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Climate Resolve Talk with a Scientist: Helene Margolis

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Dr. Helene Margolis

How can we help communities face the impacts of climate change? As a chronic disease and environmental epidemiologist, Dr. Helene Margolis (UC Davis) works on investigating the influence of environmental factors on the health of individuals and populations and to translate that science into policy. She talked to Maya Bon for Climate Resolve about the health impacts of climate change and how we can act locally with policies to protect the public. 

What is the relationship between climate change and human health?

Dr. Helene Margolis: Within developed and developing nations, climate change -- including longer-term shifts and greater variability in global and regional climates -- is going to have a very broad range of health impacts, with different populations more vulnerable than others to those impacts. Climate change will lead to amplification of many existent global public health challenges, as well as lead to emergence of new challenges.

In addition to higher longer-term average temperatures, some of the observed and predicted changes include, greater frequency of hotter days and less cooling at night, warmer winter time temperatures with fewer days and nights of very cold temperatures. There will be altered precipitation patterns, with more extreme rain events but likely without an increase in total annual precipitation. Less precipitation will be in the form of snow, and mountain snowpack will be diminished. Snowpack, along with mountain glaciers, serves as a natural freshwater management and storage system essential for ecosystem and human health. The intensity and frequency of hurricanes and tropical cyclones, and occurrence of extreme high sea levels will increase. Greenhouse gases (GHG) also contribute to air pollution, such as ground level ozone. Those climatic changes can translate to direct health effects, such as illness or injury during extreme weather events like heat waves, severe storms, floods, and droughts, as well as from wildfires, or air pollution. Altered precipitation patterns and higher temperatures can lead to potable water deficits and in turn to both water and food insecurity for large portions of the population. Other health effects will result from ecological shifts, such as those that alter or promote survival, or change the range of pathogens in the environment, as well as that of populations of animal hosts and vectors that can transmit those pathogens to humans. Thus, increased occurrence of water-borne and vector-borne diseases are predicted both in developing and developed nations.  

Improvements in public health infrastructure will be critical for minimizing the communicable disease health risks in developing nations, it will also be important for clinicians in developed nations to be informed and vigilant for emergent communicable diseases in the populations they serve.  In addition to communicable diseases, climate change will contribute to the onset and exacerbation of chronic diseases, such as respiratory and cardiovascular disease.  A robust body of evidence indicates short term exposure to ambient air pollution, such as ozone and particulates, contribute to exacerbation of asthma (asthma attacks) and to cardiovascular events such as myocardial infarction (heart attacks).  Wildfire emissions include high levels of particulates that can impact populations near and far from the actual fire, and those emissions can contribute to ozone formation.

What groups are more vulnerable to climate change-related health impacts? 

HM: There are definitely subgroups of the population who are going to be more vulnerable to those adverse health impacts -- both because they are biologically more susceptible and because of the social determinants of health, such as socioeconomic status, access to health care, air conditioning in the home, and neighborhood assets. Social determinants can influence both biological susceptibility and exposure. There is a broad range of vulnerability with respect to climate change. In general, the populations most vulnerable to environmental stressors, including those associated with climate change, such as heat or air pollution, are infants, children and older adults, and at any age individuals with a chronic disease, such as respiratory, cardiovascular, or metabolic (for example, obesity or diabetes).  

The other problem is that children tend not to drink as much fluids and water voluntarily because their perception of thirst is different. Similarly, for older adults, including healthy older adults, they may have preexisting conditions. Even just being older, they are less able to thermoregulate, which means our various physical abilities to bring our body temperature down to a healthy range. Even if they are healthy, they are different than slightly younger adults in their ability to cast off and manage heat. You also run into those individuals, especially older adults, who have various chronic diseases, like cardiovascular, respiratory, who may be taking medications that decrease their ability to thermoregulate. Both in terms of behavior and in terms of physiology, children are especially vulnerable. Older adults, in part because of a greater physical susceptibility and because of the various complications of having a higher rate of comorphic conditions, such as cardiovascular and respiratory. 

