Emerging urban form – Emerging pollution: Modelling endogenous health and environmental effects of traffic on residential choice

in Environment and Planning B (2018)

Air pollution bears severe health and environmental impacts and is of increasing concern to urban planners but densification strategies have ambiguous impacts. We analyse how households’ aversion to ... [more ▼]

Air pollution bears severe health and environmental impacts and is of increasing concern to urban planners but densification strategies have ambiguous impacts. We analyse how households’ aversion to generating and being exposed to traffic pollution at the residential place and during their commute influences emerging urban structures and how these structures in turn affect pollution exposure and the residential choice of households. Resulting spatial patterns are difficult to predict because of this feedback and the spatial form of urbanisation and road networks. We address this complexity with a micro-economic agent-based residential choice model dynamically coupled with a cellular automata model for pollution dispersion and its perception in neighbourhoods. Our simulation experiments on a theoretical grid suggest that the spatial scale of this perception is important. We also find that if both health and environmental concerns are to be addressed, a combination of reducing commuting distances and preserving local green spaces is necessary. In particular, locally dispersed urban development and intra-urban green spaces next to busy roads can mitigate pollution exposure. [less ▲]

Equilibrium and first-best city with endogenous exposure to local air pollution from traffic

in Regional Science and Urban Economics (2017), 62

Exposure to urban traffic-induced air pollution is a major health concern of cities. This paper analyzes the urban structure when localized pollution exposure arises from commuting traffic and ... [more ▼]

Exposure to urban traffic-induced air pollution is a major health concern of cities. This paper analyzes the urban structure when localized pollution exposure arises from commuting traffic and investigates the feedback effect of endogenous pollution on residential choices. The presence of stronger traffic-induced air pollution exposure reduces the geographical extent and the population of cities. Land rents fall with distance from the city center while population densities may be non-monotonic. Cleaner vehicle technologies reduce pollution exposure everywhere, increase population and density everywhere and do not affect the spatial extent of the city. The paper compares the urban equilibrium with the first-best. The first-best structure is a less expanded city with higher densities at the center and lower densities at the fringe. [less ▲]

Spatial modelling of feedback effects between urban structure and traffic-induced air pollution - Insights from quantitative geography and urban economics

Doctoral thesis (2016)

Urban air pollution is among the largest environmental health risk and its major source is traffic, which is also the main cause of spatial variation of pollution concerns within cities. Spatial responses ... [more ▼]

Urban air pollution is among the largest environmental health risk and its major source is traffic, which is also the main cause of spatial variation of pollution concerns within cities. Spatial responses by residents to such a risk factor have important consequences on urban structures and, in turn, on the spatial distribution of air pollution and population exposure. These spatial interactions and feedbacks need to be understood comprehensively in order to design spatial planning policies to mitigate local health effects. This dissertation focusses on how residents take their location decisions when they are concerned about health effects associated with traffic-induced air pollution and how these decisions shape future cities. Theoretical analytical and simulation models integrating urban economics and quantitative geography are developed to analyse and simulate the feedback effect between urban structure and population exposure to traffic-induced air pollution. Based on these, spatial impacts of policy, socio-economic and technological frameworks are analysed. Building upon an empirical exploratory analysis, a chain of theoretical models simulates in 2D how the preference of households for green amenities as indirect appraisal of local air quality and local neighbourhood design impact the environment, residents' health and well-being. In order to study the feedback effect of households' aversion to traffic-induced pollution exposure on urban structure, a 1D theoretical urban economics model is developed. Feedback effects on pollution and exposure distributions and intra-urban equity are analysed. Equilibrium, first- and second-best are compared and discussed as to their population distributions, spatial extents and environmental and health implications. Finally, a dynamic agent-based simulation model in 2D further integrates geographical elements into the urban economics framework. Thus, it enhances the spatial representation of the spatial interactions between the location of households and traffic-induced air pollution within cities. Simulations contrast neighbourhood and distance effects of the pollution externality and emphasise the role of local urban characteristics to mitigate population exposure and to consolidate health and environmental effects. The dissertation argues that the consideration of local health concerns due to traffic-induced air pollution in policy design challenges the concept of high urban densification both locally and with respect to distance and advises spatial differentiation. [less ▲]

Equilibrium and first-best city with endogenous exposure to local air pollution from traffic

E-print/Working paper (2016)

Exposure to urban traffic-induced air pollution is a major health concern of cities. This paper analyzes the urban structure when localized pollution exposure arises from commuting traffic and ... [more ▼]

