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How Atlanta Can Fight the Health Effects of Urban Heat

Tanner “Tan” Brantley is an advocate of black environmentalism: intersectionality and intentionality for environmental action.

Nighttime thermal images of suburban (left) and urban (right) Atlanta.

Nighttime thermal images of suburban (left) and urban (right) Atlanta.

Urban Sprawl and Human Health in Atlanta

As is evident to anyone who has visited or lived in Atlanta, Georgia in the past ten years, Atlanta has had a steady increase in development, and population in recent years. This has been occurring at rate which is seems too much for developers and city officials to properly handle. In Atlanta, the rapid urbanization and population increase has a hazardous impact on human health by way of a diminished air quality and increase in extreme temperatures. Atlanta has had peak temperatures which have ranged from 92 to 106 °F.[1] Mayor Keisha Lance Bottoms said that, “If current trends continue, Georgia is projected to see an increase in “dangerous heat days” from an average of 20 days a year today to more than 90 by 2050.”[2]

This decreased air quality and increased temperatures are in many ways interconnected and a result of the rapid urban sprawl in Atlanta. As stated by the EPA, “[u]rban sprawl is the haphazard spreading of low-density residential, commercial, and/or industrial develop­ment into rural areas near cities.”[3] A study of the Northeast Ohio Urban Sprawl found that some detrimental effects of urban sprawl were “[i]ncreased and insufficient land use and energy consumption, [i]ncreased traffic congestion, [and] [n]egative environmental effects, such as reduced air and water quality and loss of open space and other natural gases.”[4] Atlanta is currently plagued by all of these issues.

Urban Sprawl, the Urban Heat Island Effect, and Climate Change

Atlanta is being subjected to a common phenomenon that also plagues other cities which struggle with urban sprawl, the urban heat island effect (“UHIE”). Heat islands are developed areas where the temperature is hotter than the surrounding rural areas.[5] UHIE is a phenomenon in which air pollution and heat distribution create a uniquely hot atmosphere in urban areas. Buildings, roads, infrastructure and human activity are the factors which sustain and intensify heat islands. To be specific, buildings, roads, and other infrastructure absorb and emit more heat than a rural area with plentiful green areas full of vegetation. This results in increases daytime temperatures and reduced nighttime cooling. Just think about that time you were a kid and decided to walk barefoot on a hot summer day. We all remember how deeply we regretted venturing from the grassy lawn to the scorching pavement for the first time. Basically we have surrounded ourselves by that scorching pavement on all sides, and made the grassy lawns a fifteen-minute drive away.

Even though the temperature difference between the rural and urban area may not be abundantly clear during the day, at night the difference could be as much as a staggering 22°F. These temperature increases are not limited to being felt outside either. The absorbed heat increases the temperature inside of buildings because it is slowly absorbed throughout the entire building over the day. This in turn causes people to use their air conditioners more. The increased air conditioner use increases air pollutants emitted, which creates a more robust ground ozone, or smog. “As temperatures increase, warmer air forms ground-level ozone, known as “bad ozone,” which is a powerful pollutant that contributes to a rise in asthma attacks”.[6]

It is already hard enough to breathe on a really hot day. The addition of smog to let's say 90-degree weather would make it difficult for even a person without any health conditions to be outside. Although there are various scientific studies that assert that extreme heat does not further aggravate significant respiratory conditions such as asthma, as will be addressed below, they are not persuasive. In Heat Islands, extreme heat and air pollution are presumed to act in concert to compromise the air quality and thus greatly impact the health and quality of living for local residents.

