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Gwynne Mhuireach

Student in Landscape Architecture, University of Oregon

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Does urban “green” harbor healthier microbes?

We evolved in natural environments, characterized mainly by soil, water, vegetation, and the innumerable microorganisms associated with each. Many researchers have observed linkages between human well-being and exposure to green space, including mental restoration, reductions in disease and mortality, better birth outcomes, and decreased crime and violence. Explanations for why these benefits are observed are often based on the idea that humans are evolutionarily predisposed to prefer environmental settings that confer survival advantages, namely landscapes that are similar to the savannas and woodlands that humans are thought to have inhabited for thousands of years. Is it possible that vegetation is a source of the microbes we have co-evolved with over the millennium and whose presence we may require for physical and psychological health?

Westernized societies are plagued with increasing rates of auto-immune disorders. A recent study in New York City has shown that kids in neighborhoods with more street trees are less likely to have asthma, after controlling for socioeconomic factors. Several other research studies have found that children exposed to higher environmental diversity (i.e. living on a farm or forested rural setting versus living in a city) were exposed to higher microbial diversity and had lower rates of asthma and allergic disposition.

If we could quantify the relationships among human health, microbial diversity and urban green space, would it change the way we design cities? Should we put a higher priority on providing adequate green space for all urban residents? Majora Carter says, “Race and class are extremely reliable indicators as to where one might find the good stuff, like parks and trees, and where one might find the bad stuff, like power plants and waste facilities.” How can planners and designers ensure that all city residents will have a positive and equitable microbial experience as they interact with the invisible urban microbiome?

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  • May 22 2013: Green roofs are a potentially great way to introduce green space into already developed cities, but what about equal access? Those who are likely to be able to afford creating a green space are also more likely to be able to afford getting out of the city to areas with more green space. Thus, my question is this how might a planner want to incorporate/tackle this issue of wanting to develop green spaces in a city with little open space to develop so all would have access and the benefits (e.g. health and aesthetically speaking)?
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      May 22 2013: What if green roofs were required by building code? They have numerous other benefits, like reducing building energy use for cooling and decreasing the urban heat island effect.
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        May 22 2013: OK so you totally need to check out last year's TED Convo where we cover this (http://www.ted.com/conversations/11577/if_green_roofs_were_mandatory.html). Also today my Biological Diversity Class is talking about rooftop beekeeping http://www.ted.com/conversations/18440/can_urban_beehives_increase_fo.html.

        Which makes me think .... I wonder how efforts like urban beehives influence the urban microbiome?
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          May 22 2013: That is a good question, even in that other discussion I don't think anyone had considered the impact of bees on the urban microbiome.

          I almost think that in this case, the impact of the urban microbiome on bees may be a larger concern than the impact of bees on the urban microbiome. Surely bees have their own endemic microbes, but cities already have a substantial insect population, so I'm not sure how much bees could contribute to the present urban microbial cloud, especially in a way that affects human health. However, with all the concerns of colony collapse threatening bees, it may be wise to examine the health and robustness of bee colonies already in cities (Paris is apparently an urban bee hotspot). Also studying whether making bees more cosmopolitan and widely spread will increase the spread of bee diseases and parasites, and if this significantly negatively impacts their well-being.
        • May 22 2013: One would expect that urban beehives would help with the pollination of flowers which would have positive benefits for the surrounding area. However this one article points out in NYC there actually was a lack of flowers for the bee population to pollinate and thus in some areas you get an over concentration of bees: http://www.wnyc.org/articles/wnyc-news/2012/jun/25/urban-bees-may-be-running-out-foraging-ground/
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          May 22 2013: I think this just supports the need for more green space in urban areas, especially if we are incorporating urban beehives. I think it is also important to construct the green spaces with native vegetation, so that the pollinators are matched with the species they have co-evolved with, this would maximize benefits to the flowers and the bees
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        May 22 2013: In Eugene, it was only recently that we were even allowed to build green roofs. THere are now specs for green roof construction and these have to have a permit and pass inspection. Portland is well ahead of us in the progression of moving toward more green building practices. They are like our older sibling and we follow their lead.
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          May 22 2013: Of course, in Eugene we have problems with maintaining greenroofs over the summer. They often need to be watered during the dry months of the summer.
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        May 22 2013: Wow Ben you flipped it. So this makes me think about the impact of the urban microbiome on the health of urban gardens and urban spaces. I wonder if there is a link? I wouldn't be surprised.
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        May 22 2013: In addition to green roofs, some countries are also incorporating green walls into their city design. In 1994, Toronto displayed an indoor green wall that was used for bio-filtration. It might be interesting to consider adding indoor green walls inside hospitals to increase healthy microbial diversity. I think the more green space included in urban areas the better, and including them in building code is a great idea
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          May 25 2013: Sandra, check out these green walls: http://gsky.com/green-walls/. This is also in response to a comment by Ben. This technology will allow for further development of green space in cities so it won't be limited to roof tops. Plus the amount of diversity that can occur with these walls has the potential to significantly expand the urban microbiome because of how many green walls can be added throughout a city.
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      May 22 2013: The first thing to understand for any city planner that wanted to improve the "green" in a city would be how far the effect of microbial "gardens" reached? Do the effects of a green area of the city reach people a mile away or 200 ft away? If money is spent in affluent areas to improve biodiversity does that reach people living in poorer areas?
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        May 22 2013: Great point. We have been thinking about the BioBE Center http://biobe.uoregon.edu/ about the spatial distance of a person's microbial "aura". You are taking this to another level and thinking about the spatial distance of a green space "aura".
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        May 25 2013: This comment highlights the importance to make sure that the distribution of new green spaces are not clustered in only affluent areas, but they are distributed across a city so everyone can benefit from them.
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      May 22 2013: Given what I've witnessed in Columbus, cities can make concerted efforts to add green space by including it in any redevelopment process. Most of the new construction/redevelopment around Columbus has included green roofs, tree-lined streets, parks, and mini gardens. All of these areas are not necessarily in affluent locations. Convincing the owner of every building to spend the money to develop a green roof may not be possible, when cities undergo redevelopment of a once non-green area, they have the ability to make it green regardless of the socioeconomic status of the people found in the area.
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        May 22 2013: What do you think are the major factors that influence change in city planning? How much is scientific data used? Do you think that microbiome data, if it is ultimately shown to have strong links to health, would play a role?
        • May 23 2013: I think both environmental sustainability and green spaces are becoming a prominent part of city planning because science has elucidated how our environment affects our physical and mental health, which in turn affects other factors such as crime rates. Local organizations such as Beyond Toxics (http://www.beyondtoxics.org/) in Eugene are working to reduce environmental/health risks due to pesticides and air pollution in low-income neighborhoods. They also have a “healthy bee” campaign that is working to create more pesticide-free garden areas in Eugene.
          I think if there is a connection between microbial diversity and human health this will strengthen the argument for green spaces, in addition to the evidence that they may improve mental health and reduce obesity.
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      May 25 2013: Sonja, here is a good article on the use and development of green roofs in Seattle. http://www.seattle.gov/dpd/greenbuilding/docs/dpdp020213.pdf

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