Employee Thermal (Heat) Stress
Safety Resources

What Is the AIHA Heat Stress Application?

The AIHA Heat Stress application is a mobile app (iPhone and Android) developed through a partnership by AIHA and East Carolina University intended for use in preventing heat related illnesses through recommended health measures for two specific user types. It is currently available for free download in the Google Play Android App store and Apple App store.

Our target users are:
1. Outdoor workers
2. Managers of outdoor workers

The key technical differentiator for this application is its focus on an adjusted Wet Bulb Globe Temperature (WBGT) calculation to inform risk and provided needed action steps. The WBGT calculation algorithm is the core mechanism powering our app's various functions.

To understand the importance WBGT and its use in monitoring heat stress, we recommend reading Joseph G. Allen's recent Washington Post editorial, "We need to change the way we think about outdoor temperatures. The public should adopt the 'wet-bulb globe temperature.'"

Learn More About AIHA's Heat Stress App

Follow the link relevant to your phone’s operating system below. Note that wherever a user is in the world, this link should open up their respective app store

To access the Heat Stress Application on Android:
ANDROID APP DOWNLOAD LINK

To access the Heat Stress Application on Apple iPhone:
APPLE APP DOWNLOAD LINK

*PLEASE NOTE: For Apple/iOS users: Anyone previously part of the open beta through iOS will need to redownload the app store variant to avoid the 90 Day Testflight expiration and to continue to receive the ongoing updates that we will be rolling out over time. Upon download, the test flight variant is automatically replaced with the app store version and will behave like all other applications a user has on their phone.

While every worker’s personal risk is different, the common denominator for all workers is that heat stress can strike nearly anyone in outdoor – and indoor – environments. Knowing the early warning signs of heat-related illness and ways to prevent it are important to staying safe and healthy no matter where you work.

Are You at Risk for Heat Stress Health Risks on the Job?

Nearly any workplace can present heat stress health risks for workers. Some workplace situations are obvious, such as a construction worker building homes in the sweltering summer heat; other workplaces are not as obvious, such as factories with poor ventilation that create a potentially hazardous situation. Occupational and environmental health and safety (OEHS) experts have identified the following industries as examples of work environments that pose the greatest heat stress risks for workers:

• Agriculture
• Construction
• Oil & Gas
• First responders/firefighters
• Utility companies
• Manufacturing plants
• Postal workers (Most OSHA-reported severe injuries)

It is also important to recognize the most common misconceptions about heat stress to fully understand your personal risk.

How to Protect Yourself From Heat Stress on the Job

Research has shown that in the United States alone, more than 700 heat-related fatalities occur on average per year, making exposure from environmental heat sources the country’s leading cause of weather-related deaths. Another analysis of the top causes of exertional injuries and fatalities examining OSHA data among laborers in the U.S. found that heat-related injuries accounted for 91.9% of the exertional injuries reported in OSHA’s Severe Injury Report database from 2015-2020.

So how can you protect yourself from heat stress on the job? OEHS experts offer these evidence-based tips:

• Hydrate
• Seek shade
• Rest with adequate breaks
• Use body cooling products
• Follow company-based guidelines
• Utilize environmental monitoring tools
• Self-pacing during work
• Slowly acclimatize to work environment in the heat

Understand Your Company’s Written Heat Stress Management Plan/Emergency Action Plan for Exertional Heat Stroke – and Practice It

Your worksite should have a comprehensive heat stress management plan to prevent heat-related illnesses and improve worker productivity. It is important for you to know, and to practice, the written policies and procedures. Examples of strategies in a heat stress management plan would include environmental monitoring (Wet bulb globe temperature), seeking shade, activity modifications or work-to-rest ratios, and body cooling accessibility. We know that not all prevention plans are fail-proof, and it is important to be aware of what to do if someone suffers from a heat illness. Make sure to understand your emergency procedures and know what your role would be in the event of a heat-related emergency.

Pace Yourself and Acclimate to Your Work Environment

Those who are working at higher physical workloads for prolonged periods of time are more susceptible to heat-related injuries and illnesses. It is important to pace yourself to ensure you take adequate rest breaks during your work shift. If you are new or returning from a prolonged work absence (at least 2 weeks), you should slowly and progressively adapt to your work environment again. This will allow you to achieve adaptations that will help you tolerate working in the heat. This process is called heat acclimation or heat acclimatization.

Know Your Personal Risk Factors

There are multiple personal risk factors that can increase your risk of heat-related injuries or illnesses. Some examples include:

• Sedentary Lifestyle (no physical fitness level)
• Previous heat illness
• Type 1 and 2 Diabetes 
• Hypertension
• Heart Disease
• Kidney Disease
• Older Age
• Dehydration
• Medications that affect thermoregulation, central nervous system function, sodium balance
• Obesity
• Poor sleep quantity and quality
• Illness (i.e., respiratory, infection, etc.)