The UHIE poses a continuous and serious threat to the health of residents of Atlanta. Excessive heat, smog, and simply poor air quality, also compels residents to drive more frequently.[7] The elevated vehicle miles traveled (“VMT”) exacerbates the already existing heat island because of the vehicle-related pollutants. This increase in vehicle emissions contributes further to the degraded air quality. Millions of people “in the Atlanta area experienced 118 days of degraded air quality in 2016 [which] increase[ed] the risk of premature death, asthma attacks and other adverse health impacts.”[8]

In particular, children, the elderly, low-income communities, the homeless, people with heart disease, and lung disease (“sensitive health groups”) are subjected to a higher risk of heat strokes, mortality, respiratory difficulties, and heat-related illness as a result of this degraded air quality and high temperatures. The increased temperatures “make it easier for mosquito-borne illnesses such as Zika virus, dengue fever, malaria, and West Nile virus to survive” which in turn exposes the general population to even more health-related dangers.[9] “The Centers for Disease Control and Prevention estimates that from 1979–2003, excessive heat exposure contributed to more than 8,000 premature deaths in the United States. This figure exceeds the number of mortalities resulting from hurricanes, lightning, tornadoes, floods, and earthquakes combined.”[10] Unfortunately, as the extreme temperatures due to the UHIE increase “heat-related mortality risk in urban areas” and are likely to escalate due to climate change.” [11]

While global climate change has caused temperatures to rise in cities, regional pollution amplifies localized temperature increases. Georgia only has two cities with a population of at least 200,000, the city limits of Atlanta with roughly 450,000 residents, and Columbus which has a little over 200,000 residents.[12] In the Atlanta region there are roughly 4,628,400 people.[13] Seeing as Georgia is ranked 11th on the list of U.S. states with the highest Carbon Dioxide emissions, it is likely that this is mainly caused by the 4.6 million Greater Atlanta residents.[14] The effects of carbon dioxide emissions are likely to be centralized in cities since carbon dioxide quantities “rise with economic growth and are concentrated in cities (since these are the main centers of production, consumption and waste generation).” [15] Thus, cities like Atlanta are more significantly impacted by climate change when it is paired with UHIE.

The Urban Sprawl Feedback Loop

In Cobb County, the McDonough-Atkinson plant provides energy to the Metropolitan Atlanta area through the utilization of natural gas.[16] While the McDonough-Atkinson Plant’s nitrogen oxides (“NOx”) and sulfur dioxide (“SO2”) emissions are slightly under the national emission averages, the carbon dioxide (“CO2”) emission level is almost seven times the national average.[17] This is concerning because CO2 “is the primary greenhouse gas emitted through human activities, making up over 80% of the United States' annual greenhouse gas emissions from those activities.”[18]. Power plants, such as McDonough-Atkinson, also account for about 47% of PM2.5.[19] These are particles that form in the atmosphere as a result of complex reactions of chemicals like SO2 and NOx. They penetrate deep into the lung tissue and bloodstream.[20] As a result, these particles “may cause significant respiratory or cardiovascular problems that can shorten an individual’s lifespan [and] children, the elderly, and people with cardiovascular or lung diseases such as emphysema and asthma” are particularly put at risk by these pollutants.[21] Once again, paired with the extreme temperatures that occur because of those pollutants, sensitive health groups are put at an even higher risk.

The urban sprawl fuels a positive feedback loop that keeps sensitive health groups at risk. As the demand on McDonough-Atkinson power plants increases, more GHG and particular matter is released into the atmosphere. This further contributes to smog, which in turn exacerbates the UHIE. A bolstered UHIE triggers an increase in VMT and air conditioning usage as people stay drive more, and use their air conditioners for longer. As VMT and air conditioning use elevates, more heat is trapped by the bad ozone and smog, and the energy demand from the McDonough-Atkinson plant is heightened. Thus, the cycle is self-sustaining when left alone. Urban sprawl further exacerbates this issue because of the increased population, development, and diminished green space. All of these factors further contribute to the Urban Heat Island Effect.

