A Geographic Method to Environmental Justice

Glimpsed by the windshield as you head south out of San Francisco, the Bayshore Freeway is only a 50-mile stretch of US Route 101 that connects the town with San Jose. What you don’t see is a mile-wide hall of higher-than-average air pollution to the west.

By the point you attain Redwood Metropolis and enter Silicon Valley, the air pollution hall has widened and switched sides. There, the heavy air pollution zone lies nearly solely east of the freeway, which seems as a dividing line between two worlds, as stable and impermeable as a political border.

CalEnviroScreen, an internet map constructed by the Workplace of Environmental Well being Hazard Evaluation (OEHHA), a part of the California Environmental Safety Company (CalEPA), gives this view. Combining knowledge associated to air pollution and other people, the map exhibits California from an environmental justice perspective.

Utilizing trendy geographic data system (GIS) expertise, CalEnviroScreen ranks and colour codes California’s greater than 8,000 census tracts to mirror vulnerability to air pollution. The components behind CalEnviroScreen considers the presence of varied kinds of air pollution, the prevalence of well being issues that may be worsened by air pollution, and inhabitants knowledge.

CalEnviroScreen is a screening software used to assist establish communities disproportionately burdened by a number of sources of air pollution and with inhabitants traits that make them extra delicate to air pollution. (Click on on the picture to go to the interactive CalEnviroScreen 4.0 map)

Along with exhibiting this general rating, CalEnviroScreen is designed with instruments for constructing maps that isolate any of 21 datasets. One might uncover, for example, that the town of East Palo Alto has considerably extra waste remedy websites, groundwater contamination, and lead publicity—and better charges of bronchial asthma, coronary heart illness, and low start weight—than Palo Alto and Menlo Park, its neighbors throughout the freeway. Reconfiguring the map additional reveals that East Palo Alto residents additionally expertise extra poverty, unemployment, and prohibitively excessive housing burden.

A Holistic Method

One of many environmental justice motion’s key tenets is that air pollution—and its results—are erratically distributed. The presence of air pollution, moreover, does greater than contribute to a neighborhood’s in poor health well being; it additionally perpetuates it, exacerbating social circumstances that aren’t instantly brought on by air pollution.

Translating this holistic perspective into the language of maps was a serious focus throughout CalEnviroScreen planning classes within the mid-2000s. “A number of related initiatives had checked out particular person components, however a driving power behind CalEnviroScreen was determining the way to mix them,” mentioned Walker Wieland, an OEHHA analysis scientist and GIS knowledgeable.

In communities with a heavy air pollution burden, Wieland defined, an already embattled inhabitants experiences it in a approach that makes it even heavier, creating an oppressive suggestions loop.

“Residents typically reside in areas with socioeconomic traits, resembling excessive poverty and low instructional attainment, that may make them extra susceptible to the consequences of that air pollution,” he mentioned. “It’s the air they’re respiratory, the water they’re ingesting.”

Greater than a Map

The map itself is simply essentially the most seen manifestation of CalEnviroScreen, which CalEPA calls a “screening methodology . . . to assist establish California communities which are disproportionately burdened by a number of sources of air pollution.” In different phrases, it’s each a map and a approach to consider the facility of maps, on this case facilitating a geographic method to appreciate the objectives of environmental justice.

CalEPA encourages neighborhood teams to make use of the software to know how their neighborhoods are impacted by air pollution. The map’s format emphasizes particular classes of inequities—by color-coding based mostly on percentile—slightly than a uncooked air pollution rating.

A person can shortly uncover, for example, {that a} census tract’s air pollution burden is greater than the air pollution burden in 90 % of all different tracts. “The ability of CalEnviroScreen is that you should utilize it as a relative software, to point out that this neighborhood is extra burdened than that one, and right here’s the info to show it,” Wieland mentioned.

The map offers deep context that tells a narrative—the extra one investigates, the extra advanced narratives emerge. Zoom out a bit in order that your imagined drive on the Bayshore Freeway begins on the base of the San Francisco-Oakland Bay Bridge. CalEnviroScreen reveals that close by Market Avenue marks a pollution-burden divide as stark as what you’ll discover if you attain Silicon Valley. Zoom out additional and also you’ll discover a high-burden air pollution ring extends round a lot of the bay.

An Even Sharper Focus

CalEPA considers CalEnviroScreen a perpetual work in progress. For example, earlier variations didn’t permit customers to generate maps of particular person indicators, a functionality typically requested by neighborhood teams.

“Now you’ll be able to establish areas that will rating excessive in a single or two indicators—like air air pollution or proximity to [chemical] cleanup websites—however don’t register excessive on the cumulative map,” Wieland mentioned.

This alteration makes the tales advised by CalEnviroScreen much more advanced. East Palo Alto’s general burden is comparatively giant, however the metropolis is usually unaffected by pesticides. Nevertheless, Menlo Park, Palo Alto, and the encircling environs—together with Stanford College—have a number of the Bay Space’s highest pesticide percentiles.

Wieland mentioned OEHHA additionally produces a report evaluating CalEnviroScreen alongside racial and ethnic knowledge, and continues to guage new indicators and methodologies. The company additionally hopes to enhance characterization of indicators in tribal and rural communities.

“There’s clearly far more than 21 datasets that would go into CalEnviroScreen,” Wieland mentioned. “However our course of is rigorous and scientific. We wish to make a software that’s sturdy, defensible, and highly effective for the big selection of those that use it.”


Learn the way GIS can be utilized to detect air pollution patterns. The Air High quality Conscious app gives a map of air high quality throughout the US from data shared by US Environmental Safety Company.

In regards to the writer

Steve Homosexual

Steve Homosexual helps state governments use location intelligence to handle challenges as assorted as emergency administration, land use planning, utility infrastructure optimization, and habitat conservation. As an account supervisor at Esri, Steve works carefully with state executives, division leaders, and finish customers to tailor GIS expertise to the wants of the communities they serve. He has labored within the GIS business for over 20 years, and obtained a geography diploma from College of Kansas. He enjoys climbing, tenting, and educating younger individuals on the significance of defending the outside.

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