Using GIS to Form Resilient Public Health Plans

Post By: Willow Hill, Upstream Research Director of Marketing

The earth's climate is changing, and this will have a tremendous impact on human health. But the relationship between climate change and health is complex.

Ongoing climate change observations and associated prediction models show clear evidence that significant portions of the American population are experiencing various health-related repercussions. Yet the relationship between climate change and human health has not been widely recognized as a major public policy issue, which means that very little practical attention has been paid to the massive public health costs associated with existing and future climate change.

Gaining a better understanding of the interconnections between climate change and human health requires substantial investment in scientific monitoring, risk mitigation, and devising resiliency strategies. One sophisticated technology that can be employed to carry out these daunting tasks is GIS. With its remarkable capacity to distill complicated issues into straightforward, visual representations, GIS will be crucial to guiding interdisciplinary approaches to prepare for the public health impacts of climate change and formulate resilient public health plans.

How Climate Change Affects Health

General scientific consensus clusters most of the effects from climate change into four major categories:

  1. Increasing intensity, duration, and frequency of extreme weather events
  2. Rising temperatures both with and without elevated precipitation
  3. Increasing levels of carbon dioxide
  4. Rising sea levels accompanied by an escalation in coastal flooding and erosion

For each of these major climate change categories, a number of specific health effects are already being observed across large tracts of the United States. More disturbingly, many of these climate-health impacts are occurring faster than forecast over the last 20 years and clearly fall outside ranges of historical variability.

Regarding rising temperatures, many American cities and states are experiencing escalating air pollution, which is resulting in increased rates of asthma and cardiovascular disease. When temperatures rise and precipitation doesn't, this leads to intensified desiccation, prolonged extreme drought conditions, and higher levels of particulate matter that is equal to or less than 10 and 2.5 micrometers in diameter (called PM10 and PM2.5, respectively), meaning it can get into the lungs. All these conditions are leading contributors to respiratory illnesses, including emphysema and, potentially, lung cancer.

The Navigator Transformation app, developed by Upstream Research, Inc., shows current (left) and future (right) rates of adult asthma for every county in the United States. Various climate change-related phenomena, such as increases in PM2.5 and PM10, will contribute to future spikes in asthma.

Meteorologically, rare weather events—often called 500- and 1,000-year storms—are surpassing their event cycles on an annual basis. These changes in extreme weather patterns, combined with increasing annual temperatures and rising sea levels, are causing shifts in vector ecology as well, which affects how diseases are transmitted to human populations. With more instances accruing of malaria, dengue fever, encephalitis, hantavirus, Rift Valley fever, Lyme disease, chikungunya virus, West Nile virus, and now Zika, we have not yet figured out how to manage these diffusing diseases.

Rising sea levels plus an increase in significant flooding events are already impairing surface and subsurface water quality. Waterborne illnesses—including cholera, cryptosporidiosis, campylobacter, leptospirosis, and various ailments caused by toxic algae blooms—are on the rise in many regions of the United States.

Changes in water quality also exacerbate the availability of fresh water in places with depleted or difficult-to-access reserves, such as Los Angeles, Houston, Salt Lake City, and Miami. California's Central Valley is currently suffering from its worst drought in more than 1,000 years. Given that this area yields about two-thirds of the United States' fruits and vegetables, the lack of fresh water in the region is having complex effects on food supplies.

Globally, these problems have reached epidemic levels and are only increasing among urban populations. Breakdowns in essential services, such as education and trash collection, go hand-in-hand with environmental degradation and can lead to civil conflict, population migration, and significant mental health challenges.

Although Americans tend to observe these occurrences from afar, there is evidence that these impacts are affecting the United States as well. Populations of extremely low socioeconomic status are already at risk for serious health problems, and climate change is increasing the likelihood that they will get sick.

A public health crisis of epic proportions is looming, and we are largely unprepared.


In the Los Angeles basin over the next decade, temperature increases and decreases in rain will exacerbate certain respiratory and cardiovascular diseases and add a huge burden to the US health care system.