Exposure to urban traffic-induced air pollution is a major health concern of cities. This paper analyzes the urban structure when localized pollution exposure arises from commuting traffic and investigates the feedback effect of endogenous pollution on residential choices. The presence of stronger traffic-induced air pollution exposure reduces the geographical extent and the population of cities. Land rents fall with distance from the city center while population densities may be non-monotonic. Cleaner vehicle technologies reduce pollution exposure everywhere, increase population and density everywhere and do not affect the spatial extent of the city. The paper compares the urban equilibrium with the first-best. The first-best structure is a less expanded city with higher densities at the center and lower densities at the fringe. [less ▲]

Exposition gegenüber verkehrsbedingter Luftverschmutzung und Gerechtigkeit - eine innerstädtische Analyse mithilfe eines Residential Choice Models

Poster (2015, October)

Traffic-induced air pollution concerns and policy design – Impact analysis on urban structure and distance-related exposure equity

Scientific Conference (2015, July 02)

Traffic-induced air pollution causes environmental and health concerns, which affect households differently depending on where they live within the city. The intra-urban distribution of households might ... [more ▼]

Traffic-induced air pollution causes environmental and health concerns, which affect households differently depending on where they live within the city. The intra-urban distribution of households might be more concentrated on central locations to reduce emissions if households are environmentally conscious, while a city of households who value local air quality in residential choice tends to be more dispersed to mitigate population exposure (e.g. Robson, 1976). Contrasting these two preferences raises questions of equity as to how much each household causes other residents to be exposed to air pollution and how much each household is itself affected by the location choice of others. This relative assessment, in turn, could influence households’ perception of air pollution at their residential location, which is subject to several psychological processes (Gatersleben & Uzzell 2000). The equity concern as a result of households’ perception and valuation of local air quality and of different urban policies is the focus of this work. Some research has been conducted on the effects of urban structure on the environment in terms of emissions (e.g. Verhoef & Nijkamp, 2003; Stone et al., 2007), and on the exposure of households living at different locations in the city (e.g. Schweitzer & Zhou, 2010). However, few have contrasted both perspectives within the city (e.g. Martins, 2012; Schindler & Caruso, 2014) or analysed distance-related equity concerns arising from traffic-induced air pollution in this context (e.g. Ridder et al., 2008). This work aims at investigating the effects of different policy approaches on the two-way interactions between the location of households and the distribution of pollution and, thus, on intra-urban exposure-related equity ratios. This work contributes to theoretical research by presenting an extension to the standard urban economics model by endogenous local pollution externalities arising from passing traffic, which has been analytically solved for equilibrium in a closed city framework. Comparative statics are performed which serve as impact analysis of various policy designs on intra-urban structure and equity ratios, such as technological improvements of vehicles and urban growth boundaries. Further, the model is adapted for optimum city where local pollution externalities are internalized through optimum distance-related toll levels. Finally, the work compares the effects of equilibrium and optimum city structure on equity ratios. [less ▲]

Spatial implications of endogenous pollution externalities in a residential location model

Scientific Conference (2014, August)

Exposure to traffic-induced air pollution is acknowledged to cause harmful effects on the environment and human health. Citizens are increasingly concerned as reflected in the willingness of citizens to ... [more ▼]

Exposure to traffic-induced air pollution is acknowledged to cause harmful effects on the environment and human health. Citizens are increasingly concerned as reflected in the willingness of citizens to pay for living in less polluted urban environments. Air quality is an amenity progressively considered in location choice . While residents might seek to remove oneself from traffic as source of emissions and favour low density environments, urban planners often argue towards urban densification in order to limit the generation of emissions by reducing distances between activities and, thus, distances travelled . The potential ease of citizens’ satisfaction in such densified areas with reduced green space amenities and concentration of development and traffic is, however, often omitted . This contradiction triggers the debate about the role of urban structure and, in particular, residential preferences on mitigating not only environmental, but also health and social impacts caused by urban air pollution. To shed further light on this debate, we contribute a spatial economics model focussing on residential choice and explicitly including traffic-induced exposure to air pollution as residential disamenity. Economic literature introducing air pollution on an urban scale into economic models to assess its impact on urban structure comprises equilibrium models with aggregate pollution from industrial sources ; however, only few with (disaggregate) pollution from transport and an explicit treatment of space . A general link between environmental and traffic congestion externalities has been mathematically formalized but not yet explicitly so in the context of residential exposure. This research builds on the standard urban economics model and explicitly formulates exposure disamenities in residents’ utility perception. The paper focuses on deriving analytical properties from the model with pollution exposure from traffic, while the literature is predominantly numerical so far. Analytical comparative statics grant insights into spatial implications, residents’ utility and health impacts. Thereby, also the impact of, for instance, environmental awareness, technological improvements and the severity of health damage are analysed. Despite vast critiques on sprawl, with regard to air pollution dispersed urban structures resulting from exposure aversion might yet reflect beneficial trade-offs between commuting distance and prevention of exposure; thus, between environmental and social concerns. [less ▲]

