How to Understand the Heat Index: It’s the Heat. And the Humidity.

| BlackHawk Team

Summertime is especially hazardous for workers who toil outdoors or in high-heat environments. Heat causes a person to lose fluids through sweating, exertion and breathing. These fluids contain electrolytes which are necessary for proper cellular and muscular function. The four key electrolytes in the body are sodium, calcium, magnesium and potassium.

The Heat Index (see chart), also known as Apparent Temperature, measures the “feel” of the mix of humidity and air temperature on the human body. The relationship of humidity and temperature to the heat index is linear. As temperatures and humidity rise, so does the heat index. And vice versa.


The Dangers of Working in Summer Heat

For workers exposed to sun and heat, understanding the effects of the heat index on the body is critical. When temperatures rise, the body perspires to cool itself through evaporation. But as relative humidity rises, so does the moisture content in the air, which slows the rate of evaporation. We all know too well that when it’s hot and sticky, it’s harder to stay comfortable.

On the job, fluid loss can lead to drastic consequences ranging from sunburn and simple dehydration to cramping, heat exhaustion and heat stroke. If you feel dizzy, weak or nauseous, stop and call for help!

Knowing the signs of heat-related illness is crucial:

  • Abnormal thinking or behavior
  • Slurred speech
  • Seizures
  • Loss of consciousness 

If these signs are present, take these actions immediately: 

  1. Call 911 immediately
  2. Cool the worker right away with water or ice
  3. Stay with the worker until help arrives

(www.osha.gov/heat)

Advance hydration is the best safeguard against heat stress injuries. It’s important to hydrate at regular intervals because dehydration sneaks up without warning. Once you feel thirsty, it’s too late.

Staying Hydrated

For an adult man in moderate conditions, this means drinking 13 cups of water per day. For a woman, nine. Fluid consumption should increase when working in high temperatures above 90°F.

We mentioned the four electrolytes earlier. These chemicals conduct electricity when dissolved in water. They are vital electrical conductors within the body’s systems. They help to balance the amount of water in the body, balance its acid/base level, move nutrients into cells, remove waste from cells, enable muscular movement and ensure proper organ function.

Water alone does not replenish lost minerals. Electrolyte-based hydration beverages such as Gatorade and Sqwincher are specially formulated to restore electrolyte levels.

Other factors besides temperature and humidity can contribute to heat-related problems:

  • Direct sunlight exposure
  • Exertion
  • PPE gear
  • Air circulation
  • Machine/equipment heat
  • Your physical condition and age
  • Medical factors

Stress “heat awareness”. Exercise caution when temperatures exceed 90°F. Acclimate workers slowly to the conditions. Adjust shifts so as not to exhaust workers. Make sure PPE clothing is adequate but not excessive. And hydrate, hydrate, hydrate.

BlackHawk encourages our customers to adopt a Summer Wellness program for employees. Inform your people about the hazards of heat loss and the importance of hydration safety. Encourage them to drink up regularly. Ensure that they have adequate sun protection and cooling gear. Help them to stay safe on the job.