Over the years, growing evidence has revealed a stark injustice: in comparison with wealthy cities, poorer cities are disproportionately affected by smog and soot.
A knowledge-driven map of individual neighborhoods within the San Francisco Bay Area and the three other major metropolitan regions in California now shows intimately how exactly these differences actually exist.
“The poorest are at the highest risk,” said researcher Jason Su of UC Berkeley’s School of Public Health, whose work in this week's issue of the journal Science Advances.
The latest study provides a more detailed overview than previous research of the various experiences of various communities, from the busy transit corridors of the East Bay to quiet and affluent suburbs within the Peninsula Hills. It may help inform disease surveillance and provides state authorities the information they should goal interventions.
“Research like this underscores the fact that clean air is a matter of justice. That is why California Air Resources Board prioritizes equity and justice in climate and clean air investments to ensure no one is left behind as we work toward a clean air future in California,” said board spokesperson Amy MacPherson.
For example, the study found that nitrogen dioxide, or smog, is more prevalent in poorer areas of East and West Oakland, that are bordered by Interstate 80, 880, 580 and State Route 24. Pollution can be higher within the working-class neighborhoods of Richmond, San Leandro and East San Jose, that are also crossed by major traffic arteries.
In contrast, the air is way cleaner in greener, windswept and more affluent neighborhoods like Alameda, Redwood Shores, Millbrae and Berkeley Hills.
Particulate matter or soot pollution follows an analogous pattern. Levels are higher, for instance, in East San Rafael on the foot of the 580 Richmond San Rafael Bridge. Soot can be more common in Redwood City, between busy highways 82 and 101, and in Martinez, where Interstate 680 crosses the Benicia Bridge. Soot is less common within the neighborhoods of Corte Madera, Burlingame, Foster City, and the hills above Milpitas.
Some of probably the most polluted communities are victims of their geographic location: they’re positioned in depressions where dirty air collects. Some are positioned next to power plants, hazardous waste generators or other sorts of environmentally harmful infrastructure.
But the overwhelming majority of the population is affected by the Bay Area's nonstop traffic. Masses of cars, SUVs and trucks emit nitrogen dioxide, which might cause asthma and other respiratory problems. Vehicle engines also emit soot, which has been linked to lung cancer and cardiopulmonary disease.
“Traffic is the main source of air pollution,” said Su, whose team included experts from the UCSF School of Medicine, the UCLA Fielding School of Public Health, San Diego-based device maker ResMed Inc. and San Francisco-based Propeller Health, whose sensors and software perform data evaluation.
Previous research has attributed pollution in poorer neighborhoods to redlining, a practice that began within the Nineteen Thirties of denying home loans to people of certain ethnic groups in certain wealthy communities. Although this discriminatory practice officially led to 1968, it influenced today's zoning practices and the location of highways and industrial facilities.
Air quality in California has improved significantly for the reason that passage of the Clean Air Act within the Seventies, its amendments in 1990, and much more stringent state-specific measures.
But in some communities, progress is quicker than in others. The gap is closing, Su said, however it remains to be clearly visible.
The research was conducted using cutting-edge machine learning and large data processing methods to create high-resolution day by day air pollution maps for smog, soot and ozone across California between 2012 and 2019.
The maps were created using terabytes of information from 850 monitoring stations and diverse other data sources, including information on traffic, weather, land use and various geographic features across the state.
The datasets produced detailed pictures of air pollution in 4 metropolitan areas – San Francisco Bay Area, Los Angeles, Fresno and Sacramento – on the census tract level, based on race, ethnicity and socioeconomic drawback.
Most previous studies only examined large geographic regions at low resolutions of 5 to 16 kilometers. They were conducted over large time periods, perhaps only annually. And monitoring sites were sparsely distributed. Su said differences in exposure between privileged and disadvantaged communities couldn’t be distinguished.
This latest study compares pollution levels in geographic areas as small as one-tenth of a mile. It focuses on the concentrations of two specific pollutants – smog and soot – because they’re most strongly linked to health problems. It found that disadvantaged communities had higher concentrations than advantaged communities.
But there was also excellent news: Over the course of the seven-year study, radiation exposure decreased. And the decline in radiation exposure was best within the poorest communities.
The team also measured ozone, a secondary pollutant that is just not emitted directly by traffic or industry but is created by the sun heating pollutants. In general, wealthy or rural neighborhoods in California see increasing ozone concentrations because of what’s often called the “ozone paradox.” Ozone, which might irritate the respiratory system, is depleted by smog, which is more common in cities.
Recent efforts to scale back emissions within the transport sector, corresponding to tax breaks for plug-in electric vehicles and stricter emissions standards for heavy-duty engines, are a step in the correct direction, Su said.
However, he fears that some non-motor pollutants, corresponding to particles from tires, brakes and the road surface itself, will persist.
Across the state, disadvantaged neighborhoods within the greater Los Angeles area had the best concentrations of smog and soot.
In the greater Los Angeles area, 79% of disadvantaged communities were exposed to high levels of smog, in comparison with 6.2% within the Bay Area, 4.0% in Sacramento, and 0.1% in Fresno. Los Angeles also has the best levels of black carbon, with 70.4% of disadvantaged communities exposed, in comparison with 67% in Fresno, 62% in Sacramento, and 6.2% within the Bay Area.
“The Bay Area is the best – the lucky one,” Su said.
Originally published:
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