Do Trees in Cities Help or Harm Our Health?

Air pollution: outdoor air quality and health (National Institute for Health and Care Excellence, Dec.1, 2016)

Also discussed here: Trees could make urban pollution even worse (quartz, Dec.6, 2016)

And here: Neighborhood greenspace and health in a large urban center (Nature, Scientific Reports, Jul. 9, 2015)

Today we review a guide about urban air pollution that looks into the role that street trees play with respect to reducing air pollution. The overall conclusion was that trees are unlikely to reduce air pollution and could add to it, especially if the trees reduce ventilation of air currents. This is true also of the more recent use of green walls. It is also acknowledged [in a Toronto study]that urban trees can improve health – as much as a $10,000 raise or feeling 7 years younger. Pine trees are singled out as a particular contributer to urban pollution through their emissions of volatile organic compounds (VOC) which combine with the NO2 in car emissions to produce low level ozone, one of a handful of pollutants harmful to health.

tree-area-toronto

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How Do Air Pollution Alerts Affect Public Health Use?

Effects of an air pollution personal alert system on health service usage in a high-risk general population: a quasi-experimental study using linked data (7 page pdf, R A Lyons, S E Rodgers, S Thomas, R Bailey, H Brunt, D Thayer, J Bidmead, B A Evans, P Harold, M Hooper, H Snooks, J Epidemiol Community Health,  May 23, 2016)

Today we review an analysis of the reaction of an “intervention”  group of patients with air pollution- related illnesses (cardio-respiratory and COPD) to alerts produced by the UK’s airAware alert system over a two year period, as measured by visits to hospital emergency departments, compared to a control group which were not similarly afflicted. Results indicate a doubling of emergency admissions and four times the number of respiratory conditions for the intervention group compared to the control group. The authors conclude that some health interventions or alerts beyond a certain distribution level are harmful in terms of health service utilisation.

air-alerts

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How Can Cities Reduce Methane Emissions?

Mitigation of methane emissions in cities: how new measurements and partnerships can contribute to emissions reduction strategies (39 page pdf, Francesca M. Hopkins, James R. Ehleringer, Susan E. Bush, Riley M. Duren, Charles E.Miller, Chun-Ta Lai, Ying-Kuang Hsu, Valerie Carranza, James T. Randerson, Earth’s Future, Sep. 10, 2016)

Today we review research into methane emissions from cities which along with other greenhouse gases contributes to climate warming. Cities themselves account for 70% of GHG emissions globally.  Unlike CO2 however, methane emissions are more easily managed at the city level whether they come from transportation and the increased shift to natural gas as a fuel for city vehicles or, secondarily, from landfills where methane is emitted from decomposing organic materials or, thirdly, from leaks in the systems delivering natural gas to users. One of the major problems is the lack of accurate inventories of methane emissions which in some cities results in an underestimate of 50%. Some efforts being made in the transportation sector to reduce CO2 emissions include shifts to the use of propane or natural gas but these may have unintended consequences in terms of their contribution as a radiatively active gas to the greenhouse effect. Landfill emissions may be reduced by simply reducing the amount of waste generated though pricing of garbage or encouraging home composting.

methane-emissions

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The Future of the World and Cities in It

Urban futures: anticipating a world of cities (6 page pdf, Geci Karuri-Sebina, Karel-Herman Haegeman and Apiwat Ratanawaraha, Foresight, Sep. 10, 2016)

Today we review an introduction to a series of papers on cities from a foresight point of view. It begins with a prediction that the city has evolved from the city-state in Ancient Greece to city-worlds in the next 100 years. By 2050, 70% of the world’s population will live in urban areas, compared to 54% today. While cities can improve economic prosperity, reducing poverty and becoming more inclusive socially, there are also downside risks of unemployment and poverty, as well as tensions based on religion, race and values – in addition to the major health threats that resulting congestion and emissions from downtown traffic where city government has not taken steps to alleviate. While cities are good at generating problems they also have a problem solving capability. The paper ends on an optimistic note: “In a world that increasingly appears ungovernable, cities – not states – are the islands of governance on which the future world order will be built”- something that those who try to come to grips with climate change and urban air pollution need to acknowledge and take count of in reducing carbon emissions and adapting to the challenge.

