Silent Killer Part 3: How to Stay Safe in Extreme Heat

As climate change continues to intensify, heatwaves are becoming more frequent and severe, posing significant health risks to individuals and communities. Understanding how to stay safe during these extreme temperatures is crucial for protecting against heat-related illnesses. This article explores essential tips and strategies to keep cool and safe when the mercury rises, ensuring you can navigate the challenges of a heatwave effectively.

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This is part 3 of a three-part explainer series on extreme heat. Read part 1 and part 2.

If you read the previous articles of our heat series, you will know that cities around the world rely on warning systems to inform their residents about the arrival of a heatwave and share recommendations. Understanding how these warning systems work and knowing when they are in place are essential steps in protecting yourself from excessive heat.

Below are some recommendations on how you can keep yourself informed:

• Follow local weather services: Check local meteorological services or news channels regularly, as they provide real-time updates and alerts about heat advisories and warnings. Local governments and emergency management agencies often post timely updates on social media platforms as well so keep them monitored.
• Use weather apps: Download reputable weather apps that provide notifications about extreme heat conditions. Many of these apps allow users to set alerts for specific weather events in their area.
• Sign up for emergency alerts: Many cities have rolled out local emergency notification systems or community alert programs that citizens can easily enroll in. These services often send text or email alerts directly to residents during extreme weather events, including heatwaves.

To offer protection to their citizens during extreme and prolonged heat events, local authorities can open temporary shelters and cooling centers. Knowing what your options are and where these places are located can be beneficial in situations where quick decision-making is crucial, such as during emergencies, travel planning, or when seeking essential services in unfamiliar areas.

By staying informed, residents can take proactive measures to protect their health and safety, including planning their activities, seeking shade, and ensuring proper hydration. Below are key rules and strategies that will keep you safe.

Tips to Stay Safe During a Heatwave

1. Hydration

In sweltering conditions, the human body dehydrates quickly, leading to symptoms such as fatigue, dizziness, and heat-related illnesses like heat exhaustion or heat stroke.

Dehydration is a consequence of sweating, the body’s natural cooling mechanism. Through sweat evaporation, skin and body cool down. However, this process also leads to a significant loss of fluids and electrolytes and a decrease in the volume of blood, 90% of which is water. When this occurs, the heart rate increases as a way to maintain adequate blood flow and oxygen delivery to vital organs.

This elevated heart rate can put additional strain on the cardiovascular system, increasing the risk of heat-related illnesses. Inadequate hydration can also reduce the heart’s efficiency, potentially leading to fatigue and a higher likelihood of heat exhaustion or heat stroke.

So, while keeping hydrated is always key for overall health, it is especially important in hot conditions.

Research suggests that a person should drink around two liters of water per day, or about eight glasses, during non-heatwave times. In heat conditions, the body needs more. Experts recommend drinking throughout the day and urinating around six to seven times a day, or every two to three hours. Pale urine is a good indicator of optimal hydration, while darker, strong-smelling urine in small amounts can be a sign that your body is dehydrated.

In its guidelines for outdoor workers working in the heat, the Centers for Disease Control and Prevention (CDC) recommends drinking one cup of water (approximately 8 onces or about 250 milliliters), every 15-20 minutes, as “drinking at shorter intervals is more effective than drinking large amounts infrequently.” At the same time, the agency discourages an hourly intake higher than 48 ounces (about 1.4 liters).

Similar tips apply to those who have been sweating from physical activity or from being unwell.

As for what to drink, water is by far the best way to replace lost fluids. By contrast, alcohol can cause dehydration. Experts also discourage drinks like tea, coffee, and energy drinks for a similar reason, besides the fact that they can increase heart rate and blood pressure in some individuals.

2. Nutrition

During a heatwave, appetite typically decreases. This has to do with the hypothalamus, a structure deep in your brain that acts as the body’s smart control coordinating center for both body temperature and hunger. When engaged in temperature regulation, the hypothalamus’s focus on hunger diminishes.

“[D]uring hot weather, our bodies naturally tend to eat less, as the hypothalamus prioritizes temperature control. It’s an important adaptive response to reduce heat production from digestion while managing body temperature,” explains Lizzy Davis, Assistant Professor and Dietitian Education Program Director at the University of Alabama at Birmingham’s Department of Nutrition Sciences.

But despite a lack of appetite, eating nutritious foods during a heatwave is almost as import as keeping hydrated. The World Health Organization (WHO) recommends eating small meals frequently throughout the day.

Experts recommend sticking to hydrating, fresh food, those that contain a high percentage of fluids and will thus best hydrate the body. Examples include watermelon, peaches, berries, grapes, and oranges, vegetables that can be juiced, such as spinach, cucumbers, olives, beets, and carrots as well as liquid meals such as soups.

Spicy food is known to make the body sweat as it activates heat receptors in the mouth. For this reason, expert advise against it when it is hot. Similarly, the unhealthy fats contained in fried food can increase the body temperature and they also require more energy to digest, potentially leading to discomfort, sluggishness, and further dehydration in hot conditions.

