Work produces heat. Heat produces sweat. Sweat cools the body.

Regulating your body's temperature should be simple, right?

Unfortunately, it's more complicated than that, especially when you add PPE.

Workloads, PPE, and Heat Stress

When we do physical work, our bodies heat up. That's especially true if the work takes place in a hot environment, but it will happen in the cold, too.

(Learn about 4 Unexpected Working Environments That Lead to Dehydration.)

Safety professionals need to know how physically demanding the work is. Whether it's light, moderate, or heavy will factor into their assessment of the risk of heat stress from a particular task.

However, they need to account for more than just the demands of the work and the environment in which it's carried out. Safety professional need another formula to determine how much additional heat can be expected from the clothing and PPE the employee must wear.

For many jobs, multiple layers of non-woven clothing, vapor barrier fabrics, gloves, hard hat, hearing protection, and eye protection are not optional, no matter how hot the environment happens to be.

Doing the math isn't always fun or easy, but we're dealing with heat stress here and heat stress is dangerous. Exposure to the heat can result in:

  • Heat rash
  • Heat cramps
  • Heat syncope
  • Dehydration
  • Heat exhaustion
  • Heat stroke

Heat stroke is especially worrisome. Even when it's not fatal (though it certainly can be), symptoms can include erratic behavior, shivering, convulsions, and a body temperature exceeding 104ºF.

(Learn more in Summertime Roadwork and Heat Stroke.)

The American Conference of Governmental Industrial Hygienists (ACGIH) sets threshold limit values and provides a comprehensive flowchart for managing heat stress and strain:

Flowchart

Tools like this provide a process flow we can follow, but you still have to know the formula and the math – or the phone number of an industrial hygienist!

Determining the heat stress of a job before it starts is a must. That will allow you to put general controls in place, such as heat stress training, medial surveillance and monitoring if necessary, and heat alert programs.

You should also promote and facilitate heat stress hygiene practices, including:

  • Fluid replacement
  • Self-evaluation
  • Diet, lifestyle, and health status
  • Acclimation
  • Risk evaluation

(Find out Why You Should Always Let Your Workers Acclimate to the Heat.)

Fluid Replacement

Managing all of this is very detailed work, and you should put a special focus on fluid replacement, or hydration.

We lose a great deal of water from the body by sweating. The purpose of this is to facilitate evaporative cooling, where the sweat evaporating from the body lowers the body's temperature. According to the NSC's Fundamental of Industrial Hygiene (6th ed), an individual can lose up to six quarts of water in one day. That's approximately 13 pounds of fluid!

It's not just water that's lost through sweating, but also minerals like sodium and chloride, known collectively as electrolytes. Normally, the body will get enough of the minerals it needs through a standard diet:

  • Sodium: Pickled foods, cheese, table salt
  • Cloride: Table salt
  • Potassium: Fruits and vegetables, such as bananas, avocados, and sweet potatoes
  • Magnesium: Seeds and nuts
  • Calcium: Dairy products, fortified dairy alternatives, and green leafy vegetables

Ideally, eating well would be enough. However, even light work when saddled with heavy PPE can create so much perspiration and fluid loss that you might need to supplement with a beverage fortified with the right nutrients.

(Learn more about Electrolytes: What They Are and Why They Matter for On-the-Job Hydration.)

Replacing fluids and electrolytes is an absolute requirement, and it has to begin before the work gets so intense you feel that you need them.

Tips for Proper Hydration at Work

  • Start at home, before you leave for work. Drinking a pint of water per hour will help you meet your body's demands so you're fully hydrated by the time work begins.
  • Drink small quantities of water as frequently as you can. It's better to stay hydrated than to wait until you're thirsty, and drinking larger quantities all at once can create its own physical issues.
  • Check your urine color. Darker urine is a sign of possible dehydration.
  • Go to the bathroom whenever nature calls. Holding in your urine slows down your body's natural elimination system.
  • If your workload or work environment is causing you to sweat heavily, consider using a commercial beverage designed to replenish electrolytes.
  • If you can’t drink while working, make sure you replace fluids during rest breaks.
  • Don't skip meals. Breakfast, lunch, and supper all help your body stay hydrated and replenishes the electrolytes you lose throughout the day. Carrots, cucumbers, and apples make great snacks for hot days, since all of them have high water content.
  • Avoid excessive consumption of sodas, alcohol, and caffeinated drinks.
  • Salt tablets had been a hydration standby for a long time. If you decide to use them, make sure you take them as recommended to avoid complications.


Free Download: The Essential Hydration Safety Cheatsheet & Dry Erase Poster


Tips for Using PPE in Hot Working Environments

  • Whenever possible, wear lighter colored clothing in hot sunny weather. Dark clothing absorbs heat from sunlight faster than lighter colors do. This includes hard hats and head gear.
  • If you are in long sleeves and pants at work (most of us in industry are), wear fabrics that wick away or absorb sweat.
  • If you have to wear specific clothing (FR or chemical resistant), consider having two sets and changing them during a rest cycle, especially the inner set you wear next to the skin.
  • If you can, take a shower during your lunch break. This will help you cool off but also reduce your risk of heat rash. Dry yourself well before getting dressed and returning to work.
  • If you wear a hard hat, keeping your hair short will help you stay cool. If your hair is long, wearing it in a ponytail can keep the back of your neck cool.
  • Cooling headbands, cooling neckbands, and cool suits are PPE that can actually help you beat the heat instead of being beaten by it.
  • Choose gloves with liners that absorb or wick away sweat. Keep extra liners with you so that you can change them out for a dry pair during your shift.

Final Comments

The best way to keep cool is to have well-defined, documented, and enforced work-rest cycles plus proper hydration.

That means it's a safety professional's job to do the front-end work of supplying clean, potable drinking water for the work force. Personally, I've found that commercially prepared, bottled, single-serving products are an excellent way to encourage hydration and they are surprisingly cost-effective (just remember to recycle!)

Preparing electrolyte-boosting drinks from powders and concentrates is also easy to do.

As always, preventing heat stress and heat-related illnesses requires your due diligence. Be sure to consult with your workers as well as the manufacturers and distributors of hydration products and cooling PPE to find out what will work best for you and your employees.