Monitoring of Urban Sprawl’s Effect on Air Quality

A well-established way to monitor the effects of urban sprawl is through analysis of UHIE signals such as temperature and air quality. The EPA recommends the regional monitoring of air temperatures, surface temperatures, and seasonal and daily temperature patterns.[22] The EPA also suggests utilizing satellites, ground-based thermal sensing, or aircraft-borne instruments to monitor heat islands. Air Georgia has opted to measure more than temperature data. “Currently, Air Georgia employs continuous and non-continuous monitoring by way of “over 100 air samplers (called monitors) [which] are located throughout Georgia that measure for nearly 200 air pollutants.”[23] The data from the collectors showed in 2018 the residents of Atlanta were subjected to 148 days of “Moderate” air quality and 8 days that were “Unhealthy for Sensitive Groups.”[24] Rather than focusing on only on temperature, monitoring air pollutants can be effective as well. Because the levels of air pollutant concentration are directly related to the heat trapped by the bad ozone, it is likely that a decrease in pollutants means a diminished UHIE.

Furthermore, temperature may not account for the other ways pollutants impact human health and the environment. With an increase of population and temperatures comes a greater water demand. The current water system is not equipped for the influx of population as “[h]alf of all Georgians drink water drawn from the Chattahoochee River.”[25] Aside from the demand put on the Chattahoochee, the water quality is threatened by “rampant suburban growth and inadequate or ageing water and sewer systems; runoff from paved surfaces, agriculture lands and lawns, erosion from construction sites; and seepage from septic trucks.”[26]

Moreover, the rapid expansion of Atlanta has led to a substantial loss of green space. A majority of the loss “is a direct result of encroachment by low-density sprawl development into forested and agricultural areas.”[27] “The deforestation and loss of vegetation, coupled with increased pavement and rooftops, helps attribute to heat island effect and contributes to the region’s air pollution as well.”[28] The extreme heat can also cause roads to crack or buckle and harm native plants and wildlife as well. It deters outdoor activities and tourism as people prefer not to spend time in the heat and associated air pollution.[29]

Scientific Uncertainties About Urban Sprawl, UHIE, and Their Effect on Human Health

The most significant criticism of urban sprawl impacts on human health have been directed at the limited scope of UHIE research. These critics have tended to focus on the decreased number of cold related deaths as a result of UHIE. A U.S. impact assessment estimated that UHIE increased heat-related deaths by 1.1 per million population, but decreased cold-related deaths by 4 per million.[30] Although there has been more research into the costs of UHIE rather than the potential benefits, that should nonetheless be inconsequential.[31] The results in this particular assessment were “derived simply by relating information from death certificates on the underlying probable cause of death to urbanization level in various cities.”[32]

A different study concluded that extreme temperatures led to an increase in childhood emergency department admissions (“EDAs”).[33] This study also supported that the EDAs occurred most in times of extreme heat rather than extreme cold.[34] Another study conducted in nine U.S. cities to examine the relationship between apparent temperature and mortality strongly supported a linear relationship.[35] What is important to note is that the study which suggests that heat islands have led to less cold related deaths, ignores that the concern of heat island studies is that the global temperature is increasing. Populations, sensitive health groups in particular, are more likely to be exposed to extreme heat rather than cold and therefore that there are less cold related deaths is irrelevant.

The Mayor and MARTA

There has been a concerted effort to experiment with different programs and initiatives to combat urban sprawl by Mayor Keisha Lance Bottoms. The most significant initiative has been for MARTA expansion. Transportation, was shown in 2017 to account for roughly 34% of U.S. CO2 emissions.[36] MARTA stated in the 2019 Sustainability report the transit system “reduced regional GHG emissions by keeping 1,725,435 metric tons (MT) of CO2 out of the atmosphere in 2017.”[37] The report equated this to keeping “366,334 cars of the road for a year.”[38] This expansion, which was only set to a half penny tax, was rejected by the residents of Gwinnett county and has been stalled by those of Cobb county. Although this has been a successful initiative for cutting the Atlanta CO2 emissions, it has begun to stall.

