Air Quality Analysis Narrative

Subtitle: Traffic Burden, PM2.5 and Toxic Release Impact on California Counties

Data source: CalEnviroScreen 4.0

Background: The CalEnviroScreen data is data collected from California counties in order to help identify census tracts and communities most affected by environmental hazards. This newest version of the data (4.0) was released in 2021. Census tracts receive a score based on pollution burden and population vulnerability (higher scores show greater impact). It includes demographic, health and environmental data that can be analyzed to help prioritize resources and targeted interventions. This dashboard has visualizations focus on the distribution of traffic burden, PM 2.5 Levels and Toxic Releases in California. It can be used to direct funding or inform policies that can help mitigate the impact on the health of the residents of the populations most affected by these factors and the resultant air pollution.

Results: In Figure 1, the traffic burden map shows a higher traffic burden percentile (greatest traffic levels and vehicle emissions) in the counties of Los Angeles, Orange, Santa Clara and Marin. The general trend shows the largest counties to have the highest traffic burden, with the exception of Marin being a small county with high traffic burden.

Table 1 shows the PM 2.5 percentile levels are highest in the Central Valley counties of Tulare, Fresno, Kings, Kern and Merced, all ranking above Los Angeles even with its large size. The counties with the lowest PM 2.5 percentile levels are typically those with the least number of census tracts, with Monterey ranking lowest.

Figure 2 and Table 2 show toxic release values are low throughout the state, with the exception of high values in Central Valley and Los Angeles counties. The most affected counties by toxic release are Madera, Los Angeles and Orange.

Traffic Burden and PM2.5 Levels

Column 1

Figure 1. Traffic Burden by California County (click to see percentile)

Column 2

Table 1. PM2.5 Levels Ranked by California County

Table 1. PM2.5 Percentile by California County

Toxic Release Exposure

Column 1

Figure 2. Toxic Release Exposure Heat Map

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Coordinate Reference System:
  User input: NAD83 
  wkt:
GEOGCRS["NAD83",
    DATUM["North American Datum 1983",
        ELLIPSOID["GRS 1980",6378137,298.257222101,
            LENGTHUNIT["metre",1]]],
    PRIMEM["Greenwich",0,
        ANGLEUNIT["degree",0.0174532925199433]],
    CS[ellipsoidal,2],
        AXIS["latitude",north,
            ORDER[1],
            ANGLEUNIT["degree",0.0174532925199433]],
        AXIS["longitude",east,
            ORDER[2],
            ANGLEUNIT["degree",0.0174532925199433]],
    ID["EPSG",4269]]
Coordinate Reference System:
  User input: EPSG:4326 
  wkt:
GEOGCRS["WGS 84",
    ENSEMBLE["World Geodetic System 1984 ensemble",
        MEMBER["World Geodetic System 1984 (Transit)"],
        MEMBER["World Geodetic System 1984 (G730)"],
        MEMBER["World Geodetic System 1984 (G873)"],
        MEMBER["World Geodetic System 1984 (G1150)"],
        MEMBER["World Geodetic System 1984 (G1674)"],
        MEMBER["World Geodetic System 1984 (G1762)"],
        MEMBER["World Geodetic System 1984 (G2139)"],
        MEMBER["World Geodetic System 1984 (G2296)"],
        ELLIPSOID["WGS 84",6378137,298.257223563,
            LENGTHUNIT["metre",1]],
        ENSEMBLEACCURACY[2.0]],
    PRIMEM["Greenwich",0,
        ANGLEUNIT["degree",0.0174532925199433]],
    CS[ellipsoidal,2],
        AXIS["geodetic latitude (Lat)",north,
            ORDER[1],
            ANGLEUNIT["degree",0.0174532925199433]],
        AXIS["geodetic longitude (Lon)",east,
            ORDER[2],
            ANGLEUNIT["degree",0.0174532925199433]],
    USAGE[
        SCOPE["Horizontal component of 3D system."],
        AREA["World."],
        BBOX[-90,-180,90,180]],
    ID["EPSG",4326]]

Column 2

Table 2. Toxic Release Exposure by California County