Summer is coming and along with it, the busiest season for construction. “During summertime, the effects of heat and humidity on the body need to be taken seriously” says Walter Jones, LHSFNA Occupational Safety and Health Division Associate Director. “While striving for optimum performance during this peak season, contractors and Laborers should pay special attention to preventing heat stress on the job.”

In the construction industry, most of the work is outdoors on sites and in work zones where there is no protection from the sun or where work conditions are extremely hot. For Laborers, working outdoors carries the risk of heat stress from prolonged exposure to stifling heat and humidity.

The effects of heat stress range from simple discomfort to dehydration, heat exhaustion and life-threatening heat stroke. Too much heat can cause fatigue, hurt job performance and increase the chance of injury. Heat stress also makes it difficult to concentrate on the job, which can be hazardous.


Symptoms of dehydration may include headaches, decreased blood pressure (hypotension) and dizziness or fainting. Dehydration symptoms generally become noticeable after two percent of normal water volume has been lost. Typically, thirst does not occur in the early stages of dehydration. Therefore, in hot, humid weather it is important to consume water, even if you’re not thirsty.

To counter dehydration, it is necessary to replenish water and electrolytes. Otherwise, cramps and more serious conditions can develop.

Heat Cramps

Heat cramps are muscle spasms, usually in the hamstring or calf muscles but also in the arms and abdomen. Often, they occur at break time when work stops. These contractions are forceful and painful. They usually improve with rest, rehydration and a cool environment.

Heat Exhaustion

Heat exhaustion is a result of excessive heat and dehydration. The signs of heat exhaustion include paleness, dizziness, nausea, vomiting, fainting and a moderately increased body temperature (101-102 degrees F) which, in this case, is not truly a fever but is caused by the heat. Rest and water will help in mild heat exhaustion. More severe exhaustion may require intravenous fluids, especially if vomiting keeps victims from drinking enough to rehydrate themselves.

Heat stroke

Heat stroke is becoming more common. A person suffering from heat stroke will stop sweating, and his or her body temperature will reach 102 degrees or more. The skin will be hot and dry. Confusion and loss of consciousness may occur.

Heat stroke is life threatening, and urgent treatment by a doctor is needed. While waiting for medical help to arrive, cool the patient as quickly as possible. Soaking the person’s clothes with cold water and increasing air movement by fanning can do this. If the person is conscious, give sips of cool water (not ice cold) to drink.

Risk of heat stress

An individual’s risk depends on certain factors, starting with the conditioning of his or her body. As long as blood is flowing properly to the skin, extra heat from the core of the body is “pumped” to the skin and removed by sweat evaporation. High humidity makes it harder for sweat to evaporate. Thus, the danger is greater on muggy days than on dry ones.

Overexertion and duration of exposure are also important risk factors in hot weather environments. Be aware of the surroundings.

The clothing you wear makes a difference as well. Light, breathable fabrics are preferred, whenever practical. The lighter the clothing, the easier to cool off.

Protect yourself

  • Replenish fluids throughout the day, at least eight ounces of water per hour.
  • Take rest breaks in a cool, shady spot and use fans when possible.
  • Wear light-colored clothing made of cotton.
  • A new job in a warm area requires time to adjust. Be extra careful the first couple of weeks.
  • Working with heavy, personal protective equipment (PPE) requires more frequent rest breaks.

Contractor obligations

OSHA does not have a special rule for heat. Since heat stress is known as a serious hazard, protection of workers is required under the General Duty Clause of the Occupational Safety and Health Act. The clause says employers must provide “employment free from recognized hazards, causing or likely to cause physical harm.”

If possible, contractors should plan to do the heaviest work at the coolest time of the day, even alternating work crews for the extra heavy jobs. Also, plenty of fluids and more rest breaks should be provided.