Using GIS for Public Health Resiliency Planning

The challenge now is to develop innovative, cost-effective tools that allow public and clinical health officials to combine complex climate change modeling with epidemiologic, econometric, and demographic analyses in a way that supports sound policies and sensible decision-making.

GIS is currently being used to combine meteorological, climatological, demographic, and ecological information into various models used for risk assessment, forecasting, and resiliency planning. Instead of wading through exhaustive reports and studies, stakeholders can see—on a map—how increasing temperatures and decreasing precipitation, for example, exacerbate wildland fires and give way to increasing risk from illnesses such as coronary artery disease.

GIS makes spatial correlations clear so that health care organizations can perceive the direct negative impacts of climate change on local and regional areas. With the Zika virus, for example, real-time GIS is being used to model changes in vector ecology for this emerging infectious disease. Maps show how, as temperature, precipitation, and human ecology adjust to a changing climate differently at specific latitudes and longitudes, mosquitoes extend their habitats, making mosquito-borne viruses like Zika more prevalent throughout the world.

Using GIS can also clearly demonstrate the public health costs associated with climate change. A map of Los Angeles that combines demographic, epidemiologic, and econometric data can gauge the prevalence of various diseases in the area—including chronic lung disease, which is estimated to cost $349 million to treat annually in and around Los Angeles. Climate change models of the Los Angeles basin over the next 10 years show that temperatures will likely increase while precipitation decreases, causing elevated levels of PM2.5 in the area. This will exacerbate certain respiratory and cardiovascular diseases, including chronic lung disease. While it is difficult to isolate climate change's precise impact on respiratory diseases (though scientists are trying), it is estimated that the number of asthma cases in the Los Angeles basin will increase by approximately 164,000 between 2016 and 2025, which will place a significant additional burden on health care systems.

Geographers at the Helm of Progress

At a time when federal, state, and private funding for health care in the United States is decreasing, such detailed information on climate-related health changes is sorely needed. And it is geographers who have the ability to quantitatively and qualitatively measure these effects over time.

With GIS, it is possible to understand the impacts of climate on human health, forecast specific ramifications, and develop algorithms that leverage the earth's finite resources to come up with feasible resiliency plans.

In the next 10 years, the impacts of climate change on human health will become increasingly pronounced and acute. Preparing proactively now—using GIS as a guide—will result in substantial cost savings, drastic reductions in disease, and decreased human suffering.

It is crucial that geographers get started now.

About the Author

Alex Philp, PhD, is the founder and chief science officer of Upstream Research, Inc., an emerging Esri partner that focuses on using advanced analytics to prevent disease in human populations.


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Environmental air pollution emerges as a leading risk factor for strokes worldwide

Post By: Willow Hill, Upstream Research Director of Marketing 

Originally published by The Lancet Neurology on June 9, 2016

Three-quarters of strokes worldwide could be prevented by addressing behavioral risk factors such as smoking, poor diet, and low physical activity

Environmental air pollution has emerged as one of the leading risk factors for stroke worldwide, associated with a third of the global burden of stroke in 2013, according to anew study published in The Lancet Neurology.

The findings, from an analysis of global trends of risk factors for stroke between 1990 and 2013, also show that over 90% of the global burden of stroke is linked to modifiable risk factors, most of which (74%) are behavioral risk factors such as smoking, poor diet, and low physical activity. The authors estimate that control of these risk factors could prevent about three-quarters of all strokes.

The study is the first to analyze the global risk factors for stroke in such detail, especially in relation to stroke burden on global, regional, and national levels. The researchers used data from the Global Burden of Disease study to estimate the disease burden of stroke associated with 17 risk factors in 188 countries. They estimated the population attributable fraction (PAF) – i.e., the attributable risk of stroke-related disability-adjusted life years (DALYs) – associated with environmental, occupational, behavioral, physiological, and metabolic risk factors.

Every year, approximately 15 million people worldwide suffer a stroke – of these, nearly 6 million die and 5 million are left with permanent disability [1]. Stroke is the second leading cause of disability, after ischemic heart disease [2]. Disability may include loss of vision and/or speech, paralysis, and confusion.

