Urban planning expert Diana Mitsova and neurobiologists Lilah Besser and Elaine Le argue that lack of street shade in historically low-income neighbourhoods is trapping older Americans in their homes during the summer months.
In addition to the obvious heart health benefits of light exercise, staying active can delay the onset of Alzheimer’s disease and dementia. Access to the outdoors, socializing and gentle exertion are important factors in staving off cognitive decline in older adults. Poor street design, however, appears to be sabotaging public health efforts to keep senior citizens moving and meeting.
Urban Heat Islands
In the study published in the Journal of Urban Health this September, researchers explain that neighbourhoods with the highest street temperatures have the lowest number of seniors outside and walking. Not only do high temperatures take people off the streets, they can also cause direct harm due to heat exhaustion.
While these findings might be discouraging, they do present an opportunity. City blocks or areas where the built environment contributes to extremely hot local temperatures are known as ‘urban heat islands’. You might have noticed that walking across a carpark for example can feel hotter than walking across a grassy park. The authors suggest that taking another look at how planning decisions can improve quality of life for seniors in urban heat islands could lead to better choices when cities decide renewal projects or maintenance matters.
Hot Streets
The amount of green space in the area, tree planting and heat holding building materials have direct consequences for street level temperatures. Places with fewer trees, parks, gardens and larger roads, more concrete surfaces and density are, on average, hotter.
‘While more research is required, our findings highlight the urgent need to address urban heat islands in historically marginalized communities,’ said Mitsova in a press release by Florida Atlantic University. ‘This is especially critical as older adults in these areas, who are more vulnerable to heat-related health issues, face greater exposure to extreme temperatures and associated health risks.’
Historic Highs and Historical Records
The Florida scientists used data collected from US census tract IDs provided by the Federal Highway Administration, historic red lining score tracts from the US census, the 2011 National Land Cover Dataset (NLCD) and the American Community Survey (ACS, 2017 5-year estimates) amongst others to map the hottest urban streets across the USA.
It turns out that lower income areas are hotter than their more privileged neighbours and it’s not always down to natural geography. Historically, cities have under invested in street design and urban renewal projects in deprived areas. This lack of attention leads to inhospitable environments that, in the long term, generate urban heat islands.
High Temperature, Low Investment
They found that the areas highlighted as the most economically and socially deprived also had higher land surface temperatures than their richer neighbours. Seniors with higher average incomes (over $125,000 per annum) were more likely to live in cooler communities than their less well-off cohorts.
Low income or less desirable areas were not necessarily warmer because they were built in areas that were shunned as too sunny by people with more resources. Examining the relationship between green spaces and land surface temperature showed that thoughtful community planning can make a difference to how hot it gets. Richer neighbourhoods with more green spaces and less concrete did not get as hot.
Too Hot to Move
When the researchers compared the activity levels of seniors to land surface temperatures in their neighbourhood, they found that seniors reported less time spent walking if their streets were sweltering. While both advantaged and disadvantaged communities experienced high temperatures, the more advantaged seniors were able to escape the heat in air-conditioned cars or public transit. Lower income seniors were not only trapped inside but also more likely to suffer the ill effects of high temperatures.
Similarly, better off older adults were able to cool off in green backyards while elders living in apartments had little access to the outside and less tree shade over balconies.
This study is only a snapshot and relies on self-reported data, so it can’t give us definitive answers. The findings don’t necessarily attribute the lack of walking to street temperature. On the other hand, this research could encourage public health officials to collaborate with their colleagues in urban design. It could be worth experimenting to see how bringing more green spaces to historically deprived areas helps elderly citizens to step outside in the summer.
Mitsova D, Besser LM, Le ET. Summer Heat, Historic Redlining, and Neighborhood Walking among Older Adults: 2017 National Household Travel Survey. J Urban Health. Published online August 12, 2024. doi:10.1007/s11524-024-00892-6