The other health issue that affects all age groups, which is a huge, growing issue, is the obesity epidemic across the nation and across the world. The various physical health conditions associated with [being overweight or obese] actually increase a person’s biologically susceptibility for heat stress.

What are some of the specific ways that heat levels impact human health?

HM:  Any individual, regardless of age, sex, or health status, can develop heat stress if engaged in intense physical activity and/or exposed to environmental heat (dry or humid), especially if they are not acclimatized or adequately hydrated. If heat stress exceeds their physiologic capacity to cool and their body temperature rises, then a range of heat-related symptoms and conditions can develop. The medical conditions that result from heat stress and fall within the formal classification of Heat-Related Illness (HRI) represent a spectrum that starts with relatively mild and easily treated illness (heat cramps, heat edema, and heat syncope) and progresses in severity to heat exhaustion and then to heat stroke, an extreme medical emergency. While the mild conditions may not be life threatening, to prevent progression to more serious HRI, they should be treated appropriately and taken as warning signs to immediately remove an affected individual from the exposure situation.

There are also individuals who have preexisting diseases, such as cardiovascular or respiratory diseases, that can increase their susceptibility for heat stress and increase their risk of adverse outcomes related to those diseases, such as a heart attack.

Infants and young children are more vulnerable to heat stress and heat-related morbidity because they can’t remove themselves from heat exposure and they are physiologically somewhat less able to cope with heat. They lose less heat from their body, which leads to heat gain and heat illness; because they are little and don’t really know that it is dangerous, they will keep playing, which will lead them to become exposed. Once one becomes heat stressed and starts getting sick, it can keep getting worse -- as long as one is being exposed. The other problem is that children tend not to drink as much fluids and water voluntarily because their perception of thirst is different. Similarly, for older adults, including healthy older adults, they may have preexisting conditions. Even just being older, they are less able to thermoregulate, which means our various physical abilities to bring our body temperature down to a healthy range. Even if they are healthy, they are different than slightly younger adults in their ability to cast off and manage heat. You also run into those individuals, especially older adults, who have various chronic diseases, like cardiovascular, respiratory, who may be taking medications that decrease their ability to thermoregulate. Both in terms of behavior and in terms of physiology, children are especially vulnerable. Older adults, in part because of a greater physical susceptibility and because of the various complications of having a higher rate of comorbid conditions, such as cardiovascular and respiratory.

The other health issue that affects all age groups, which is a huge, growing issue, is the obesity epidemic across the nation and across the world. The various physical health conditions associated with [being overweight or obese] actually increases a person’s biologically susceptibility for heat stress. If an individual is exposed to heat, normally as a healthy individual, there are all sorts of wonderful, natural, physiologic abilities to regulate how much heat our body can handle. The most effective way to manage the heat is perspiration or sweating. In order to perspire, which is the main mode of getting back to a healthy temperature, extra cardiac output and extra respiratory function are required. If individuals have either respiratory or cardiovascular impairments, they become over taxed. That extreme heat, in addition to actual heat related illness which causes a whole fleet of emergencies where the body temperature can rise and cause organ damage or organ failure and very serious outcomes including a high rate of mortality, even in the absence of overt heat stroke, if someone has cardiovascular disease, it increases the risk of heart attack and other cardiovascular outcomes that require emergency care and can potentially lead to death. Respiratory problems, such as chronic obstructive pulmonary disease, also impair the ability to thermoregulate. Or, when taxed, individuals can have acute exacerbation of those conditions as well. Respiratory problems can exist even in young children, especially those who have asthma, which is a common and serious epidemic among children.

Has this been an issue for humans at other times in the history of our species?

HM: The rate of chronic diseases, such as cardiovascular and respiratory, have increased in part because people are living to older ages and these are often diseases of older age. Prior to antibiotics and vaccines, a common cause of death would be infectious diseases or communicable diseases and so people would die more frequently of water-borne diseases and influenza and infections such as typhus. Now that we have people living older and we have learned to better manage many communicable diseases, chronic diseases are becoming more common. To that extent, because of these increased populations with increased vulnerabilities, specifically the chronic disease, you have a greater population at risk of heat stress. Countering that, there are also technological advances, such as air conditioning, which have been positive forces. But, of course, if you don’t have access to air conditioning, it is not the solution. Again, this speaks to the vulnerable populations including the individuals who are socially vulnerable. 

