Extreme heat
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The problem
An increase in frequency, intensity, duration and severity of extreme heat, including during heatwaves, is exposing vulnerable populations to greater heat stress. This contributes to significant negative health outcomes, particularly for infants, children, pregnant women, the elderly, outdoor workers and other vulnerable people.
For infants, young children and pregnant women, greater heat stress increases the chance of negative birth outcomes, chronic health issues and infant deaths.
559
million
children are currently experiencing high heatwave frequency globally.
Introduction to heat stress and actions to take
Children's unique vulnerability
About 559 million children are already exposed to high heatwave frequency and around 624 million children are exposed to one of three other high heat measures: duration, severity, or extreme temperature. By 2050, virtually every child on earth – over 2 billion – is forecast to face more frequent heatwaves, even if nations are on track to cap temperature increase to below 2 degrees Celsius, as agreed in the 2015 Paris Agreement.
Exposure to extreme heat can be particularly life-threatening to infants and young children because of their unique physiological and behavioural vulnerabilities. For instance, infants and young children have:
- Higher heat production: Because they have more internal heat to begin with and move less economically per given activity, children produce more heat per kilogram of weight than adults do.
- Greater body surface area: Younger children have a higher surface-area-to-mass ratio. This can lead them to absorb more heat from the environment, depending on their body and fitness levels. Conversely, this may be useful for heat dissipation in other environments.
- Lower levels of sweat production: Children have a lower rate of sweating than adults do because of a lower sweat rate per gland, and they begin sweating at a higher body temperature.
- Under-developed bodily systems: Infants experiencing heat stress are likely less capable of fighting off the symptoms, as they have under-developed sweat glands and less capacity for regulating their temperature independently. Their immune system is still developing, which potentially further diminishes their capability.
- Possible cellular modifications: When pregnant women experience heat stress, the stress placed on the fetus could affect its ability to synthesize proteins properly, by affecting heat shock protein development, it could leave the child more vulnerable to developing congenital defects and illnesses.
- Slower adjustment to changes in weather: Infants and young children adapt more slowly to changes in temperature than adults, partly because they have poorer blood circulation and lower proportional cardiac output.
- Poorer practice of fluid replenishment: If not appropriately supervised, children are more likely to inadequately replenish fluid loss during prolonged exercise.
Health impacts on children
Health outcomes in pregnant women, infants and children:
- The odds of preterm and stillbirth increase proportionately with exposure to increased temperatures.
- Newborns have a greater risk of being born with various congenital defects, including congenital heart defects, spina bifida and cranio-facial defects.
- Infants could get jaundice, neurological dysfunction, dehydration and potentially have an increased risk of sudden infant death syndrome (SIDS).
- Studies find that infants are breastfed for shorter periods during the hottest days of the year compared to the coldest, which can affect infant nutritional status and health. In addition, stunting and wasting can be directly linked to extreme heat exposure.
- Fetuses whose mothers are exposed to extreme heat are at higher risk of developing congenital defects, cardiovascular diseases, neurological dysfunction and cognitive development issues.
- Pregnant women who are exposed to extreme heat are more likely to be hospitalized during their second and third trimesters.
- There is a higher risk in pregnant women of pre-eclampsia and gestation hypertension, as well as gestational diabetes.
Protecting children from heat stress: a technical note
This note aims to improve the understanding of how heat stress impacts pregnant women, infants, children and adolescents; identify the symptoms of heat stress; and suggest interventions to support prevention, diagnosis, care and treatment to protect children’s health and well-being. It includes a risk communication framework, clinical case management and recommendations for planning and preparedness to protect pregnant women, infants, children and adolescents from heat stress.
Globally, over 1 billion children live in countries that are at ‘extremely high-risk’ from the impacts of climate change. This means half the world’s children could suffer irreparable harm as our planet continues to warm. Heatwaves, for example, are becoming longer, stronger and more frequent.
Catherine Russell, Executive Director, UNICEF
Tips for caregivers
Heat waves are anything but fun in the sun. Extreme heat and humidity can be extremely uncomfortable and pose serious health risks, especially for infants, children, pregnant women and the elderly. Without taking the proper precautions, extreme heat can lead to heat stroke and even worse, fatality. As a result of climate change, heatwaves are becoming longer, more frequent and more severe.
Here are some tips to help keep your family safe during a heatwave, how to recognize signs of heat stroke and what actions you should take if needed to "B.E.A.T. the Heat."
What partners can do
Prioritize strengthening the primary health care response to protect child health
in national development agendas, health action plans and climate commitments.
Institute national multi-sectoral early warning and notification systems
that will alert communities of upcoming heatwaves through multiple communication channels, with extra attention provided to vulnerable areas.
Promote cooperation
to improve cross-learning of best practices across countries and quickly scale-up the most impactful solutions.
Assign adequate financing to preparedness and response measures
as well as investing in built environments that provide ventilation and green spaces.
Advocate with decision-makers
including members of local governments, community leaders, school boards and others, on heat stress risks and ways to mitigate the health effects on children.
Implement a comprehensive
‘B.E.A.T. the Heat’ risk communication framework to strengthen the capacities of caregivers and frontline workers to recognize and address heat stress in infants, children and pregnant women.
Prioritize research
on the effects of heat stress on maternal and child health, as well as potential treatment, prevention and management to bring more attention to the issue.
Build the capacities of teachers and students by institutionalizing climate and health education
to support identifying the symptoms of heat stress and minimize adverse health risks as soon as possible.
Create new business opportunities
offering green technology and green services to consumers, including cooling, improved food security and energy-efficient building materials.
Advocate with governments
to create more liveable city and town spaces, including improving regulations for construction, transport and agriculture.
Support the health sector
in amplifying risk communication campaign messaging on staying safe during extreme heat periods, and implementing necessary protections for employees, particularly those who are more vulnerable such as children, pregnant women and the elderly.
Support the education sector
in accessing resources, like electricity, to protect students from heat stress during the school year, including for cooling, shade and clean drinking water.
Invest in existing adaptation financing mechanisms
to support interventions for primary health care, such as for providing necessary supplies and capacities, and building green spaces, particularly in urban heat islands and settlements.