Globally, the 10 leading risk factors for stroke were high blood pressure, diet low in fruit, high body mass index (BMI), diet high in sodium, smoking, diet low in vegetables, environmental air pollution, household pollution from solid fuels, diet low in whole grains, and high blood sugar (figure 2). One-third (29.2%) of global disability associated with stroke is linked to environmental air pollution – and this is especially high in developing countries (33.7% vs 10.2% in developed countries).

“A striking finding of our study is the unexpectedly high proportion of stroke burden attributable to environmental air pollution, especially in developing countries. Smoking, poor diet, and low physical activity are some of the major risk factors for stroke worldwide, and controlling these behavioral risk factors could prevent about three-quarters of strokes worldwide” says lead author Professor Valery L Feigin, of Auckland University of Technology, New Zealand. [3]

“Our findings are important for helping national governments and international agencies to develop and prioritize public health programs and policies. Governments have the power and responsibility to influence these risk factors through legislation and taxation of tobacco, alcohol, salt, sugar, or saturated fat content, while health service providers have the responsibility to check and treat risk factors such as high blood pressure,” he says. [3]

“Taxation has been proven to be the most effective strategy in reducing exposure to smoking and excessive intake of salt, sugar, and alcohol. If these risks take a toll on our health, and taxation is the best way to reduce exposure to these risks, it logically follows that governments should introduce such taxation and reinvest the resulting revenue back into the health of the population by funding much needed preventative programs and research in primary prevention and health. All it takes is recognition of the urgent need to improve primary prevention, and the good will of the governments to act,” says Professor Feigin. [3]

The relative importance of risk factors varied depending on age group, country and region:

  • Household air pollution was a more important risk factor for stroke in Central, Eastern, and Western sub-Saharan Africa and South Asia (ranked third), compared to North America, Central, Eastern and Western Europe (where it was not in the top 10 risk factors) (paper, figure 2).
  • Low physical activity was a much greater risk factor for stroke among adults over 70 than among adults aged 15-69 (Appx, table 2).
  • Globally, the risk factor that was most reduced between 1990 and 2013 was secondhand smoke (31% reduction in stroke-related DALYs). The greatest reduction was in developed countries (Appx, table 4), but the contribution of secondhand smoke to global stroke burden still remains noticeable at 3.1% for 15-49 year olds, especially in developing countries where it reaches 3.2% (Appx, table 2). 
  • The risk factor that was most increased was a diet high in sugar-sweetened beverages (63.1% increase in stroke-related DALYs). The greatest increase was in developed countries (Appx, table 4), but the contribution to stroke burden remains low at 1.6% for 15-49 year olds (Appx, table 2).  
  • Air pollution, environmental risks, tobacco smoke, high blood pressure, and dietary risks were more important risk factors for stroke in developing countries compared to developed countries.
  • Low physical activity was a more important risk factor for stroke in developed countries compared to developing countries.

The authors say that because of a lack of data, they could not include some important risk factors for stroke such as atrial fibrillation, substance abuse, or other health conditions. They were also unable to account for patterns of some risk factors such as levels of smoking, BMI level, or underlying genetic risk factors. The data do not differentiate between ischemic and hemorrhagic strokes, but the authors say that while the risk factors for different types of stroke may vary slightly at the individual level, global, regional, and national policies tend to look at the overall risk of stroke.  

The study also provides information on the contribution of all 17 risk factors for stroke for 188 countries; for example, the top five risk factors for stroke in the following countries were:

  • UK & USA: high blood pressure, high BMI, diet low in fruit, diet low in vegetables, smoking (Appx, table 7 and 8).
  • India: high blood pressure, diet low in fruit, household air pollution, diet low in vegetables, diet high in sodium (Appx, table 7 and 8).
  • China: high blood pressure, diet low in fruit, diet high in sodium, smoking, environmental air pollution (Appx, table 7 and 8).

Download the study here:


[2] Christopher Murray et al. Global, regional, and national disability-adjusted life years (DALYs) for 306 diseases and injuries and healthy life expectancy (HALE) for 188 countries, 1990–2013: quantifying the epidemiological transition.  The Lancet 2015; 386 (10009), pp. 2145-2191


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