By measuring the concentration of four major air pollutants — nitric oxide, nitrogen dioxide, black carbon and ultrafine particles — across a sample of 13 neighborhoods in the Bay Area, the researchers, including one from UC Berkeley, sought to understand differences in air pollution not only between neighborhoods, but also between blocks within the same neighborhood. The measurements were taken over a period of 32 months starting in May 2015 using sophisticated air monitors mounted on Google cars.
What they found was an overall pattern of racial and ethnic disparities in exposure to air pollution, with higher concentrations of pollutants found in predominantly Black and Latino communities. “We don’t all breathe the same air in the Bay Area or anywhere,” said Joshua Apte, a UC Berkeley air quality scientist involved in the study.
Among the neighborhoods studied, Downtown Oakland and West Oakland had some of the worst quality air, with high levels of all four pollutants tracked.
The study notes that many of the neighborhoods included in the study that show the highest pollution exposures were the same communities that endured racially discriminatory housing policies, such as redlining, during the 20th century. West Oakland, which Apte says is a “hotbed of environmental justice activism,” is an example. The Hunters Point and Bayview neighborhoods in San Francisco, which have historically faced numerous types of pollution exposures, were not included in the study.
Scientists also observed wide differences in air pollution levels within the same neighborhoods, Apte said. “So what block you live in in your neighborhood can have a pretty profound impact on your exposure, especially if you live in a more urban neighborhood where things are really quite variable.”
The data collection for the study was carried out by Aclima, a San Francisco-based public benefit corporation. Aclima’s technology-enabled sensors, which are more sophisticated and accurate than low-cost sensors like those from PurpleAir, were placed on Google Street View cars to capture and store scientific measurements on the go. The mobility of the sensors allowed pollution readings to be taken in many more places than are usually captured by government monitors.
The fleet of Google Street View cars drove more than 93 square kilometers repeatedly over the course of 32 months, collecting air pollution data every second, which scientists then combined with demographic data from the U.S. Census Bureau for their analysis. The analysis revealed systematically higher concentrations for Black and Hispanic/Latino people across geographies. The researchers also found that communities that suffer from environmental justice issues tend to be exposed to a lot of different types of air pollution sources, not just one.
The chart below shows the share of each race and ethnic groups living in communities with different levels of exposure to ultrafine particles, or UFP, which comes a variety of kinds of combustion, cooking, and regional air pollution events, like wildfires.
“On average, the White population is exposed to lower NO, NO2, and UFP than other groups, with a median exposure 16 to 27% below the total-population median, while medians for the Black and Hispanic/Latino populations are higher by 8 to 30% depending on pollutant,” the study claims.
The patterns for the Asian community were peculiar, Apte said. Asians were represented in both extremes — in the least polluted areas as well as the most polluted. "What that speaks to is that ‘Asian’ is just like (a) gross oversimplification of its really complex demographic and lived experiences,” he said.
The researchers hope data from this study, and others like it, will help people understand the finer details of air pollution, which will better equip communities trying to address the issue. “The solutions to problems of environmental justice really involve (people) rolling up their sleeves and thinking really holistically about all the things that disparately burden their community,” Apte said.
Dr. Melissa Lunden, chief scientist of Aclima, said her company is expanding this study to understand air pollution at a larger scale in the Bay Area by deploying more cars equipped with sensors across more neighborhoods in the region. “We really hope that we can support that kind of work in any region that really needs this sort of help,” she said.
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