Aside from the MARTA initiative, Atlanta has been encouraged the private sector to implement smart growth initiatives to mitigate urban sprawl implications. The EPA’s smart growth initiative encourages projects that are in accord with the ten smart growth principles. Those ten principles include encouraging (1) mixed land use, (2) taking advantage of compact building design, (3)creating a range of housing opportunities and choices, (4) creating walkable neighborhoods, (5) fostering distinctive, attractive communities with a strong sense of place, (6) preserving open space, farmland, natural beauty, and critical environmental areas, (7) strengthening and directing development towards existing communities, (8) providing a variety of transportation choices, (9) making development decisions predictable, fair, and cost effective, (10) and to encourage community and stakeholder collaboration in development decisions.[39]

Green Roofs in Atlanta

In accord with the smart growth principles, I suggest directing projects towards the impacts of heat islands to improve the air quality (the temperature and pollution concentrations), and manage the effects of urban sprawl. The EPA has five recommended strategies and technologies for heat island cooling which include increasing the number of trees and vegetation, green roofs installation, cool roofs installation, cool pavements projects, and smart growth projects.[40] I believe a highly effective strategy in Atlanta would be the implementation of a green roof permit program.

A green roof permit program would encourage developers to incorporate, among other green initiatives, green roofs in any new or old building they are developing. “A green roof is a layer of vegetation planted over a waterproofing system that is installed on top of a flat or slightly–sloped roof. Green roofs are also known as vegetative or eco–roofs.”[41] These may include grass, shrubs, or even trees.[42] Outside of providing a protective layer that shades the building from direct sunlight, green roofs utilize the natural process of evapotranspiration to cool the surrounding air. [43]

Evapotranspiration is “the movement of water from the soil both by evaporation and by transpiration, the process by which water exits through pores in the leaves of plants. It takes energy to turn the liquid water into vapor, and the process of evapotranspiration therefore cools the plant.”[44] Green roofs take advantage of the direct sunlight in a way that keeps all of that same energy from being transferred into the building. Less heat being transferred into the building reduces the need for air conditioning. Green roofs have been proven to reduce the transfer of heat from the exterior to the interior of a building as much as 72% and a decrease in temperature as much as 30 to 40 °F.[45] Cooling the interior of the building results in less air conditioning being used.

In addition to reducing pollutants by lowering the energy demand, green roofs can remove pollutants from the air. “Plants on green roofs can capture airborne pollutants, atmospheric deposition, and also filter noxious gases.”[46] In a 2018 EPA case study that examined a large-scale green roof project in Kansas City and the surrounding area, it was estimated that nine counties would experience reductions totaling 734 pounds of SO2, 384 pounds of NOx, and 269 tons of CO2 avoided in 2020.[47]

Chicago is another city that has done extensive research into green roofs and successfully provided incentives for developers to incorporate them into new projects. Chicago has the Green Permit Benefit Tier Program which allows projects with green initiative projects that qualify under the program to receive various benefits.[48] In a rapidly growing city, such as Atlanta, a program like the Green Permit Benefit Tier Program would be a low-cost way to encourage sustainable and healthy growth. In 2003, there was a green roof installed on top of the city hall building.[49] The City Council of Atlanta could use the City Hall building as an educational resource and foundation for what a qualifying project would entail.

The City of Atlanta should implement a green roof permit program as soon as possible because the danger heat exposure and pollutant concentrations poses to sensitive health groups. Green roofs would be a unique way to facilitate economic growth, while addressing major health concerns. Green roofs combat the UHIE by decreasing the amount of heat transferred into the building, reducing the amount of heat returned to the air, reducing the use of polluting air conditioning units, and reducing the energy demand in the nearby power plants. All of this occurs while the vegetation is removing air pollutants from the air. In Atlanta, a city that last year had over 100 days of degraded air quality and where the temperature has been as high as 106 °F in the past ten years, green roofs could be an invaluable asset.[50] Green roofs would be a unique way to facilitate economic growth, while addressing major health concerns.


