Given the rapid pace of urbanization, it’s crucial to review its impacts on human and environmental health. The prevailing literature provides mixed results and little clarity.
A recently published study examines the relationships between different urban layouts, human health and sustainability.
introduction
55% of the world’s population lives in cities, and three out of 4 Europeans live in urban areas. This proportion is predicted to rise to 84% by 2050. Urban life offers more services, infrastructure, jobs and social contacts.
Nonetheless, it also increases socioeconomic inequalities and sometimes results in a sedentary lifestyle that has negative health effects.
Cities face high levels of air and noise pollution, higher temperatures and limited access to natural spaces. Thermal hotspots, so-called heat islands, are forming in urban areas, that are answerable for 75% of carbon dioxide (CO2) emissions and contribute significantly to global warming.
Compact city design
Compact cities bring more people together in a smaller space, shorten travel times and distances and encourage the usage of public transport.
This results in less pollution and a smaller carbon footprint. Short distances encourage cycling and walking, facilitate social contacts and promote a way of belonging and community.
Effects of urban sprawl
In sprawling cities, greater distances separate people from their workplaces, schools and recreational areas. This encourages private transport and results in higher CO2 emissions per person.
Fragmentation, complexity, rising infrastructure costs and irregular layouts result in discontinuous and disjointed urban spaces and exacerbate socioeconomic inequalities.
The popularity of the close link between urban structure, sustainability and population health has highlighted that many European cities have poor environmental conditions, contributing to higher rates of premature deaths.
Concerning the study
The researchers examined 919 cities in 31 countries to categorise them into different urban configurations. The aim was to learn the way these are related to environmental pollution, CO2 emissions and health.
The urban configurations were determined using local climate zones (LCZs) identified in previous studies. Their use allows the comparison of cities based on their characteristics, that are assessed in keeping with a typical standard.
European cities were classified into one in all 4 sorts of urban configuration. These were:
- Compact, high-density cities (“compact”) that were small, had a high population density, and left little natural space.
- Low-density green cities (“green”) were large, had low population densities, and had ample access to natural areas and bike paths.
- Open cities with low constructing density (“open medium” or “open low”) varied in size and population density, but were either small or medium-sized. Accessibility to natural areas was low or moderate.
These were evaluated by way of motorized traffic flows, urban surface heat islands (SUHI) to evaluate UHI intensity and air pollution (measured by tropospheric NO2 and CO2 emissions per person).
What did the study reveal?
Most European cities (261 out of 909) were classified as “open, low” cities. The “open, medium” (245) and “compact” (246) city types were almost equally represented. The “green” type was the least represented, with only 167 cities. Interestingly, cities within the Mediterranean region had the very best proportion of “compact” cities.
City centers vs. suburbs
In most cities, built local climate zones (LCZs) were predominant in city centers, while natural LCZs were more common within the outskirts. The density of motorized roads was barely higher within the suburbs, but other road types were denser in city centers and progressively decreased towards the periphery.
Traffic volume, near-surface urban heat island (SUHI) intensity and tropospheric NO2 levels were highest within the centre. In contrast, CO2 emissions increased towards the outskirts.
Associations with sustainability measures
In comparison with the opposite types, higher motorized traffic flows were related to “compact” and “open medium-sized” cities in all LCZs and all concentric regions.
Nonetheless, these two types were similar by way of traffic volume and likewise had higher NO2 pollution.
The vast majority of the urban population was crowded into “compact” or “open medium-sized cities”.
“Compact” cities had the smallest carbon footprint because public facilities were easily accessible, traffic management was higher and there have been opportunities to walk or cycle via special networks.
Nonetheless, CO2 emissions per capita were also much lower in “compact” cities than in “green” cities. Urban sprawl is accompanied by increasing complexity, irregularity and fragmentation, which reduces the connectivity and continuity of spaces.
“Green” cities had higher SUHI intensity than every other type. Nonetheless, “compact” cities had lower SUHI intensity than “open medium” or “open low” cities. Of the latter, the “open low” cities had lower SUHI than the others outside city centers.
In “green” cities, mortality rates were lowest and environmental health was healthier in comparison with all other types.
Conclusions
The study suggests a conflict between sustainability and health. The compact city configuration is theoretically the optimal, healthiest and most sustainable city model. Nonetheless, compact cities have alarmingly poor environmental quality and don’t meet health standards.
High population density is related to highly polluted areas and fewer natural spaces. Motorised transport predominates, which contradicts the theoretical advantages of footpaths, cycle paths and proximity to amenities.
Small, low-density cities are probably higher as they’re. Compact cities, alternatively, may very well be made healthier by improving long-distance transport and creating more low-traffic and green public spaces, including rooftop gardens, street trees and small gardens wherever possible, including on the grounds of homes, factories, schools, colleges and institutions. Nonetheless, this will likely increase real estate costs and exacerbate inequalities.
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