Wednesday, December 09, 2009
Photo by Kamshots.
With the world's leaders currently meeting in Copenhagen to discuss strategies to reduce climate change, one of the world's most prestigious medical journals, The Lancet, has released a series examining the public health benefits of various strategies aimed at reducing greenhouse gas emissions. One of these papers focuses on the impact of widespread adoption of active transportation, and the estimated public health benefit is nothing short of astonishing.
In the article titled Public Heath Benefits of Strategies to Reduce Greenhouse-Gas Emissions: Urban Land Transport, Paul Wilkinson and colleagues calculated the estimated changes in morbidity and mortality if there were to be widespread adoption of low carbon-emission vehicles, widespread adoption of active transportation, or a combination of the two. Low carbon-emission vehicles were defined as those emitting roughly half of the average vehicle today (95 g/km CO2 for cars compared with 177 g/km at present), while the level of active transportation that was analyzed was similar to that seen in continental European cities such as Copenhagen, Amsterdam, and Freiburg. Outcomes were morbidity and mortality related to changes in physical activity, air pollution, and the risk of traffic injury, and the calculations focused on London, England, and Delhi, India.
So, what did the authors find? In comparison to continuing on with "business as usual", substantially increasing active transportation by 2030 (either alone or in concert with reductions in vehicle carbon-emissions) is estimated to result in dramatic reductions in both morbidity and mortality. Due to increased physical activity alone, increased active transportation is estimated to result in a reduction of 352 premature deaths per million people per year, as well as 6040 less years of life lost, and 816 years lost due to disability in Delhi, India. In London, increasing active transportation to levels seen in Copenhagen would result in 528 less deaths per million people per year, as well as 5496 less years of life lost, and 2245 less years lost due to disability. These reductions were related to lowered prevalence of heart disease (by up to 19% in London and 25% in Delhi), cerebrovascular disease (18% in London and 25% in Delhi), dementia (8% in London), depression (6% in London), diabetes (17% in Delhi), and breast cancer (13% in London) - all diseases which are negatively associated with physical activity.
In addition to the benefits seen as a result of increased physical activity, there are also estimated reductions in morbidity and mortality as a result of lowered air pollution in both cities. While increased active transportation is expected to reduce the overall number of fatalities related to traffic crashes in Delhi by 67 per million people per year, there is an estimated increase of 11 fatalities per million per year in London. On the whole, simply increasing active transportation could reduce fatalities by 511 per million inhabitants per year in Delhi, and 530 per million inhabitants in London.
Now this type of study is obviously very speculative (and the mathematical models they used are complicated to say the least!). But I think it serves as a nice jumping-off point for a discussion of the ways that increased active transportation and other simple strategies can dramatically improve the health of our societies. Even minor reductions in morbidity and mortality could save our health care systems (and us taxpayers) and load of money, not to mention increasing the quality of life of our friends and family. Once a chronic disease like breast cancer or diabetes is present, it can be extremely costly to treat. Increasing active transportation might be a simple way to increase the health of our communities, our environment, and our wallets.
What do you think about The Lancet's estimates?
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Wilkinson, P., Smith, K., Davies, M., Adair, H., Armstrong, B., Barrett, M., Bruce, N., Haines, A., Hamilton, I., & Oreszczyn, T. (2009). Public health benefits of strategies to reduce greenhouse-gas emissions: household energy The Lancet, 374 (9705), 1917-1929 DOI: 10.1016/S0140-6736(09)61713-X
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