.

How do you keep cool when the heat is high?  Let us know.

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