DISCUSSION
GIS is a useful tool in analyzing environmental justice. It allows us to draw links between the location of toxic polluting facilities and socio-economic conditions of neighborhoods. Wang and Feliberty (2010) study environmental justice in Cook County, Chicago, and finds that Hispanic population is the most disadvantaged group compared to other ethnic groups. Our study analyzes environmental justice in 77 community areas in Chicago and also finds the similar result. Hispanic population is the only ethnic group that suffers from the issue of environmental injustice. It is more likely to find high toxic releasing facilities in neighborhoods with high Hispanic ratios. On the other hand, not many facilities are located in neighborhoods with high Black and Asian ratios. Although there are some facilities located in community areas with high White population, the annual emission of these facilities is relatively low. Therefore, our hypothesis that high polluting facilities are found in visible-minority communities is rejected. Not all visible minority groups face environmental injustice. In Chicago, only the Hispanic or Latino population suffers from environmental degradation.
We also hypothesized that toxic releasing facilities are located in low median income communities, and this is proved. Community areas located in West Side and far Southeast Side of Chicago have the lowest median household income, and correspondingly, these are the places where toxic releasing facilities are densely located. Bullard et al. (2008) and Wang and Feliberty (2010) state this pattern as a “chicken and egg” problem due to the question of who comes first: the residences or the facilities. It is difficult to answer whether residences of a particular area are exposed to environmental hazardous due to circumstances, or the toxic releasing facilities are located purposely in these low-income neighborhoods.
Herrnstadt’s study (2016) found a positive relationship between crime and environmental pollution. He stated that the more a neighborhood exposed to pollution, the higher the crime rate. Nevertheless, our project showed a different result. In Chicago, community areas with high toxic releasing concentration have a low frequency of assault, battery, burglary and robbery, and offense. Indoor crimes tend to cluster in neighborhoods with fewer toxic releases. When we change the location setting to outdoor, crime frequency increases in Garfield and Central Chicago region, where a moderate level of toxic release is found. However, the crime frequency for community areas with the highest toxic release still remains low. All four types of crime follow this pattern. Therefore, our hypothesis that the highest crime rate corresponds with heavily polluted areas is rejected.
The crime frequency changes most significantly for Garfield Park, West Garfield Park, West Englewood and Englewood community areas. West Englewood and Englewood have high Black population ratio and relatively low median household income. These two cites have very low toxic releases and no facility is located near these communities. However, they have a significantly higher frequency of all types of crime than other community areas. Since pollution level is low in these neighborhoods, socio-economic variables play a greater role in explaining crime occurrence.
Garfield Park and West Garfield Park have a high Black population ratio and low median household income. These areas also have moderate to high levels of toxic releases. The frequencies of assault, battery, and burglary and robbery significantly increase when the location of crimes is changed from indoor to outdoor. Therefore, toxic pollution emissions may have some influences over criminal activities --- when people are exposed to polluting environment, they become more aggressive. However, outdoor crime frequency is not increased in high toxic releasing communities such as New City, Near West Side, and Loop. Consequently, the causal linkage between pollution and criminal activity is not strongly supported in our analyses.
The limitations of our study are there are various factors influencing individuals' behaviors both psychologically and physically. There are hidden-variables that could have impacts on the spatial distribution of criminal activities. Furthermore, air pollution is difficult to measure and investigate because there are factors like wind, precipitation, and solar radiation that might influence the direction of the flow and the distribution of emitted particles. Therefore, further analyses need to be conducted such as incorporating weather data into the study to measure pollution precisely.