How maps can protect children from extreme heat

Heatwaves claim tens of thousands of lives each year. Now a US mapping project is revealing those most at risk so they can get the help they need.

On a hot evening in August, when temperatures in Irving, a suburb in Dallas, Texas, can reach a stifling 45C (113F), outdoor pursuits and an active lifestyle can often be challenging for Christina and Landon Howard and their two young children, aged nine and 10.

"We can't go swimming or take part in other daily outdoor activities because it's just too hot outside," says Christina."Our son had to came back indoors the other day after 10 minutes of skateboarding because he felt exhausted by the extreme heat conditions."

Children are at higher risk of being hospitalised during heatwaves when temperatures exceed 29C (84F), a study on heat and children's visits to emergency departments in New York City found. Children aged 0 to four were the most vulnerable, followed by children aged 13 to 18 and five to 12. 

Texan homes generally have in-built AC systems, but with little respite outdoors in the city heat, the increase in energy demand is an economic factor that the Howards are also finding burdensome.

"We're expecting to pay almost $1,000 (£787) for next month's electricity bill. This is already very alarming," says Landon."There's a higher potential of having to fork out money for costly AC repairs that are going to be even more difficult for us to pay."

Christina and Landon have decided to take matters into her own hands. In August 2023,they started volunteering with the National Oceanic and Atmospheric Administration (NOAA) urban heat island mapping campaign  after hearing of the scheme through a volunteer callout from the City of Dallas. The initiative collects hyperlocal data to understand vulnerabilities to heat exposure. For several years, Christina and Landon have also been part of a climate change focus group in Texas, helping to make this hidden heat crisis more visible.

"We have always been interested in how climate change will affect our lives and the world, even before recycling was a thing in Texas!" says Christina.

NOAA's heat maps are helping policy makers and families understand the real-life impact of heat waves with unprecedented clarity, by combining satellite imagery, air temperature and humidity data collected by volunteers, and enabling them to implement cooling solutions targeted at each community's specific needs.

"If community heat maps can help lobby governments in the US to recognise the long-term health threats of extreme heat, and the nuanced environmental and economic effects to protect our children and other families – we want to be a part of that," says Landon.

The Howard family are not the only ones who are experiencing the challenges of extreme heat.

As global temperatures continue to rise, extreme heatwaves have become increasingly common in cities around the world. Heatwaves are also projected to cause 38,000 worldwide deaths per year by 2050, with 1,300 deaths already happening each year in the US. The majority of these deaths occur in children under the age of five and adults over 65 years old, according to a report by the World Health Organization.

"We call extreme heat a 'silent killer', [as] we might not see the impacts right away," says Morgan Zabow, climate and health communication and outreach coordinator of the National Integrated Heat Health Information System  - a US organisation that provides awareness and science-based information to protect people from heatwaves.

Heat can also worsen pre-existing medical conditions such as respiratory and cardiovascular conditions in young children. "Heatwaves pose a greater risk to otherwise healthy children. They are less able than adults to regulate their body temperature, they sweat less, and their heart and breathing rates are faster than adults," says Kimberley O'Sullivan, senior housing and health researcher at the University of Otago in New Zealand.

Babies and children living in poorer neighbourhoods are among the most vulnerable to rising heat, and those belonging to ethnic minority groups.

The health risks can start even before children are born – and the impact can extend beyond their childhood.

One study that examined the impacts of exposure to extreme temperatures in New York City found babies born in temperatures above 29C (85F) and from lower socioeconomic backgrounds tend to have a reduction of 1.8g in birth weight, which is projected to increase to 4.6g by 2070.

Heatwaves, like other extreme weather events, exacerbate the divide between wealthy, often white communities in the US, and their economically disadvantaged or ethnic minority neighbours. 

"One reason for this is that a lot of people living in hot inner-city neighbourhoods, known as 'urban heat islands', are not prepared for the heat," says Nicole Ngo, lead author of the study and associate researcher in planning and public policy at the University of Oregon. Urban heat islands are dense areas with fewer trees, more buildings and black asphalt from sidewalks that absorb heat. They can be up to 6.7C (12F) hotter in the evenings than nearby areas which have more trees, grass and less black asphalt, according to the US Environmental Protection Agency.

