They use energy, breathe, and pollute

Aug 19, 2009 08:41 GMT  ·  By
Tokyo is the largest metropolis in the world, with nearly 34 million inhabitants
   Tokyo is the largest metropolis in the world, with nearly 34 million inhabitants

The concept of urban metabolism is not by far a new one. Scientists have proposed that similarities exist between the world's megacities and living organisms for a long time, but now reports on how human settlements function are drawing more and more parallels to the living world. The comparisons, experts say, may help them get a better understanding of how we influence the quality of the air in metropolises, the lives of people living around the major urban centers, as well as the global climate.

These conclusions belong to a new “urban metabolism” report, recently presented by experts at the 238th annual meeting of the American Chemical Society (ACS), held in Washington DC between August 16-18, ScienceDaily reports. “Carbon dioxide and other pollutants in megacities make them immense drivers of climate change. They impact climate on both a regional and global level because these long-lived greenhouse gases are dispersed around the world,” Charles Kolb, PhD, explains. The expert holds a double appointment at the Billerica, Massachusetts-based Aerodyne Research Inc.'s Center for Atmospheric and Environmental Chemistry and the Center for Aerosol and Cloud Chemistry.

Kolb views cities as living entities for a number of simple reasons. For instance, they consume food, energy and raw materials, just like an animal does, then it processes them for sustenance and excretes what it no longer needs. This includes carbon dioxide, the main greenhouse gas held responsible for global warming, air pollutants, sewage and other water pollutants, as well as excess heat, which also influences the surrounding environment. Parasites such as rats and various internal systems (heat, energy, supply chains, etc.) also exist, which further enhance the similarity to a living body.

But cities are also prone to experiencing the effects of their own actions, such as it's the case with Mexico City. Because of its high-altitude/low-latitude location, vast amounts of smog are produced, which remain above the city throughout the day, everyday. “That causes a very serious situation for residents of Mexico City. You get very unhealthful levels of ozone and fine particle pollutants that produce large numbers of premature deaths each year,” Kolb says.

“Studies show that for each increase of 10 micrograms per cubic meter of these particles, you get roughly a 10 percent increase in premature deaths, producing a decrease in average life expectancy of about 0.8 years. Hospital visits, including bronchitis and asthma cases, also rise,” he adds. By studying urban metabolism, Kolb shares, experts can better understand how to manage air quality, so as to keep metropolis residents out of harm's way. Cities like LA, New York and Tokyo have managed to do that to some extent, and their example could be extended to other growing cities as well.