Experts also recommend avoiding cooking at home during a heatwave or opting for a microwave instead of an oven as a way to keep the environment cool.

3. Clothing

During a heatwave, choosing the right clothing is essential for comfort and health. Experts recommend lightweight, loose-fitting garments made from breathable fabrics such as cotton and linen. These materials allow sweat to evaporate more easily, helping to regulate body temperature. Remember: it is not sweat per se that cools the body down but rather the evaporation of that moisture from the skin. According to WHO guidelines, it is best to avoid synthetic fabrics as they trap heat and moisture.

A 2021 study published in Lancet observed that heatstrokes are commonly seen in otherwise healthy individuals and workers who engage in intense physical activity that generates significant heat. The authors found that this condition often occurs when clothing or equipment hinders the body’s ability to cool down, particularly in temperate to hot environments.

The debate surrounding the best clothing color during a heat event is more complicated. While it is widely accepted that light-colored clothes are a good choice because they reflect sunlight and reduce heat absorption, experts hold mixed opinions about dark fabrics.

Some argue that dark colors trap heat from the sun and are therefore not advisable. For instance, the International Federation of Red Cross and Red Crescent Societies recommends to “avoid dark colors since they absorb heat.” However, studies have shown that dark clothing can effectively radiate heat away from the body, allowing it to dissipate more efficiently than white clothing, which tends to reflect heat back.

This theory was supported by a 1980 study examining why Bedouins in the hot desert wear black robes. The study concluded that “the amount of heat gained by a Bedouin exposed to the hot desert is the same whether he wears a black or a white robe,” and that “the additional heat absorbed by the black robe was lost before it reached the skin.”

Additionally, layering can be beneficial, as it allows for adjustments based on changes in temperature throughout the day. Lightweight scarves can provide protection against sunburn while still being easy to remove. As a 2021 study states: “Removing or modifying clothing or protective equipment reduces resistance to sweat evaporation and convective heat exchange at skin surface.”

Whenever outdoors on a hot day, the WHO also recommends applying sunscreen as well as wearing a wide-brimmed hat and sunglasses to protect the skin from harmful UV rays, even on cloudy days.

4. Exercise

For those exercising outdoors, the CDC recommends doing so during the cooler parts of the day, particularly in the early morning and late evening. However, experts highlight that the urban heat island effect can complicate this guidance in cities.

Urban areas often retain heat due to materials like concrete and asphalt, which absorb warmth during the day and release it slowly at night. As a result, evening temperatures in cities can remain significantly higher than in rural areas, potentially making late workouts feel hotter than anticipated. Therefore, those exercising in urban environments should be mindful of this effect and consider alternative times or locations to ensure a safer and more comfortable exercise experience.

A 2021 study published in Lancet also recommends taking 5 to 10-minute breaks regularly, as they help reduce metabolic heat production sufficiently and thus lower the body’s temperature. Whenever possible, take breaks in the shade or indoors to allow your body to cool down faster.

The CDC also reinforces the importance of sensible attire during extreme heat: lightweight, loose-fitting clothing made of breathable fabrics, such as cotton, linen, bamboo, polyester, nylon and microfiber.

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Lighter exercises like walking, stretching, or yoga are preferred over strenuous and high intensity workouts. Warm-up and cool-down should not be neglected as they can help your body adjust more gradually to temperature changes.

Hydration, as mentioned above, is key. Experts recommend hydrating well before a workout and drinking throughout every 15-20 minutes, especially when the physical activity lasts longer than an hour. For prolonged or intense activities, consider sports drinks that replenish electrolytes lost through sweat. After your workout, continue to hydrate to help your body recover and cool down.

Understand the Symptoms and Act Accordingly

Taking all the precautions in the world may not always be sufficient, which is why it is crucial to understand how heat-related issues manifest.

Common signs include excessive sweating, weakness, dizziness, nausea, and confusion. Once you recognize the symptoms, do not ignore them. If you or someone else exhibits signs of heat exhaustion or heat stroke, take immediate action such as moving to a cooler location, hydrating, and resting or seek medical help.

Recognizing symptoms early can prevent serious health issues such as heat exhaustion and heatstroke and it is especially important for vulnerable populations, including the elderly, children, and those with preexisting health conditions. Keep an eye on elderly relatives, neighbors, or anyone who may be more susceptible to heat-related illnesses.

Below are some tips on how to lower the body temperature:

• Drink plenty of water throughout the day. Staying hydrated helps your body regulate temperature and prevents overheating
• Take a cool shower or a bath
• Apply cold packs or damp cloths or towel to pulse points, such as the wrists, neck, and forehead. This can provide immediate relief and help lower your body temperature.
• Utilize fans to increase air circulation. If possible, place a bowl of ice in front of a fan for a cooling breeze
• Practice deep breathing exercises, which can help calm your body and reduce the perception of heat
• Keep your home cool by closing the curtains during the hottest parts of the day and opening windows at night time

Featured image: Kyle Lam/hongkongfp.com.

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Read part 1 of our heat series, where we looks at how extreme heat affects the human body and what socio-economic and physiological factors play a role, and part 2, where we look at how cities are adapting to extreme heat.