Cities and Suburbs
Nearly 80% of the U. S. population lives in a metropolitan area (a city plus its suburbs): half in suburbs and around 30% in central cities. This pattern of suburbanization has a complex history of in-migration and urban-flight and was powered by population and economic growth. The largest of the metropolitan areas is the New York City Metropolitan area, which spreads out over 4 states (NY, NJ, CN, PA) and contains over 21 million people. (U.S. 2000 Census)
Photo: EPA
In many cities and suburbs a car is required for almost every activity. Commuters spend hours in congested traffic, parents drive their children from activity to activity, the elderly and disabled have to rely on relatives, social services, or taxis to leave their homes.
AIR POLLUTION
Exposure to pollutants such as ozone and airborne fine particulate matter has been correlated with increases in daily mortality rates and with hospital admissions for respiratory and cardiovascular disease. (Link from here TO Air Pollution health effects) This kind of air pollution is a feature of many urban environments. Its two largest sources are vehicular traffic and power generation.
On average people drive around 30 miles a day, a trend that from 1950 has been steadily increasing at a rate of 0.4 miles a year. The resulting vehicle exhaust contributes to a variety of respiratory and circulatory ailments, such as asthma and heart disease. Air pollution levels have been shown to be correlated with mortality, especially among people with existing cardiovascular and chronic obstructive pulmonary diseases. The elderly are another group known to be susceptible to pollution-induced mortality. (Reference 1)
AUTO ACCIDENTS
Traffic accidents and fatalities are, of course, related to vehicle use. Generally in the CARA region, the states currently all rank in the better half of the national ratings for traffic fatalities per million vehicle miles driven (with Pennsylvania and Delaware having the worst records of the group). The rankings for 2002 are shown in the following table. The trend in fatalities per mile driven have been slowly and steadily decreasing due to improvements in road safety, however, the overall number of fatalities have increased due to the increased number of miles driven.
STATE AVERAGE FATALITY RATES FOR VEHICLE ACCIDENTS
|
Fatalities per million vehicle miles |
National ranking (a rank of 1 is the worst; 50 is the best) |
| Connecticut | 1.03 |
46 |
| Delaware | 1.40 |
28 |
| Maryland | 1.23 |
39 |
| Massachusetts | 0.86 |
49 |
| New Jersey | 1.11 |
44 |
| New York | 1.14 |
43 |
| Pennsylvania | 1.54 |
25 |
| Rhode Island | 1.03 |
46 |
| Virginia | 1.18 |
42 |
| District of Colombia | 1.33 |
- |
Bureau of the Census, 2002 http://www.census.gov/statab/ranks/rank39.html
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The predicted aging of the population may have an impact on the traffic fatality rates in the coming years as more and more drivers reach the ages of 65.
| Fatality Rate by Driver Age | |
| Fatal crashes per 100 million miles driven, 1990 |
 |
http://www.luhs.org/depts/injprev/Transprt/tran3.htm
OBESITY
Almost no physical activity is required in the daily routine of many people. This favors obesity and obesity-related diseases such as Type 2 diabetes, cardiovascular disease, cancers of certain organs (colon, endometrial, post-menopausal breast, and kidney), gallbladder disease, and osteoarthritis.
http://www.cdc.gov/nccdphp/dnpa/obesity/trend/maps/476,5,Slide 5
For instance, studies in Vancouver found that each additional hour spent in a car per day increased the likelihood of being obese by 6%. (Reference 2) Furthermore, walk-friendly residential designs increase the number of people getting the recommended 30 or more minutes of physical activity per day. (Reference 3) A summary of recent research into the trends and causes of inactivity can be found in the Reference 4. Obesity is related to a number of risk factors in addition to lack of exercise. A good resource is the Centers of Disease Control and Prevention website: http://www.cdc.gov/nccdphp/dnpa/obesity/index.htm
HEALTH PROBLEMS IN INNER CITIES
Life expectancy, all-cause mortality rates and other health indicators are actually better in some urban areas than in nonurban areas. This is not true, of course, for all cities or all neighborhoods within cities. Cities typically include both wealthy and impoverished areas, so city-wide health measurements tend to obscure the variation within a city. Health indicators are uniformly worse in inner-cities and slums, and some of the ill-health is directly related to the built environment.
Conditions such as asthma, injuries, lead poisoning, and depression are more prevalent in people living in dilapidated housing. Urban design may also affect crime and violence rates. Cities with aging water and sewer infrastructure can have problems with lead, bacteria, or dirt in the drinking water, especially cash-strapped cities that don’t maintain their systems. Also, rodent populations in cities, particularly rats, can be carriers of disease. (For instance, see the section on Leptospirosis, below.)
Cities also suffer in the summer from the urban heat island effect, when temperatures rise up to 5 degrees F higher than surrounding areas, and this can lead to heat stroke and dehydration, especially among people whose homes lack air conditioning. [Link to CARA Weather Heat] (Reference 5) Heat islands are the result of reduced plant cover and the heat storing qualities of concrete and asphalt, which combine to reduce evaporative cooling and warm the surface air.
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