If you arrive at work with the following symptoms or conditions, you are at greater risk of heat-related illness:

• Dehydration
• Lack of sleep
• Fatigue or lack of recovery from previous day
• Gastrointestinal discomfort
• Not recently eaten
• Psychological stress

Here are simple ways to determine your hydration status:

1. Assess your urine color

Pale yellow or “straw-colored” urine typically indicates that you are adequately hydrated. The darker the urine, the more at risk you are for dehydration.

How to Use a Urine Color Chart
(www.hydrationcheck.com)

2. Assess your Urine Output

More urine is typically produced when adequately hydrated and less urine is produced when dehydrated. Therefore, a reduction in daily urine frequency (how often you urinate) may be an indicator of dehydration. Urinating five times in a 24-hour period typically indicates you are adequately hydrated.

3. Pay Attention to Thirst

When in a dehydrated state and body water content is low, fluid regulatory mechanisms in the body will initiate sensation of thirst as a signal to consume more fluids. If you are thirsty, you are ALREADY dehydrated! It is important to note that the absence of thirst does not indicate the absence of dehydration.

Know the Signs and Symptoms of Exertional Heat Stroke

Exertional heat stroke is a serious medical condition caused by overheating of the body that requires immediate medical attention. OEHS experts share the following symptoms that are warning signs of exertional heat stroke:

• Body temperature of 104° or higher
• Confusion, agitation, irritability, disorientation, delirium
• Slurred speech or staggering
• Seizures, coma
• Sweaty skin or dry, hot skin
• Headache
• Dizziness or lightheadedness
• Nausea and/or vomiting
• Muscle weakness or cramps

When to Seek Help

Studies show that more than 700 heat-related fatalities occur on average every year in the U.S., making environmental heat exposure the leading cause of deaths due to weather. That’s why it’s important to seek help if you or a co-worker experience any of the symptoms of exertional heat illness.

Recognition and Treatment of Heat-Related Illnesses

Heat Syncope

• Fainting episode, normal body temperatures
• Signs and Symptoms: dizziness, weakness, tunnel vision, decreased or weak pulse, pale or sweaty skin, loss of consciousness
• Treatment: move patient to shade, sit or lie down patient when symptoms occur, monitor vital signs, elevate legs to promote blood returning to heart, rehydrate

Exercise-induced Muscle Cramps

• Painful, involuntary muscle spasms (usually occurring in legs) in the heat
• Prevention/Treatment: adequate fluid and electrolyte replacement, stretching of the muscle, rest

Exertional Heat Exhaustion (MOST COMMON)

• Signs and Symptoms: fatigue, nausea, fainting, weakness, vomiting, dizziness, pale, chills, diarrhea, irritability, headache, decreased muscle coordination
• Core temperature: usually between 102°-105°F
• Treatment: move to shaded area, cool patient (ice bags, ice towels, cooling vests, etc.), remove excess clothing, elevate legs to promote venous return, provide fluids and rehydrate

Exertional Heat Stroke (MEDICAL EMERGENCY)

The two main diagnostic criteria for EHS are:

• Core temperature greater than 104°-105°F (or 40°-40.5°C)
• Central nervous system dysfunction (altered consciousness)

If someone exhibits signs of exertional heat stroke, this is a medical emergency and medical professionals should be contacted immediately. This can include calling an on-site medical professional and calling 911.

Treatment: Aggressive, whole-body cooling with Cold Water Immersion (CWI). Until a medical professional is present, the individual must be aggressively cooled with water and ice to reduce their core body temperature. If core body temperature is NOT down to normal values within 30 minutes, they are at significant risk of long-term or permanent complications or death.

How to Talk to Your Employer About Heat Stress

Limiting heat stress in the workplace is beneficial not only to employees, but employers as well. Numerous studies show that productivity suffers when workers’ health is compromised by heat stress. If you feel that your working conditions are contributing to experiencing heat stress on the job, please talk to your supervisor about your concerns. Research confirms that implementing sound heat stress prevention strategies can both safeguard employee health and improve productivity:

• Studies estimated that when workers were performing work under the shade, there were 6- and 10-fold (respectively) increases in productivity.
• One study found that moving a working shift 2 hours earlier to avoid heat stress reduced costs by 33%.
• One multi-country study showed that workers picked 63% more crop when provided a heat stress prevention strategy (use of mechanical cart) compared to “business as usual”.