[1]Atlanta – Highest Temperature for Each Year, Current Results (Feb. 25, 2020), https://www.currentresults.com/Yearly-Weather/USA/GA/Atlanta/extreme-annual-atlanta-high-temperature.php.

[2] Keisha Lance Bottoms, Mayor, City of Atlanta, Testimony Before U.S. Senate Special Committee on Climate Crisis (July 17, 2019), (transcript at https://www.atlantaga.gov/Home/Components/News/News/13092/672).

[3]Urban Sprawl Modeling, Air Quality Monitoring, and Risk communication; The Northeast Ohio Project, U.S. Envtl. Prot. Agency (Nov. 2002), https://nepis.epa.gov/Exe/ZyPDF.cgi/10004FWI.PDF?Dockey=10004FWI.PDF.

[4] Urban Sprawl Modeling, Air Quality Monitoring, and Risk communication; The Northeast Ohio Project, supra.

[5]Heat Island Impacts, U.S. Envtl. Prot. Agency (Feb. 25, 2020), https://www.epa.gov/heat-islands/heat-island-impacts.

[6] Bottoms, supra.

[7] Current Results, supra.

[8] Jennette Gayer, Trouble in the Air: Atlanta’s Health at Risk With 118 dirty air days in 2016, Environment Georgia (Jun. 27, 2018),https://environmentgeorgiacenter.org/news/gae/trouble-air-atlanta’s-health-risk-118-dirty-air-days-2016

[9] Bottoms, supra.

[10] Heat Island Impacts, supra.

[11] Heaviside et. Al, The Urban Heat Island: Implications for Health in a Changing Environment Built on Environmental Health, 3 (July 10, 2017).

[12]Gerogia – 10 Largest Cities, Geonames (Feb. 25, 2020), http://www.geonames.org/US/GA/largest-cities-in-georgia.html.

[13]Atlanta Region Population Estimates, Atlanta Regional Commission (Feb. 25, 2020), https://atlantaregional.org/atlanta-region/population-forecasts-estimates/atlanta-region-population-estimates/.

[14]Rankings: Total Carbon Dioxide Emissions, 2017 (million metric tons), U.S. Energy Info. Admin. (Feb. 25, 2020), https://www.eia.gov/state/rankings/?sid=GA#/series/226

[15] David Satterthwaite, The Scale of Urban Change Worldwide 1950-2000 and its Underpinnings, Int’l Inst. For Envtl. and Dev. (Feb. 27, 2020) https://www.jstor.org/stable/pdf/resrep01817.7.pdf?ab_segments=0%252Fbasic_SYC-4946%252Fcontrol&refreqid=excelsior%3Aa7f90dd9cb3a2f42c0ccb00188860a57.

[16]Plant McDonough-Atkinson, Georgia Power (Feb. 25, 2020), https://www.georgiapower.com/company/energy-industry/generating-plants/mcdonough-atkinson.html.

[17] McDonough-Atkinson Plant, ARCGIS (Feb. 25, 2020), https://storymaps.arcgis.com/stories/80c630648bf84380be5763a2792aa68e.

[18] ARCGIS, supra.

[19]2018 Air Quality Report: Air Protection Branch, Georgia Dep’t of Nat. Res. (Feb. 25, 2020), https://airgeorgia.org/docs/report18.pdf.

[20] Georgia Dep’t of Nat. Res., supra.at 40.

[21] Georgia Dep’t of Nat. Res., supra. at 40.

[22]Measuring Heat Islands, U.S. Envtl. Prot. Agency (Feb. 25, 2020), https://www.epa.gov/heat-islands/measuring-heat-islands.

[23] Georgia Dep’t of Nat. Res., supra.

[24] Georgia Dep’t of Nat. Res., supra.at 47.

