Friday, February 28, 2014

How Does Traffic-Related Air Pollution Affect the Health of Overweight Children?

English: A schematic of the global air polluti...
Polycyclic aromatic hydrocarbon exposure, obesity and childhood asthma in an urban cohort (Abstract, Kyung Hwa Jung, Matthew Perzanowski, Andrew Rundle, Kathleen Moors, Beizhan Yan, Steven N. Chillrud, Robin Whyatt, David Camann, Frederica P. Perera, Rachel L. Miller, Science Direct, Jan. 2014) 

Also discussed here: Obese Children More Susceptible to Asthma from Air Pollution(Science Daily, Jan. 22, 2014) 

And here: Effects of fine particulate matter and its constituents on low birth weight among full-term infants in California(Rupa Basu, Maria Harris, Lillian Sie, Brian Malig, Rachel Broadwin, Rochelle Green, Environmental Research, Jan. 2014) 

Today we review research into the links between traffic exhaust and the health of children. Results indicate that three times as many obese children have asthma as non-obese children. Further that this type of pollution also has a negative effect on birth weights. Explanations have to do with the greater time spent indoors by overweight children, exposing them to more polycyclic aromatic hydrocarbons (PAH) and the fact that overweight children breath at a greater rate than non obese ones and thus have greater exposure to pollution.

 Key Quotes: 

"Our results suggest that obesity may magnify the effects of these air pollutants, putting children at greater risk for having asthma," 

"One possible explanation is that sedentary lifestyle in obese children could result in more time spent indoors, thereby increasing exposure to indoor PAH. Another may have to do with more rapid breathing in those who are obese.” 

"These findings suggest that we may be able to bring down childhood asthma rates by curbing indoor, as well as outdoor, air pollution and by implementing age-appropriate diet and exercise programs," 

Obese children exposed to high levels of air pollutants were nearly three times as likely to have asthma, compared with non-obese children and lower levels of pollution exposure” 

“Reducing methylphenanthrene exposure might be beneficial for obese children with asthma” 

“Obese young children may be more likely to develop asthma in association with greater exposure to PAHs, and methylphenanthrenes in particular, than non-obese children.” 

Fine particles and several of its constituents associated with birth weight reductions….Largest reductions for traffic-related particles, sulfur constituents, and metals”
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Tuesday, February 25, 2014

Can “Sustainability” Apply to Cities?

The Unsustainable City(10 page pdf, Matthias Berger, Sustainability, Jan. 13, 2014)

Today we review an interesting thoughtful article that examines the concept of sustainability as applied to cities which, on the surface, seem unsustainable. The author goes further though in identifying the origin of the word – not in Brundtland’s 1987 report “Our Common Future” and the introduction of the “sustainable development” concept but earlier. He concludes by suggesting that although the application of sustainability lacks time constraints that the objective is to improve the state of the city in all six aspects of the term: aesthetical, environmental, financial, functional, political, and social sustainability. urban sustainability

Key Quotes:  

This article is a discussion on theoretical and practical boundaries of using the expression ―sustainability- with respect to the scientific community, therefore avoiding sustainability becoming a euphemism for ―doing good… is not meant to be an apocalyptic or resigned view but rather a reframing of the question how we can make cities better ”  

by definition, cities are the counterparts to the hinterland, and thus they axiomatically should be and are unsustainable.”

“Cars and their infrastructure are doomed as unsustainable.. and consequently cities, which are hosts for many cars and streets, entitled unsustainable cities.”

“society as a whole is neither pure unsustainable nor should be fully sustainable, but in reality something in between.”

“Enabling sustainable cities requires an extension of the term sustainability to the six aspects of aesthetical, environmental, financial, functional, political, and social sustainability”

“sustainability means responsible management of a renewable asset, so it may last into in(de)finite time, serving future generations “

“―Today’s cities are not sustainable, yet we need not abandon urban centers and return to rural living. In short, we must have cities” “sustainability cannot address the problems associated with growth; it can only indicate how we manage the consumption of renewable goods.”
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Monday, February 24, 2014

How do Urban Sprawl and Densification Affect the Carbon Footprint?

