"In this paper, we investigate the relationship between urban spatial structure and air quality in the United States. By using urban landscape metrics framework, we empirically examine whether fragmentary and sprawling urban patterns are associated with low air quality. We develop an algorithm to correct for biases within the urban landscape metrics in the United States. Controlling for demographic variables and economic activity, we find a strong relationship between the type and pattern of development and pollutant levels. The finding is not biased by the presence of relatively rural counties in the dataset suggesting that paying close attention to the urban form might have some implications for air quality".
Citation:
Joshua McCarty and Nikhil Kaza. "Urban form and air quality in the United States." Landscape and Urban Planning 139 (2015): 168–179, accessed September 23, 2015, doi:10.1016/j.landurbplan.2015.03.008.
Where do the authors work, and what are their areas of expertise? Note any other publications by the authors with relevance to the 6Cities project.
Joshua McCarty:
Department of City and Regional Planning, University of North Carolina at Chapel Hill
Different patterns in development form various types and intensities of air pollution
City planning can be modified to consciously protect their air quality.
"While urban counties tend to have higher number of days with low air quality, the mixed rural counties have a long right tail of the distribution"
More days of AQI exceedance found in urban forms with
higher temperatures
less precipitation
larger population
Industrial work
Lower median wealth
People with higher incomes are able to drive nicer cars, which have better filtration systems.
Fewer surrounding forests or vegetation
Yet, increased forest area lead to higher ozone levels
Smaller urban area
Increasing urban area while holding population constant reduces the number of days exceeding AQI desired levels
Describe at least three ways that the argument is supported.
Strong emphasis on forests/plantlife affecting urban settings and the air pollution exposure of urban dwellers.
What three (or more) quotes capture the message of the article or report?
"We find that poor air quality and urban fragmentation are related in all types of counties and not just in metropolitan regions. Using land cover data we are also able to explore the mitigating potential of forest land cover that are proximate to urban areas."
"We find that after controlling for demographic factors and the level of urbanization, both the pattern of urbanization and the mixing of different land cover types are important correlates of pollutant levels and air quality. Public action for mitigating pollutant levels could refer to land use strategies in addition to other emission control mechanisms."
"If a fragmentary pattern of urban development must be pursued, preserving the forested areas would help mitigate the pollutants."
What were the methods, tools and/or data used to produce the claims or arguments made in the article or report?
Studied MSA's (Metropolitan Statistical Areas), broken into counties to understand the differences of urban form within a city (like large NYC)
Air quality data source
EPA AQI values of ozone and PM2.5
if multiple monitors in one county, used the maximum AQI value
averaged the annual number of days above the NAAQS limit from 2004-2008
Compared urban/rural and mixed average annual days of exceeding
For "overall air quality" used EPA reports of number of days of incompliance of counties for CO, NO2, O3, SO2, PM2.5, PM10. The daily average AQI was the AQI of the pollutant with the highest concentration.
Urban Landscape metrics
Used landcover satellite data
Sources have data on urban and rural communities. Continuous surveying is an option.
Can study the interactions and mixing of various land covers (e.g. the impact of nearby tree cover on urban air quality)
Does not rely on only population socioeconomic data, when these things change during urbanization
"metrics that are characterized only by demographic and economic variables at any given time are less likely to capture the phase difference between urban land conversion and economic and demographic changes in a place
Identified urban land cover and forest cover
Established urban form metrics (metrics described in image below)
The metrics were adjusted for transportation/types of roads used and fragmenting of the urban area.
Calculated area of forest within 1 km buffer around the "urban patch"
Statistical models
"To correct for the spatial autocorrelation bias, we use spatial econometric models"
"where Y is the dependent variable (number of AQI exceedances), X is the set of independent variables (urban form metrics as well as control variables), and is the spatial component of the error term. W is the spatial weights matrix that is reflective of the spatial interaction"
The expected type of correlation between AQI and each metric studied.
How (if at all) are health disparities or other equity issues addressed in the article or report?
Health disparities are not addressed in the report.
Where has this article or report been referenced or discussed? (In some journals, you can see this in a sidebar.)
This article has been very recently published. I was unable to find anywhere it has been discussed.
Can you learn anything from the article or report’s bibliography that tells us something about how the article or report was produced?
Sources on air pollution and urban development, statistics methods, urban sprawl.
Mostly US specific sources, one from China
Work was done according to urban development in the US.
What three points, details or references from the text did you follow up on to advance your understanding of how air pollution science has been produced and used in governance and education in different settings?
The study describes types of urban forms and their relationship with air pollution. I looked further into that.
"Regions that urbanized earlier in the century (Boston, Chicago, New York, etc.) are more contiguous while regions that have urbanized later in the century (Phoenix, Houston, Raleigh, etc.) exhibit fragmentary development"
"Although there is a correlation between development and air quality, population and urban land area alone are not sufficient for explaining the exceedances. The most populated counties in the nation are not the ones which experience the most exceedances nor do the counties with the largest urban area necessarily experience worse air quality."
I attempted to find the type of urban form that Philadelphia, PA is.