[25] James Kundell, Urban Sprawl, New Georgia Encyclopedia (Feb. 25, 2020), https://www.georgiaencyclopedia.org/articles/arts-culture/urban-sprawl.

[26] Kundell, supra.

[27] Kundell, supra.

[28] Kundell, supra.

[29] Kundell, supra.

[30] Heaviside et. al, supra.

[31] Heaviside et. al, supra.

[32] Heaviside et. al, supra.

[33] Zhiwei Xu et. al, Extreme temperatures and emergency department admissions for childhood asthma in

Brisbane, Australia, Occupational and Environmental Medicine, Vol. 70 (BMJ) No. 10, 730-735 (October 2013), https://www.jstor.org/stable/pdf/23568039.pdf?ab_segments=0%252Fbasic_SYC-4946%252Fcontrol&refreqid=excelsior%3A793db39b39410c94df88ba0a61b8c3a0.

[34] Zhiwei Xu et. al, supra.

[35] Antonella Zanobetti and Joel Schwartz, Temperature and Mortality in Nine US Cities, Epidemiology, Vol. 19, No. 4, 563-570 (July 2008),https://www.jstor.org/stable/pdf/25662588.pdf?ab_segments=0%252Fbasic_SYC-4946%252Fcontrol&refreqid=excelsior%3A8f81bb2d0d0a4d2fff867f449cd97b32.

[36]Overview of Greenhouse Gases, U.S. Envtl. Prot. Agency (Feb. 25, 2020), https://www.epa.gov/ghgemissions/overview-greenhouse-gases#carbon-dioxide.

[37]2019 Sustainability Update, MARTA (Feb. 25, 2020), https://itsmarta.com/uploadedFiles/More/About_MARTA/MARTA%20Sustainability%20Report%20120519%20Digital.pdf

[38] MARTA, supra.

[39]About Smart Growth, U.S. Envtl. Prot. Agency (Feb. 25, 2020), https://www.epa.gov/smartgrowth/about-smart-growth

[40] About Smart Growth, supra.

[41]What is a Green Roof?, Green Roofs, Nat’l Park Ser. U.S. Department of the Interior (Feb. 25, 2020), https://www.nps.gov/tps/sustainability/new-technology/green-roofs/define.htm

[42] Nat’l Park Ser. U.S. Department of the Interior, supra.

[43] Nat’l Park Ser. U.S. Department of the Interior, supra.

[44]The Benefits and Challenges of Green Roofs on Public and Commercial Buildings: A Report of United States General Services Administration, Gen. Sev. Admin. (Feb. 25, 2020), https://www.gsa.gov/cdnstatic/The_Benefits_and_Challenges_of_Green_Roofs_on_Public_and_Commercial_Buildings.pdf

[45] Gen. Sev. Admin., supra.

[46] Estimating the Environmental Effects of Green Roofs: A Case Study in Kansas City, Missouri, U.S. Envtl. Prot. Agency (Feb. 25, 2020), https://www.epa.gov/sites/production/files/2018-09/documents/greenroofs_casestudy_kansascity.pdf https://airgeorgia.org/docs/report17.pdf.

[47] U.S. Envtl. Prot. Agency, supra.

[48]Green and Solar Permit Incentives, City of Chicago, (Feb. 25, 2020), https://www.chicago.gov/city/en/depts/bldgs/provdrs/permits/svcs/green-permits.html

[49]Atlanta City Hall Pilot Green Roof, Greenroofs.com (Feb. 25, 2020), https://www.greenroofs.com/projects/atlanta-city-hall-pilot-green-roof/

[50]2017 Air Quality Report: Air Protection Branch, Georgia Dep’t of Nat. Res. (Feb. 25, 2020), https://airgeorgia.org/docs/report17.pdf.

This content reflects the personal opinions of the author. It is accurate and true to the best of the author’s knowledge and should not be substituted for impartial fact or advice in legal, political, or personal matters.

© 2021 Tanner Brantley JD MELP

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