Spatial Distribution of U.S. Household Carbon Footprints Reveals Suburbanization Undermines Greenhouse Gas Benefits of Urban Population Density(Abstract, Christopher Jones and Daniel M. Kammen, Environ. Sci. Technol., Dec. 13, 2013)

Also discussed here: Suburban Sprawl Cancels Carbon Footprint Savings of Dense Urban Cores(Science Daily, Jan. 6, 2014)

And here: Carbon Footprint Maps(University of California, Berkeley, Sep. 21, 2012)

Today we review a report that examined the carbon footprint of most cities in the USA. The authors found that the emissions from suburbs were twice those of urban cores which combine high population density with low carbon emissions. While much attention is paid by many urban planners to densification of urban cores in an attempt to reduce emissions and infrastructure pressures, it seems that the overall emissions will not change unless attention is paid to the suburbs as well, particularly in more use of electric vehicles and photo-voltaic solar cells.

. NYC carbon footprint  

Key Quotes:

“Dominated by emissions from cars, trucks and other forms of transportation, suburbs account for about 50 percent of all household emissions”

“The average carbon footprint of households living in the center of large, population-dense urban cities is about 50 percent below average, while households in distant suburbs are up to twice the average”

"Metropolitan areas look like carbon footprint hurricanes, with dark green, low-carbon urban cores surrounded by red, high-carbon suburbs,"

“the primary drivers of carbon footprints are household income, vehicle ownership and home size, all of which are considerably higher in suburbs”

“Efforts to increase population density, for example, appear not to be a very effective strategy locally for reducing emissions. A 10-fold increase in population density in central cities yields only a 25% reduction in greenhouse gas emissions.”

 "Suburbs are excellent candidates for a combination of solar photovoltaic systems, electric vehicles and energy-efficient technologies,"
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Friday, February 21, 2014

Which Emits the Most Greenhouse Gases- Car Trips or Plane Trips?

The climate impact of travel behavior: A German case study with illustrative mitigation options( Aamaas B, Borken-Kleefeld J, Peters GP, Environmental Science & Policy, Nov. 2013)

Also discussed here: Policy Analysis - Mode, Load, and Specific Climate Impact from Passenger Trips(Abstract, Jens Borken-Kleefeld, Jan Fuglestvedt, and Terje Berntsen, Environmental Science & Technology, Jun. 13, 2013)

And here: Going by car, plane, coach or train?– Climate impact from passenger travel re-calculated(11 page pdf, Jens Borken-Kleefeld, International Institute for Applied Systems Analysis, 2011)

And here: Cars and planes dominate the climate impact from travel(CICERO, Center for International Climate and Environmental Research-Oslo, May 8, 2013)

And here: Study finds climate impact of long distance trip can vary by factor of 10 depending upon mode, efficiency and occupancy(Green Care Congress, Jun. 27, 2013)

Today we review several articles that examined the greenhouse gas contributions made to atmospheric by various modes of travel. As to which is worst- car or plane trips, the short answer is: it depends. It depends on how many passengers travel together in a car and how energy efficient the car is and in terms of annual emissions how many car or plane trips are taken (in Germany the average is 1,000 car trips per year, likely close to what it is in US/Canada or Western Europe). On a single passenger per km travel basis, the plane trip is the winner (or, I should say, loser), not only because of the CO2 in the fuel emissions but also as a result of contrails which impact the climate. Travel in a small car with 3 or more passengers has less impact per passenger on the climate than rail or bus public transit which, otherwise, win.

