Department of Civil Engineering, University of Minnesota, Minneapolis, Minnesota 55455, USA.
Environ Sci Technol. 2011 Jun 1;45(11):4914-9. doi: 10.1021/es103866b. Epub 2011 May 4.
Urban air pollution is among the top 15 causes of death and disease worldwide, and a problem of growing importance with a majority of the global population living in cities. A important question for sustainable development is to what extent urban design can improve or degrade the environment and public health. We investigate relationships between satellite-derived estimates of nitrogen dioxide concentration (NO(2), a key component of urban air pollution) and urban form for 83 cities globally. We find a parsimonious yet powerful relationship (model R(2) = 0.63), using as predictors population, income, urban contiguity, and meteorology. Cities with highly contiguous built-up areas have, on average, lower urban NO(2) concentrations (a one standard deviation increase in contiguity is associated with a 24% decrease in average NO(2) concentration). More-populous cities tend to have worse air quality, but the increase in NO(2) associated with a population increase of 10% may be offset by a moderate increase (4%) in urban contiguity. Urban circularity ("compactness") is not a statistically significant predictor of NO(2) concentration. Although many factors contribute to urban air pollution, our findings suggest that antileapfrogging policies may improve air quality. We find that urban NO(2) levels vary nonlinearly with income (Gross Domestic Product), following an "environmental Kuznets curve"; we estimate that if high-income countries followed urban pollution-per-income trends observed for low-income countries, NO(2) concentrations in high-income cities would be ∼10× larger than observed levels.
城市空气污染是全球排名前 15 的死亡和疾病原因之一，也是一个随着大多数全球人口居住在城市而变得日益重要的问题。可持续发展的一个重要问题是城市设计在多大程度上可以改善或恶化环境和公共健康。我们研究了全球 83 个城市的卫星衍生氮氧化物浓度（NO2，城市空气污染的一个关键组成部分）与城市形态之间的关系。我们发现，使用人口、收入、城市连续性和气象学作为预测因子，可以建立一个简洁而强大的关系（模型 R2=0.63）。城市中具有高度连续建成区的城市，其城市 NO2 浓度通常较低（连续性增加一个标准差与平均 NO2 浓度降低 24%相关）。人口较多的城市往往空气质量较差，但人口增加 10%所带来的 NO2 增加可能会被适度增加（4%）的城市连续性所抵消。城市的圆形（“紧凑性”）不是 NO2 浓度的统计学上显著预测因子。尽管许多因素促成了城市空气污染，但我们的研究结果表明，反跨越式政策可能会改善空气质量。我们发现，城市 NO2 水平随收入（国内生产总值）呈非线性变化，遵循“环境库兹涅茨曲线”；我们估计，如果高收入国家遵循低收入国家观察到的城市污染与收入相关的趋势，高收入城市的 NO2 浓度将比观察到的水平高出约 10 倍。
