Dataset Information

Understanding urbanization: A study of census and satellite-derived urban classes in the United States, 1990-2010.

ABSTRACT: Most of future population growth will take place in the world's cities and towns. Yet, there is no well-established, consistent way to measure either urban land or people. Even census-based urban concepts and measures undergo frequent revision, impeding rigorous comparisons over time and place. This study presents a new spatial approach to derive consistent urban proxies for the US. It compares census-designated urban blocks with proxies for land-based classifications of built-up areas derived from time-series of the Global Human Settlement Layer (GHSL) for 1990-2010. This comparison provides a new way to understand urban structure and its changes: Most land that is more than 50% built-up, and people living on such land, are officially classified as urban. However, 30% of the census-designated urban population and land is located in less built-up areas that can be characterized as mainly suburban and peri-urban in nature. Such insights are important starting points for a new urban research program: creating globally and temporally consistent proxies to guide modelling of urban change.

SUBMITTER: Balk D

PROVIDER: S-EPMC6306171 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature

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Understanding urbanization: A study of census and satellite-derived urban classes in the United States, 1990-2010.

Balk Deborah D Leyk Stefan S Jones Bryan B Montgomery Mark R MR Clark Anastasia A

PloS one 20181226 12

Most of future population growth will take place in the world's cities and towns. Yet, there is no well-established, consistent way to measure either urban land or people. Even census-based urban concepts and measures undergo frequent revision, impeding rigorous comparisons over time and place. This study presents a new spatial approach to derive consistent urban proxies for the US. It compares census-designated urban blocks with proxies for land-based classifications of built-up areas derived f ...[more]

PMID: 30586443

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Project description:ImportanceLittle is known about recent trends in rural-urban disparities in youth suicide, particularly sex- and method-specific changes. Documenting the extent of these disparities is critical for the development of policies and programs aimed at eliminating geographic disparities.ObjectiveTo examine trends in US suicide mortality for adolescents and young adults across the rural-urban continuum.Design, setting, and participantsLongitudinal trends in suicide rates by rural and urban areas between January 1, 1996, and December 31, 2010, were analyzed using county-level national mortality data linked to a rural-urban continuum measure that classified all 3141 counties in the United States into distinct groups based on population size and adjacency to metropolitan areas. The population included all suicide decedents aged 10 to 24 years.Main outcomes and measuresRates of suicide per 100,000 persons.ResultsAcross the study period, 66,595 youths died by suicide, and rural suicide rates were nearly double those of urban areas for both males (19.93 and 10.31 per 100,000, respectively) and females (4.40 and 2.39 per 100,000, respectively). Even after controlling for a wide array of county-level variables, rural-urban suicide differentials increased over time for males, suggesting widening rural-urban disparities (1996-1998: adjusted incidence rate ratio [IRR], 0.98; 2008-2010: adjusted IRR, 1.19; difference in IRR, P = .02). Firearm suicide rates declined, and the rates of hanging/suffocation for both males and females increased. However, the rates of suicide by firearm (males: 1996-1998, 2.05; and 2008-2010: 2.69 times higher) and hanging/suffocation (males: 1996-1998, 1.24; and 2008-2010: 1.63 times higher) were disproportionately higher in rural areas, and rural-urban differences increased over time (P = .002 for males; P = .06 for females).Conclusions and relevanceSuicide rates for adolescents and young adults are higher in rural than in urban communities regardless of the method used, and rural-urban disparities appear to be increasing over time. Further research should carefully explore the mechanisms whereby rural residence might increase suicide risk in youth and consider suicide-prevention efforts specific to rural settings.

Project description:BackgroundFew studies have investigated air pollution exposure disparities by race/ethnicity and income across criteria air pollutants, locations, or time.ObjectiveThe objective of this study was to quantify exposure disparities by race/ethnicity and income throughout the contiguous United States for six criteria air pollutants, during the period 1990 to 2010.MethodsWe quantified exposure disparities among racial/ethnic groups (non-Hispanic White, non-Hispanic Black, Hispanic (any race), non-Hispanic Asian) and by income for multiple spatial units (contiguous United States, states, urban vs. rural areas) and years (1990, 2000, 2010) for carbon monoxide (CO), nitrogen dioxide (NO2), ozone (O3), particulate matter with aerodynamic diameter ≤2.5μm (PM2.5; excluding year-1990), particulate matter with aerodynamic diameter ≤10μm (PM10), and sulfur dioxide (SO2). We used census data for demographic information and a national empirical model for ambient air pollution levels.ResultsFor all years and pollutants, the racial/ethnic group with the highest national average exposure was a racial/ethnic minority group. In 2010, the disparity between the racial/ethnic group with the highest vs. lowest national-average exposure was largest for NO2 [54% (4.6 ppb)], smallest for O3 [3.6% (1.6 ppb)], and intermediate for the remaining pollutants (13%-19%). The disparities varied by U.S. state; for example, for PM2.5 in 2010, exposures were at least 5% higher than average in 63% of states for non-Hispanic Black populations; in 33% and 26% of states for Hispanic and for non-Hispanic Asian populations, respectively; and in no states for non-Hispanic White populations. Absolute exposure disparities were larger among racial/ethnic groups than among income categories (range among pollutants: between 1.1 and 21 times larger). Over the period studied, national absolute racial/ethnic exposure disparities declined by between 35% (0.66μg/m3; PM2.5) and 88% (0.35 ppm; CO); relative disparities declined to between 0.99× (PM2.5; i.e., nearly zero change) and 0.71× (CO; i.e., a ∼29% reduction).DiscussionAs air pollution concentrations declined during the period 1990 to 2010, absolute (and to a lesser extent, relative) racial/ethnic exposure disparities also declined. However, in 2010, racial/ethnic exposure disparities remained across income levels, in urban and rural areas, and in all states, for multiple pollutants. https://doi.org/10.1289/EHP8584.

Dataset Information

Understanding urbanization: A study of census and satellite-derived urban classes in the United States, 1990-2010.

Publications

Understanding urbanization: A study of census and satellite-derived urban classes in the United States, 1990-2010.

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