Temperatures are soaring, records are being shattered and it can feel as if there is no relief in sight. From coast-to-coast heat domes to eponymous heatwaves like Cerberus, extreme heat events may be the new norm. And companies have more than one reason to be worried.
A 2021 Moody’s report identified heat stress as a physical risk that impacts almost every sector. Beyond rising cooling costs and shifting consumer demand, heat stress represents a major threat to companies because of its effects on human health. Heat waves can cause exhaustion, cramps, worsening mental health, diabetic complications, and even stroke. There is considerable risk in any population, and this includes your company’s workforce.
In addition to direct health costs of heat waves, the World Health Organization cites one of the most important economic impacts as lost productivity. Two percent of total working hours are projected to be lost each year due to heat stress at work, representing more than $4 trillion annually by 2030. So when 100 million Americans are under a heat alert, that could mean up to one in three employees – or more, depending on your company’s geography — are at risk at a given time.
Keeping your cool when extreme heat hits your workforce isn’t easy, but insights from health care can help. As a physician working for an international organization advising corporate leaders, I’m seeing employers looking to deepen their understanding of heat stress to adopt new best practices that safeguard their people and their business. Here are six actions to consider in navigating this challenge.
1. Take a preventative approach.
Employers should start by educating employees on what heat stress is, how it affects their health and safety, and how it can be prevented.
In any warm environment, the human body relies on its ability to get rid of excess heat to maintain a healthy internal body temperature. This happens naturally through sweating and increased blood flow to the skin. If this doesn’t happen quickly enough, body temperature rises and heat stress can occur.
Workers may experience symptoms including thirst, irritability, heat rash, heat exhaustion, or heat stroke which includes brain dysfunction such as slurred speech, confusion, disorientation or even coma. Heat stress can also impair fine motor skills, such as typing, and reduces capacity to process task-relevant information.
During heat waves, workers may experience a combination of two kinds of heat-related illness: “exertional heat illness” due to physical activity and “environmental heat illness” due to ambient conditions like heat and humidity. The latter is especially common in urban heat islands where temperatures in a city are much warmer than nearby rural areas.
Ultimately, heat stress can lead to illness, hospitalization, and even death. Given the potential severity, upstream solutions are critical. An effective heat-related illness prevention program should be incorporated in your organization’s broader health and safety program and align with the Occupational Safety and Health Administration’s (OSHA) recommended practices.
During the first few days in a heat wave, employers should encourage workers to hydrate, take frequent breaks, and quickly identify any heat-related symptoms.
2. Know how hot is too hot — and for whom.
Workplace heat exposure involves a combination of factors. To determine if heat stress is too high, employers need to assess the:
- Environment (including conditions such as humidity, sunlight, and airflow)
- Job (for example, whether it involves physical activity or protective gear)
- Worker (assessing common individual risk factors, such as age, pre-existing health conditions, and lifestyle)
The most accurate way to measure environmental heat impact on body temperature is with a wet bulb globe temperature (WBGT) meter, which incorporates temperature, humidity, sunlight, and air movement into a single measurement. OSHA provides guidance for use and interpretation of results. A heat index focused on temperature and humidity alone can provide helpful surrogate data in certain circumstances.
Job-related physical activity can be estimated using metabolic heat and workload tables with workload classified from light (e.g., sitting or standing) to very heavy (e.g., intense activity). Employers should also be aware of whether workers’ clothing increases risk and recognize jobs in hot environments such as firefighting, farming, construction work, mining, and factory work.
Individual worker factors can also indicate unique risks whereby different employees react to heat in different ways. This includes vulnerable populations, such as those who are 65 years of age or older, pregnant, have certain types of heart disease, high blood pressure, obesity, diabetes or use certain medications. Gender differences are important to consider as well. The National Institute for Occupational Safety and Health (NIOSH) reports several studies showing women are less heat tolerant than men.
3. Maximize indoor thermal comfort.
Thermal comfort for office work is important for well-being and productivity. Too warm, and employees feel fatigue or experience mood disturbance. Too cold, and attention can drift with employees feeling restless or distracted.
Maintain consistent thermal conditions in the office environment. Even minor deviation may cause stress and affect performance and safety. Workers already under stress are less tolerant of uncomfortable conditions, so temperature becomes particularly important for high-demand jobs and during periods of high-stress crisis response.
Optimize temperature to match recommended guidelines. The American Society of Heating, Refrigerating, and Air Conditioning Engineers (ASHRAE) Standard recommends temperature ranges of 68.5°F to 75°F in the winter, and 75°F to 80.5°F in the summer. The difference in seasonal temperature ranges is largely due to clothing selection.
