Public Health and How Can Urban Foresters Relate toIt?

Public health is “the science and art of preventing disease, prolonging life, and promoting health through the organized efforts and informed choices of society, organizations, public and private communities, and individuals.” — CEA Winslow (1920)

I would like to start with a story from a conference I went to, perhaps 17 or 18 years ago. While I would also like to credit the regional urban forester from Ohio who made the point I am about to relate, I can’t remember what the conference was, let alone the speaker. My apologies for that.

This individual began his talk, which was on the fiscal value of maintaining trees, with a discussion of the importance of knowing how to speak to your audience. He started by hypothesizing a meeting with a town budget director. In the scenario he conjured, the urban forester goes into the budget director’s office and, by the way of asking for funding for trees, makes a case that basically comes down to “trees are good”. When the budget director does not react to that, the urban forester just repeats his point more loudly, as if the budget director did not understand what he was saying and is perhaps, also, a little hard of hearing. Finally, the budget turns her budget sheet towards the urban forester and says, “Sorry, it is not that I don’t hear you. It is that we have no line item for goodness. You will have to make your case some other way.”

I am thinking of this message in the context of Trees and Public Health. While there is no doubt that trees do good for people’s health, if we are going that make that claim in a way that gains traction with both policy makers and public health officials, we are going to have to learn more about their concerns and their language. Likewise, if we want to hear what it is these other professionals are telling us, about how tree planting, tree care and urban forestry can help them achieve their goals, we need to know how to listen to what they are saying.

So where to start? Perhaps it is best with the question, what is public health? In trying to answer this question, I made use of a webinar put together by the Center for Disease Control, called Public Health 101[1]. The definition of Public Health included above is from that series.

Epidemiology is often described as the cornerstone of public health, with biostatistics and geographic analysis close nearby. This puts diseases and other health conditionsthat affect the population as a whole or some part of it, in primary focus. In the classic case, cited in the CDC slide show, in mid-1800’s London, there was a cholera outbreak. While the thinking of the time blamed the outbreak on rotting matter, John Snow (no, not that John Snow), a London physician, had other ideas. He thought that sewage contamination of drinking water might be the main factor. By mapping the deaths from cholera in London and then overlaying the drinking water sources on top of this map of mortality, he was able to identify one water pump as highly correlated with the deaths, and perhaps the likely cause. Indeed, removing the handle from the pump and so shutting the public off from that water source worked in halting that particular outbreak and in dramatically changing London’s policy regarding what is acceptable in public drinking water.

Understandings of both cause and effect and of correlation are deeply woven into the profession ofpublic health. As the CDC describes it, the approach to public health follows four steps, moving from identifying a problem to formulating a response:

  1. Surveillance (What is the Problem?)
  2. Risk Factor Identification (What is the Cause?)
  3. Intervention Analysis (What Works?)
  4. Implementation (How do You Do What Works?

This brings us to an important first point – people engaged in public health tend to be focused on problem solving, seeking specific association and causes along with insight into the mechanisms by which the problem exists and also ways it which it might be fixed. This is good news for urban foresters. While we may not be any better than the next person in terms of describing public health issues and problems, urban foresters have invested heavily in understanding what it istrees and a healthy urban forest provides. These are the whole range of ecosystem services that most of us cannot not only describe, but also quantify and show how are of value in various different situations. We clearly have something to bring to the conversation when we speak with people involved in public health. The question becomes, how do we present this in a way that is useful to them?

Elsewhere in the CDC presentation, I was struck when, in a broad overview of 2,500 years of societal efforts in public health, the authors stated that the basis of public health is in “sanitation and environmental health”. A bit later, the connection between the environment and public health was echoed in this chart:

As the chart shows, according to the CDC, “Total Ecology” is the largest component of what determines the health of a population. Perhaps learning more about what is meant by ‘ecology’ would be helpful.