Modelling dynamic urban structures and air pollution exposure

Scientific Conference (2013, September)

Despite vast technological improvements and various political control strategies, air pollution is a major concern in urban areas worldwide. Hereby, traffic is acknowledged to be the major source. Several ... [more ▼]

Despite vast technological improvements and various political control strategies, air pollution is a major concern in urban areas worldwide. Hereby, traffic is acknowledged to be the major source. Several studies provide evidence for the influence of travel behaviour and other characteristics on air pollution (e.g. Briggs et al., 2008) and research is increasingly expanding this link by investigating which role urban form plays in the discussion about sustainable cities (Jabareen, 2006). In order to meet sustainable growth, many argue that a compact city is the desirable urban form due to shorter travelling distances and reduced conversion of land, just in contrast to the trend towards urban sprawl (e.g. Stone et al., 2007). However, if energy consumption (Newman & Kenworthy, 2000) and total emissions (Cervero, 2000) can be shown to be reduced with more compact urban forms via reduced car use at regional scale, compactness is still debated (Gordon & Richardson, 1997). Residents often respond to externalities such as pollution primarily through spatial behaviour (location and relocation choices) which may have important impacts on the emerging form of cities. As these forms may not be socially optimal and are currently widely debated, there is a need for further research on welfare-enhancing policies. The question I ask is: if preferences such as exposure to car-related air pollution and the valuation of green space are considered by residents in their choice of residential location, which role do they play in shaping our cities and in overcoming the environmental and social challenge? In order to investigate this, I compare two approaches: first, a simulation approach by developing a system comprising five spatio-dynamic models; second, a micro-economic urban growth modelling approach considering residential preferences. Opposing the simulation to a further simplified model emanating from micro-economic principles provokes the discussion on complexity versus simplicity in urban modelling. The simulation method allows to a) model the growth of an urban area (Caruso et al. (2010), b) model the traffic flow which would be generated by residents commuting on the resulting road network, c) estimate the emissions generated, d) model how these emissions are dispersed by wind and finally e) estimate the average exposure residents are faced with at each residential location. In contrast, the micro-economic approach models residential location in a peri-urban area in mono-centric one-dimensional space. Inspired by works from e.g. Fujita (1989), Arnott et al. (2008), Gubins & Verhoef (2012) and Franceschetti et al. (2013) I aim at complementing existing urban equilibrium models by linking air pollution exposure and traffic congestion externalities with spatiality and residential valuations. Through contrasting the two approaches I take on the discussion of complexity in urban environmental modelling and investigate how policy interactions impact on intra-urban forms and the well-being of residents. [less ▲]

On MAUP, neighbourhood definitions and the measure of urban sprawl

Scientific Conference (2013)

On the impacts of transport policies and urban form on traffic-induced air pollution (extended abstract)

in Hesse, Markus; Caruso, Geoffrey; Gerber, Philippe (Eds.) et al Proceedings of the BIVEC-GIBET Transport Research Days 2013 (2013)

Air pollution is a major concern in urban areas worldwide. It is not only a hazard to the environment but also on human health. Many argue that a compact city is the desirable urban form in the context of ... [more ▼]

Air pollution is a major concern in urban areas worldwide. It is not only a hazard to the environment but also on human health. Many argue that a compact city is the desirable urban form in the context of sustainability due to shorter travelling distances and reduced conversion of land. If considering not only the environmental pillar of sustainability in terms of total emissions but also the social one comprising human exposure and social well-being, the argumentation might change. The question we ask is whether selected common transport policies are efficient solutions to overcome the environmental and social challenge? In order to investigate this question, we developed a modelling system in order to test the impacts of different transport policies, either on the urban structure itself or on traffic flows and respectively on air quality. [less ▲]