In some situations, legislation may have specific requirements and it is important for employers to meet these. Beyond federal OSHA standards, some states have adopted OSHA-approved state plans that cover hazards not otherwise addressed. For example, Minnesota regulates indoor air temperatures in places of employment and varies requirements based on intensity level of work. Similarly, Oregon recently adopted some of America’s most protective heat rules for workers.
Recommended temperature ranges meet the needs of at least 80% of individuals but some employees may feel uncomfortable even if these values are met. Temperature needs and preferences vary greatly, and there is no one temperature that can satisfy everyone. Additional measures may be required.
Difference in thermal comfort may be due to indoor climate regulations being based on standard values in men and can impact women’s cognitive performance. In general, women prefer higher ambient temperature at home and in the workplace. That being said, when it comes to heat waves, women are generally more vulnerable to high temperatures. And this vulnerability increases after menopause when lack of estrogen production makes it more difficult to adapt to sudden temperature increases.
Given thermal comfort is determined by a number of factors beyond temperature, such as activity levels, solar gain, and air flow, optimizing for those can help. For example, enhance access to desk fans or working areas of greater air flow for menopausal women experiencing hot flashes. Other options to make the workplace more comfortable include changes to workload and schedules. For example, scheduling work during off-peak temperature hours or shorter shifts with frequent rest breaks.
4. Tailor training and safety for outdoor workers.
Provide a heat stress training program before hot outdoor work begins. Training may include proper use of heat-protective clothing and equipment, effects of drugs and alcohol on heat stress tolerance, immediate reporting of signs or symptoms of heat-related illness (in oneself or coworkers), and procedures for responding to these symptoms.
Supervisors should be provided with additional training. This may include monitoring alert reports, responding to hot weather advisories, procedures to follow when a worker has signs or symptoms of heat-related illness (including contacting emergency medical services where appropriate), encouraging hydration, and reinforcing rest breaks.
Beyond training, employers should reduce workplace heat stress using engineering and administrative controls. Engineering controls include changes to work-setting design that reduce exposure to heat, such as the use of reflective or heat-absorbing shielding. Administrative controls are changes to tasks or schedules that reduce heat stress, for example, limiting time in the heat, increasing recovery time in cool shaded areas, increasing the number of workers per task, or providing adequate cool, potable water. It is also important to limit heat burden while wearing personal protective equipment (PPE) and to explore auxiliary cooling systems, like water-cooled garments or cooling vests.
Additional strategies include creating a multi-disciplinary working group (e.g., cohort of workers, qualified health care provider, safety manager), instituting medical and self-monitoring programs, wearable monitors to estimate workload (e.g., heart rate sensors), and a buddy system where workers observe each other for signs of heat-related illness.
5. Practice acclimatization.
Individuals can adapt to higher temperatures through repeated exposures, for example, via increased sweating efficiency. This is particularly relevant for outdoor workers during rapid onset heat waves.
Employers should develop acclimatization schedules in hot conditions that gradually increase worker exposure time and physical demands. This is typically done in a step-wise process over a seven to 14 day period. New workers will need more time to acclimatize than those with pre-existing exposure, and absence for a week or more may require re-acclimatization.
The level of adaptation for each worker is relative to physical fitness and heat stress experienced. It is also important to consider gender differences, as women require greater intensity, frequency, and duration of heat exposure for adaptation. Given related literature primarily focuses on males, current guidelines may not account for physiological differences and may require employers to explore new frameworks.
6. Adopt a long-term heat-health action plan
As extreme heat continues to worsen, employers must adopt a long-term approach. The World Health Organization’s guidance for heat-health action plans offers particularly useful principles.
Similar to how airlines track weather for flight planning, employers should tap into accurate and timely temperature alert systems that trigger weather-related warnings, determine thresholds for action, and communicate risks. Establishing links with local public health systems and emergency response services also helps.
You should also have a communication plan that includes what to communicate, to whom, and when. Recognize that you may be managing multiple environmental health issues simultaneously — for example, extreme heat and air quality issues related to wildfires — and be sure to streamline messaging. Avoid overwhelming employees with multiple non-synchronized communications. Also tailor your messaging for local areas.
Your heat-health action plan should also include short and medium-term heat relief approaches, such as reduction in indoor heat exposure, enhanced outdoor worker protections, and a care strategy for vulnerable populations. Your long-term approach should include strategic urban planning to address building design, location, and transit access points that can reduce heat exposure for employees in their end-to-end journey from home to work and back.
Track efficacy of your heat-health strategy over time. Implement real-time surveillance and evaluation particularly for outdoor workers, and don’t forget oversight of indoor environment controls. Monitor for quality and consistency to make sure you are meeting ASHRAE recommendations and local legislation requirements. Engaging safety checklists and standard best practices found in the airline industry can be especially helpful.
Extreme heat can greatly impair the performance and health of your greatest assets — your people. As these high temperatures become more commonplace, employers must seize the opportunity to protect their employees today and into the future.