To learn more about what this chart means, I visited the CDC webpage referenced[2]. The focus of this page is “social determinants of health”. They divide the Total Ecology piece of the chart into two subcategories:

  • Social environment or social characteristics: for example, discrimination, income, and gender
  • Physical environment or total ecology: for example, where a person lives and crowding conditions

This gives us two good terms to use as we discuss the public health benefits of trees – “social environment” and “physical environment”. While the wide range of social determinants and the complex way in which public health professionals might consider them may be way over the head of a typical urban forester, they already give consideration to several of them. For example, who has not, when assessing a project to fund, considered such factors as the needs of the neighborhood, including the status of such features as the existing tree cover, the access applicants may have to other funding sources, how this project might help address additional neighborhood issues, including social issues, and so on? What goes into the environment of the public at this site and how do the elements function together and, the question we often ask ourselves, how does that affect trees? And then, turning that question around, how does, or would, trees affect the public in this environment, especially as relates to health issue?

Which lead us up to the Health Impact Pyramid, a version of which is included in the CDC presentation:

The purpose of this pyramid, as I understand it, is to highlight that there are health related activities that are largely targeted towards individuals and those largely targeted towards the larger population. These include,towards the top of the pyramid, items as personal visits to the doctor and individualized plans of treatment. Towards the bottom of the pyramid are activities such as media campaigns geared towards changing people’s behavior in making health-related decisions (e.g - eat healthy campaigns).

Urban forestry-related activities can be placed at various levels on this pyramid, from approaches where doctors counsel individuals to get out and get into nature more[3], to large scale tree plantings that are intended to provide the conditions that the doctors of the future will be writing prescriptions about for their patients to use.

Wrapping Up

The point of this short essay has been to encourage the view that a greater understanding of the interests and mission of those involved in public health is a helpful step in seeing the opportunities to better align the interests of public health and urban forestry. However, as useful as that is,themay be more value in gettingothers, outside of urban forestry and outside of public health, to come around to seeing that urban forestry is a means for putting more tools in the toolbox of all who are concerned about people’s health – whether that be at a large scale or small one. Those tools are made significantly more credible and probably more useful by having the buy-in and support of those specifically charged with people’s health.

Along these lines, one idea that occurs to me involves the establishment of some type of health effects index for trees and/or tree projects. Due in large part to iTree, we are already capable of describing many of the services provided by trees – especially those that improve the biophysical environment. Just as important is an assessment of the physical environment in which these trees will be placed – for example, the degree of air pollution – and an understanding of the people who are likely to receive these benefits. With all due disclaimers, it seems to me that the public health professional would ask, when told what it is trees can do, who does this benefit and in what way? For example, a tree that has the capability of removing a hundred pounds of air pollutants is much more valuable if growing in an environment with a high level of air pollution. It is even more so if it is near people who do not have the ready ability to otherwise escape from that pollution. That is where public health professionals can help us in formulating our points in a way that shows a specific applicability and not just a general potential.

I should also note, urban foresters need to recognize the public health concerns that are often associated with trees. The include such issues as pollen, allergies, injuries due to poorly maintained trees, and so on.

Final Note:

In this discussion of urban forestry and public health, I tend to think that the planners are never far off-stage. In that regards, I find the following citation from the American Planning Association’s publication Healthy Plan Making[4] worth consideration:

“Planning in the United States originated with a public health purpose. Planning was rooted in the need to reduce congestion, improve public health, and support social reform in housing and sanitation. Rapid urbanization resulted in overcrowded and often poorly constructed housing, noxious industrial and manufacturing uses, new levels of human and animal waste, and intensified outbreaks of infectious diseases. The planning and public health professions were joined by a shared focus on urban reform and a common goal to prevent outbreaks of infectious disease. To assist in addressing the issues that resulted from rapid urbanization, the federal government created a series of policies related to zoning, housing, and transportation. These policies have had lasting impacts on the ways in which we develop the built environment.

Over time, however, the professions began to diverge. Rather than overtly addressing issues related to health and safety, government planners’ attention focused more on land use and transportation. In contrast, public health professionals took the lead on addressing health and safety concerns.”

The purpose of the report is an exploration in which planners are including public health goals into planning, including the role of trees and access to the outdoors. It is interesting to read.

Chris Donnelly
CT Urban Forestry Coordinator
January 22, 2018

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[3]For the fun of it, visit Nature-Rx –

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