@article{BorckSchrauth2020,
  author    = {Borck, Rainald and Schrauth, Philipp},
  title     = {Population density and urban air quality},
  series = {Regional science and urban economics},
  volume    = {86},
  journal   = {Regional science and urban economics},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0166-0462},
  doi       = {10.1016/j.regsciurbeco.2020.103596},
  pages     = {24},
  year      = {2020},
  abstract  = {We use panel data from Germany to analyze the effect of population density on urban air pollution (nitrogen oxides, particulate matter, ozone, and an aggregate index for bad air quality [AQI]). To address unobserved heterogeneity and omitted variables, we present long difference/fixed effects estimates and instrumental variables estimates, using historical population and soil quality as instruments. Using our preferred estimates, we find that the concentration increases with density for NO2 with an elasticity of 0.25 and particulate matter with elasticity of 0.08. The O-3 concentration decreases with density with an elasticity of -0.14. The AQI increases with density, with an elasticity of 0.11-0.13. We also present a variety of robustness tests. Overall, the paper shows that higher population density worsens local air quality.},
  language  = {en}
}
@article{GudipudiFluschnikRosetal.2016,
  author    = {Gudipudi, Venkata Ramana and Fluschnik, Till and Ros, Anselmo Garcia Cantu and Walther, Carsten and Kropp, J{\"u}rgen},
  title     = {City density and CO2 efficiency},
  series = {Energy policy : the international journal of the political, economic, planning, environmental and social aspects of energy},
  volume    = {91},
  journal   = {Energy policy : the international journal of the political, economic, planning, environmental and social aspects of energy},
  publisher = {Elsevier},
  address   = {Oxford},
  issn      = {0301-4215},
  doi       = {10.1016/j.enpol.2016.01.015},
  pages     = {352 -- 361},
  year      = {2016},
  abstract  = {Cities play a vital role in the global climate change mitigation agenda. City population density is one of the key factors that influence urban energy consumption and the subsequent GHG emissions. However, previous research on the relationship between population density and GHG emissions led to contradictory results due to urban/rural definition conundrum and the varying methodologies for estimating GHG emissions. This work addresses these ambiguities by employing the City Clustering Algorithm (CCA) and utilizing the gridded CO2 emissions data. Our results, derived from the analysis of all inhabited areas in the US, show a sub-linear relationship between population density and the total emissions (i.e. the sum of on-road and building emissions) on a per capita basis. Accordingly, we find that doubling the population density would entail a reduction in the total CO2 emissions in buildings and on-road sectors typically by at least 42\%. Moreover, we find that population density exerts a higher influence on on-road emissions than buildings emissions. From an energy consumption point of view, our results suggest that on-going urban sprawl will lead to an increase in on-road energy consumption in cities and therefore stresses the importance of developing adequate local policy measures to limit urban sprawl. (C) 2016 Elsevier Ltd. All rights reserved.},
  language  = {en}
}