What can science, government, local groups, and individuals do to help prevent heat-related illness? 

HM: The first thing we need to do is to mitigate climate change through the reduction of greenhouse gas emissions. There is a lot of work going on now at various levels to address this. Greenhouse gas emissions -- with the United States being among the highest emitters -- are mainly from vehicles, power plants, and other combustion sources. Step one is to reduce greenhouse gas emissions so that the rise in temperature is curtailed by the middle of this century. So, by 2050, the rise in temperature could at least start tailing off. Unfortunately, greenhouse gases are long lived. They anticipate that even if every country and every individual within that country could reduce emissions to pre-1990 levels, there will still be an increase in temperature. So, at the individual level and throughout the various societal levels that you mentioned, that is step one. The other part to reduce the heat of the environments in which we live would be create less impervious, or paved, surfaces, more green and shade within our built environment. The design of our community can go a long way to reducing heat exposure for individuals and communities. 

What are some steps that communities and individuals can take to be prepared for the impacts of extreme heat? 

HM: Most communities in United States and most developed nations now have an extreme heat response plan or program. Heat response plans generally include a meteorologic alert system that identifies either when a heat wave is going to occur — which in the U.S. is the National Weather Service — and plans for energy management so that people have access to air conditioning. That is a huge enterprise right there. 

There are community- and county-level actions that go into place: cooling centers and resources for individuals who may not have access to air conditioning. The state’s plan is theoretically connected to the county plan, and the counties help the various communities, but there can be great variation in the capacity of the community to actually implement a plan. The level of detail in community plans can be fairly minimal. The key is designation of responsibility and putting the emergency response personnel on alert so they are prepared to take action quickly. 

The Warm Season Alert, which I wrote about in my book, is something that is not in place. A few locations — mostly in Europe — have identified warmer temperatures as sort of "systems go." Heat emergency plans are developed for extreme heat events; a good example of a heat emergency plan is the one that California has posted on the "Beat the Heat" website.

Policy and guidelines are often fractured, so a community may have certain guidelines and regulations and the state may have some, but they are not necessarily well-coordinated. Among the most critical actions that really need to be implemented are for the protection of children and older adults, homeless individuals, or mentally capacitated individuals who may be community dwelling but cannot take care of themselves adequately. California has implemented some very rigorous worker health standards protecting individuals. Unfortunately, that came after some very sad deaths among farm workers. The biggest thing is to avoid the heat through behavioral change — to recognize the hazard that is posed by heat [and how] heat and air pollution often elevate at the same time in the mid- to late-afternoon. So, avoiding those periods of time are critical.

The other thing that is only just beginning to be recognized is the need for clinicians, whether they are nurses or physicians, to be aware of either health conditions and/or medications for those conditions or even short-term used medications, may alter susceptibility to heat. Those individuals need to be especially careful to avoid exposures. 

A genie grants you two wishes that will help fight climate change. What do you ask for? (The third wish is for anything you want -- sky’s the limit! What do you ask for?)  

HM: Number one: a universal recognition that this is occurring now and it is going to be amplified and everyone is responsible and everyone is vulnerable. So, universal awareness of the seriousness of the problems that we are facing. 

Wish number two is to not just fight climate change but to be prepared for climate change because the climate is changing. It will keep changing even if we are really effective in reducing the forces that are causing it. With that, an organized response and preparedness to respond to these, not just emergencies, but the emerging diseases that are associated with it. Along with that, an increase in community sensitivity and responsibility among individuals. People talk about human kindness and I think we see it when there are emergencies, but the wish is that that is universal, that we are all prepared to reach out and help the vulnerable people in our society who are going to be most impacted by this. 

If the sky is the limit, my wish is that — as we all face this truly global challenge — it brings us together and does not drive us apart. Within our small communities and within our global community, I hope that this inevitable force that is happening, through a global effort, will bring us together.