The now-illegal practice of redlining, when federal governments labelled non-white neighbourhoods as undesirable, has historically influenced how much local funding has gone to these areas. Lower income families and communities of colour are more likely to reside in more densely populated areas, with closer proximity to polluting industries such as energy, construction and transport. And a growing body of research suggests that life in these areas is especially tough for children.But does this mean that people living in these areas don't want to take action?

"There is a negative assumption that poorer families are so pre-occupied with economic and social issues that climate change wouldn’t be of interest to them," says Merill Singer, professor of anthropology at the University of Connecticut in the US, whose research focuses on the community impact and perceptions of climate change in medical anthropology.

One study of a neighbourhood in Hartford, Connecticut, home to a large Latinx population, found that residents feel excluded from climate change information. Participants were very interested in how heatwaves were affecting the health of their babies and young children.

"We found in our research that residents were very concerned because they were already feeling the impacts and suffering the consequences," says Singer. "They want more information and want to participate."

Heat maps are emerging as a powerful tool to help vulnerable communities access this information and provide valuable insights into temperature patterns and locate hotspots. This is enabling policy makers to make better decisions about ways to reduce the impact of rising temperatures.

NOAA and its science partner, Capa Strategies, have been mapping more than 70 communities across 22 US states to identify where the hottest neighbourhoods are, why they are hotter than others, and how this affects people living there. They have been working with citizen scientist volunteers who often already reside in a vulnerable area or have an interest in climate change. Since launching the project in 2017, NOAA has recruited more than 20,000 community volunteers. The project gathered more than one million measurements in 2022.

Heat data is collected by the volunteers and is then used to aid federal governments to implement cooling solutions in each city through urban greening initiatives, daylighting streams – the process of uncovering buried waterways and restoring them to provide environmental benefits - as well as  building efficiency projects and cooling stations.

Led by a team of local community leaders, the volunteers use heat sensors mounted on their own cars to record temperatures on the hottest days of the year. This project is different to other federal heat mapping initiatives because it is a community effort, enabling residents who may not have had access to heat information before. Although previous mapping studies have measured land surface temperatures, NOAA follows a different approach to its data by looking at air temperature and humidity. "Land surface measurements are useful in some circumstances, when monitoring weather and climate patterns, for example, but they give a less accurate picture of the heat that people experience every day, namely air surface temperatures," says Zabow.

"Our urban heat map data is far more accurate to quantify the human experience when talking about the impact of heat on people," she adds.

The mapping project aims to share awareness about how to protect children from extreme heat and empower others who have an interest in tackling climate change.

"It's not just about government officials going into a city, taking measurements, and never speaking to them again," says Zabow. "It's people from these communities collecting data, who become volunteers and are passionate about learning about the impact heat is having on their children and their neighbourhoods."

The Howard family are an example of how local people can benefit from getting involved in heat awareness initiatives.

"We had a fun family day out in our car with our children – even though it was the hottest time of the day when we were collecting data," says Christina. "Through this experience and working with the City of Dallas and NOAA, we learned how to identify symptoms of heat-related illnesses and where to find resources online and in our community about ways to protect our children during heatwaves.

"We check in with our children more often to see if they are hydrated, and we've introduced more indoor play like board games and creative activities, like baking and writing stories, to motivate our children if outside play is limited when it is too hot outside," she says.

"Volunteering gave us a better understanding of how the environment plays its role in the impact of heat around us," says Landon. "Our data readings were noticeably cooler in neighbourhoods with more green space and trees, than those in more built-up areas."

Once the data is collected by the volunteers, it is stored in NOAA's Environmental Visualisation lab in Maryland, and is combined with census data from the White House Climate and Economic Justice Screening Tool, which identifies communities that are marginalised and overburdened by pollution. This is then aggregated through an interactive dashboard to prompt federal agencies to investigate how disadvantaged communities are being exposed to higher temperatures.

The dashboard shows the disparity of health risk between those living in low-income communities or minority groups and more affluent white neighbourhoods. Federal agencies signed up to the programme can use this data to implement strategies to make heat information and resources more accessible in their city, and plan bigger housing and urban development initiatives, such as the introduction of 100 new shaded bus stop shelters in Las Vegas by the Regional Transportation Commission, with plans to expand to 80% of neighbourhoods where some of the hottest readings are.

