Climate Resolve Q&A: Helene Margolis

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 environmental impacts on individuals and populations in order 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 is going to have a very broad range of health impacts. 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 . There is a broad range of vulnerability with respect to climate change.

Because climate change is affecting some key environmental parameters such as ambient heat, winter time will not be as cold, snow may be in more in the form of ice, there will be both extreme events and longer term environmental shifts that change the physical environment in which we live, but also the physical environment in which various pathogens live, in which animals may live. So, the range of certain vectors for vector-borne diseases may change so that places that have never seen a certain disease may now see it and the clinicians may not be prepared to identify it as these changes occur.

The most imminent threats that people speak about are ambient heat and lack of water and changes in precipitation patterns. What they are anticipating is more frequent extreme events with respect to precipitation. For example, while annual rainfall may not change in the Central Valley of California, it may come down all at once as an extreme precipitation event and then nothing after that. So, there are changes that put people at risk and also change the natural environment.

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The other main concern is the changes due to ambient heat and due to the higher ultraviolet radiation that is anticipated - that there is going to be greater ozone formation, which is the common constituent in smog that exists almost any place that there is an urban environment. Heat, air pollution, and changes in precipitation have both direct and indirect effects. I would characterize the health impacts as both direct, such as those from extreme events, and indirect, such as those from the more subtle changes that we are seeing in the natural environment.

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

HM: First of all, anyone - regardless of age, regardless of health -- can experience heat-related illness. There is a spectrum of heat-related illness that actually needs clinical definitions. There are also individuals who have preexisting diseases due to heat stress, such as cardiovascular or respiratory [disease], that may be more susceptible to suffering heat stress and actual adverse outcomes associated with heat stress. Infants and young children that can't remove themselves from heat exposure can suffer more because they are physiologically somewhat less able to remove themselves. They lose less heat in their body, which leads to a 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 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: 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

LINK:	https://www.kcet.org/climate-change-la/climate-resolve-talk-with-a-sci...
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