The biggest issue for transit is passenger occupancy – they work best when full to capacity but usually they are not which leaves a heavy vehicle, wasting fuel to carry a few passengers. I’d bet on a small electric  robot car, wouldn’t you?

travel ghg  

Key Quotes:

“The climate impact from a long-distance trip can easily vary by a factor of 10 per passenger depending on mode choice, vehicle efficiency, and occupancy”

“[in Germany]Car and air travel are responsible for about 90% of the climate impact. Air travel has a higher specific climate impact per person kilometer, but after adjusting for travel volumes, the split between car and air travel is equal.”

“The climate impact of air travel is almost doubled due to the additional impact from contrail formation”.

“The climate impact from the highest income group is 250% larger than from the lowest income group. However, the middle classes account for more than two thirds of the total impact. The relatively few trips beyond 100 km contribute more than half of the total impact because of the trip distance and use of aircraft.”

“Two inner-European trips by aircraft can equal the climate impact from a whole year's driving,”

“One long-distance holiday return trip has the same impact as more than two months of regular urban travel…Likewise, a medium distance leisure round trip has the same impact as 7 days of regular urban travel”

“the climate impact from a long-distance trip (500–1,000 km, or 310–621 miles) can easily vary by a factor of 10 per passenger depending on mode choice, vehicle efficiency, and occupancy”

“The impact from short-lived climate forcers (SLCFs) and notably of contrails and cirrus clouds is particularly strong for aircraft; as a result, their specific climate impacts are strongly influenced by the choice of metric and time horizon. …Cirrus clouds and contrails contribute more than four-fifths of extra warming”
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Wednesday, February 19, 2014

Solving Congestion Problems in China’s Biggest Cities

 A big reason Beijing is polluted: The average car goes 7.5 miles per hour( Gwynn Guilford, Quartz, Jan. 3, 2014)

Also discussed here: China's Urban Nightmare: Gridlock(The Wall Street Journal, Jan. 2, 2014) Also here: Spatial and Social Characteristics of Urban Transportation in Beijing(9 page pdf, Jiawen Yang, Transportation Research Record: Journal of the Transportation Research Board,2010)

Today we review a report that compares the degree of traffic congestion in Beijing and Wuhan with large western cities that have similar trends on the growth of car ownership (and urban road building) with GDP and with the degree to which congestion has strangled traffic flows to a point where drivers in Beijing average only 12 kph. Interesting that Wuhan implemented a congestion pricing system in 2011 while more progressive cities such as New York City have failed to proceed with it as one of the most effective ways of reducing urban congestion.

Also interesting that Beijing’s twin city in Canada shares an almost identical ratio of km road lanes to urban area (of about 3-4 to 1), an indicator of poor urban transportation design (Ottawa also lacks modern Light Rail Transit, depending only on buses and planning to get a basic LRT system in the next 10-15 years).

  road density  

Key Quotes:

“The increase in automobile ownership in relation to the growth in China’s gross domestic product is similar to that in the United States, South Korea, Japan, and Germany.”

“Beijing and the southern boomtown of Shenzhen were second only to Mexico City in terms of commuter misery…Beijing hosts more than 10 million residents at its core built-up area, which is served by the five ring roads and other connecting roads.”

“about two years ago Wuhan became the first Chinese city to charge electronic tolls to reach its bustling downtown area, joining more-global cities such as London and Singapore.”

“Wuhan introduced its electronic toll-collecting system in 2011. It uses a transponder people carry in their cars, enabling their accounts to be automatically charged. The system charges at least eight yuan (about $1.30) for every use of the bridges and the tunnel. Alternatively, they can buy an annual card for unlimited usage. Bus and taxi drivers are charged 500 yuan a year, while private individual drivers pay 2,400 yuan.”

“premature death caused by traffic congestion will cost the US at least $13 billion in 2020 and $17 billion by 2030, in 2007 dollars. And that toll is clearly higher in cities like Los Angeles, where cars are de rigeur. LA incurred more than $3 billion in pollution-related mortality costs in 2010—much greater than Boston’s $125-or-so million,”
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