- Abstract:
"In this paper, we investigate the relationship between urban spatial structure and air quality in the United States. By using urban landscape metrics framework, we empirically examine whether fragmentary and sprawling urban patterns are associated with low air quality. We develop an algorithm to correct for biases within the urban landscape metrics in the United States. Controlling for demographic variables and economic activity, we find a strong relationship between the type and pattern of development and pollutant levels. The finding is not biased by the presence of relatively rural counties in the dataset suggesting that paying close attention to the urban form might have some implications for air quality".- Citation:
Joshua McCarty and Nikhil Kaza. "Urban form and air quality in the United States." Landscape and Urban Planning 139 (2015): 168–179, accessed September 23, 2015, doi:10.1016/j.landurbplan.2015.03.008.Where do the authors work, and what are their areas of expertise? Note any other publications by the authors with relevance to the 6Cities project.
- Joshua McCarty:
- Department of City and Regional Planning, University of North Carolina at Chapel Hill
- Expertise: Geo-Accounting
- "His work focuses on the intersection of public policy, urban design, and economics" (http://www.urban-three.com/joshua-mccarty/)
- Publications:
- How the way we build cities and communities affects the quality of the air that we breathe
- Other work:
- Urban3: An urban planning firm
- http://www.urban-three.com/
- Nikhil Kaza:
- Department of City and Regional Planning, University of North Carolina at Chapel Hill
- Expertise: Urban Planning
- Publications:
- Same as Joshua McCarty
What are the main findings or arguments presented in the article or report?- Urban development trends on air pollution
- Scattered lead to greater automobile emissions
- "impervious surface cover" leads to ozone accumulation
- Leapfrog development and pollution during construction lead to NO2
- Leapfrog development: extending from an existing development (http://definitions.uslegal.com/l/leapfrog-development/)
- Different patterns in development form various types and intensities of air pollution
- City planning can be modified to consciously protect their air quality.
- "While urban counties tend to have higher number of days with low air quality, the mixed rural counties have a long right tail of the distribution"
- More days of AQI exceedance found in urban forms with
- higher temperatures
- less precipitation
- larger population
- Industrial work
- Lower median wealth
- People with higher incomes are able to drive nicer cars, which have better filtration systems.
- Fewer surrounding forests or vegetation
- Yet, increased forest area lead to higher ozone levels
- Smaller urban area
- Increasing urban area while holding population constant reduces the number of days exceeding AQI desired levels
Describe at least three ways that the argument is supported.- Strong emphasis on forests/plantlife affecting urban settings and the air pollution exposure of urban dwellers.
What three (or more) quotes capture the message of the article or report?- "We find that poor air quality and urban fragmentation are related in all types of counties and not just in metropolitan regions. Using land cover data we are also able to explore the mitigating potential of forest land cover that are proximate to urban areas."
- "We find that after controlling for demographic factors and the level of urbanization, both the pattern of urbanization and the mixing of different land cover types are important correlates of pollutant levels and air quality. Public action for mitigating pollutant levels could refer to land use strategies in addition to other emission control mechanisms."
- "If a fragmentary pattern of urban development must be pursued, preserving the forested areas would help mitigate the pollutants."
What were the methods, tools and/or data used to produce the claims or arguments made in the article or report?- Studied MSA's (Metropolitan Statistical Areas), broken into counties to understand the differences of urban form within a city (like large NYC)
- Air quality data source
- EPA AQI values of ozone and PM2.5
- if multiple monitors in one county, used the maximum AQI value
- averaged the annual number of days above the NAAQS limit from 2004-2008
- Compared urban/rural and mixed average annual days of exceeding
- For "overall air quality" used EPA reports of number of days of incompliance of counties for CO, NO2, O3, SO2, PM2.5, PM10. The daily average AQI was the AQI of the pollutant with the highest concentration.
- Urban Landscape metrics
- Used landcover satellite data
- Sources have data on urban and rural communities. Continuous surveying is an option.
- Can study the interactions and mixing of various land covers (e.g. the impact of nearby tree cover on urban air quality)
- Does not rely on only population socioeconomic data, when these things change during urbanization
- "metrics that are characterized only by demographic and economic variables at any given time are less likely to capture the phase difference between urban land conversion and economic and demographic changes in a place
- Identified urban land cover and forest cover
- Established urban form metrics (metrics described in image below)
- The metrics were adjusted for transportation/types of roads used and fragmenting of the urban area.
- Calculated area of forest within 1 km buffer around the "urban patch"
- Statistical models
- "To correct for the spatial autocorrelation bias, we use spatial econometric models"
- "where Y is the dependent variable (number of AQI exceedances), X is the set of independent variables (urban form metrics as well as control variables), and is the spatial component of the error term. W is the spatial weights matrix that is reflective of the spatial interaction"
- The expected type of correlation between AQI and each metric studied.
How (if at all) are health disparities or other equity issues addressed in the article or report?- Health disparities are not addressed in the report.
Where has this article or report been referenced or discussed? (In some journals, you can see this in a sidebar.)- This article has been very recently published. I was unable to find anywhere it has been discussed.
Can you learn anything from the article or report’s bibliography that tells us something about how the article or report was produced?- Sources on air pollution and urban development, statistics methods, urban sprawl.
- Mostly US specific sources, one from China
- Work was done according to urban development in the US.
What three points, details or references from the text did you follow up on to advance your understanding of how air pollution science has been produced and used in governance and education in different settings?