Indoor and Built Environment

Indoor and Built Environment (Photo credit: Wikipedia)

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Must Cities Shrink to be Sustainable, even with Increased Urbanization?

Sustainability for Shrinking Cities (9 page pdf, Dustin L. Herrmann, William D. Shuster, Audrey L. Mayer and Ahjond S. Garmestani, Sustainability, Editorial, Sep. 7, 2016)

 

Today we review an overview (and editorial) focused on sustainability for cities in the face of increasing urbanization worldwide and to the recent trend toward shrinking cities because of economic depression and the hollowing out of city centres as a result. Many large growing, economically-healthy cities tend to replace urban greenspace and urban parkland with high income residential or commercial developments with significant negative impacts on a healthy environment. Shrinking economically poor cities on the other hand are faced with vacant downtown lots some of which steer toward sustainable cities through improved water filtration, dampening of urban flash floods and carbon sequestration. For many coastal cities, sea level rise and threats to human health from more frequent hot spells as a result of climate warming are other issues on cities to adapt sustainably with more thoughtful urban planning.

shrinking-city

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Can the Paris Agreement on Climate Change Work?

The Paris Agreement and the New Logic of International Climate Politics (28 page pdf, Robert Falkner, International Affairs, Aug.31, 2016)

Today we review an analysis of the international negotiations from the top-down 1996 Kyoto Accord that today applies only to 15% of global carbon emissions, to the 2009 Copenhagen Accord that failed to reach consensus on a global emission reduction goal but managed to provide an umbrella for all participating countries for future negotiations. To the bottom-up Paris Agreement in 2015, signed by 195 nations, combines domestic politics with international commitments through a “naming and shaming” approach, voluntary national commitments,  rachet-up reviews every five years and, perhaps most importantly, definition of a long term goal to reach “net-zero” emissions or “emission neutrality” between 2050 and 2100. As these voluntary commitments would result in a global warming of 2.7 C above pre-industrial levels, further reductions beyond the pledges are needed. The author cautions that “the Paris Agreement cannot be expected to ‘fix’ the climate problem; it can only provide a supportive framework within which states and other actors can achieve the required emissions cuts.”

Carbon emissions from various global regions d...

Carbon emissions from various global regions during the period 1800–2000 AD (Photo credit: Wikipedia)

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Measuring Exposure to Urban Air Pollution Where People Work rather than Where they Live.

The Impact of Mobile-Device-Based Mobility Patterns on Quantifying Population Exposure to Air Pollution (11 page pdf, Marguerite Nyhan, Sebastian Grauwin, Rex Britter, Bruce Misstear, Aonghus McNabola, Francine Laden, Steven R. H. Barrett, and Carlo Ratti, Environmental Science and Trechnology, Aug. 12, 2016)

Also discussed here: Air pollution threat hidden as research ‘presumes people are at home’: study (The Guardian, Aug. 24, 2016)

And here: Urban air pollution is worse than we think—but better data might solve the problem (Barbara Eldredge, CURBED, Aug. 30, 2016)

Today we review research into a study in New York City that compared the exposure to urban air pollution during an active day at the place of work and travelling to that rather than as earlier exposure studies have done only at the place of residence. The results indicate, first of all, that the highest concentration of PM2.5 is not surprisingly in central Brooklyn and Queens and in the southern half of Manhattan Island. Pollution levels at places of work compared to those at residences was 10 μg/m3 higher which suggests that a higher congestion charge be applied to vehicles which enter the high emission zones (which is the basis for the [present congestion charge zone in London, UK) .Future applications of this research when self driving cars are the norm might involve automatically controlling their movement to avoid adding to the pollution levels in some packets of the city.

air-pollution-smart-city-mit-study-nyhan-3

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