Zabow says the heat maps are making local decision makers pay closer attention to heat issues in their communities and implement effective cooling solutions.

"South Carolina recently declared a heat safety awareness week and we're seeing first-hand how this is positively impacting local neighbourhoods there. They are using our heat island data to build urban farms and a new energy efficient hospital in Charleston," she says.

Urban agriculture can help reduce temperatures by offering shade and cooling. Increasing urban greening, by for example introducing urban farms, can lower night-time temperatures by 1.1C (2F) in surrounding areas.

The upgraded Medical University of South Carolina hospital has increased the energy efficiency of its buildings by replacing old boiler controls and sensors, retrofitting water fixtures and fume hoods and installing LED lighting upgrades. The renewable energy developer of the hospital, Ameresco, has projected an annual carbon reduction of 3,223 tonnes and annual energy savings of $2,839,000 (£2,275,000).

Dallas is the seventh hottest city in the USA according to the Texas Trees Foundation - a non-profit organisation that aims to improve green spaces and plant trees in urban areas. The foundation is combatting extreme heat and heat inequality using existing data from their urban heat island management study. It has set a target to protect and increase Dallas' tree canopy from 32% to 37% by 2040, totalling to almost 15 million trees in the city. In 2015, the Texas Trees Foundation launched a 'cool schools' programme to plant more trees in lower income neighbourhoods, with the aim of providing at least a minimum of 27% shading and cooling relief. The programme has been an effective education effort and it has seen 300-500 children volunteers from each school participate in planting trees. To date the volunteers have planted over 2,000 trees around their school campuses.

The Texas Green Schools project in Houston has used heat watch mapping data to introduce a programme aimed at reducing energy consumption in schools and increasing access to green spaces for students in lower-income neighbourhoods. Measures include building shade structures and installing energy-efficient air conditioning systems to reduce indoor temperatures in schools by 15-20C (59-68F), and providing cooling relief for students who live in hotter neighbourhoods.

"Increasing building standards and building in a more energy-efficient way is integral to mitigate the effects of extreme weather, and the long-term effects on young children," says O'Sullivan.

But gathering data for the heat maps can prove challenging. The project relies on accurate temperature readings from various sources, including community volunteers, weather stations and satellites.

"In some cases, there can be gaps in heat data particularly in areas where there is limited monitoring infrastructure. This can lead to incomplete heat maps, potentially overlooking hotspots or temperature extremes," says Singer.

Defining the effectiveness of cooling measures can also be complex. Air conditioning, green roofs, tree planting and heat awareness campaigns have varying levels of advantages for vulnerable communities, and will depend on factors like the local climate of an area, ambient pollution – which can be 5% higher than in more rural areas - as well as building design and government maintenance and policy.

"Evaluating the impact of these measures requires rigorous monitoring and analysis which might not always be readily accessible," says O'Sullivan.

Air conditioning and improving energy efficiency can help keep people cool in hot weather but these measures may not be cost-effective and accessible for poorer families. Some experts argue that these solutions may not address the underlying issue of energy poverty in low-income communities.

"In places like New York City, there are many people who don't have [air conditioning] units because there are building regulations or economic barriers to purchasing them. They also use up a lot of energy," says Ngo.

"Challenges such as government legislation, funding and data availability and technical difficulties have limited NOAA's mission to extend the mapping project across the US and worldwide," says Zabow. "Governments and local decision makers often prioritise emergency responses to other climate risks, such as hurricanes, flooding and drought, over heat mitigation."

"If a tornado, an active wildfire, or flooding comes through a town, you're going to see the destruction. Heat is unfortunately harder for governments to prioritise and fund. We hope to partner with more federal partners and volunteers to build more cooling solutions to protect young children," she adds.

Heat is becoming increasingly dangerous and it's a threat that is not going away. Community heat maps may not solve the long-term problem, but they are a step in the right direction, by providing awareness and empowering vulnerable children and their families, like the Howards.

"How do we fight off these massive heatwaves that keep happening year upon year?" says  Christina. "We want to give our kids the tools to protect themselves from extreme heat right now and when they're older. Who knows what might become of the world in the future there's not enough heat research and actionable change."

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