This story was first published by Undark and is reproduced here as part of the Climate Desk collaboration.
Paula Brooks stands in front of her two-bedroom house on Camp Street in Indianapolis and glances south, she sees brightly painted historic homes and towering oaks. She can see traffic when she turns her head north. Traffic roars by all day. At rush hour, traffic clogs as commuters squeeze onto Interstate 65.
“The majority of those heavy vehicles are using diesel, so when it gets congested, you know cars idling, then it really hits you, the fumes,” says Brooks, who grew up in this historic African American neighborhood known as Ransom Place.
Diesel engines emit microscopic particles of pollution called fine particle matter. They are roughly 2.5 microns in size and 30 times smaller than a human hair’s width. This is what scientists call pollution. PM2.5Researchers have linked the particles to the particles that can lodge deep within the lungs and get into the bloodstream. Cardiovascular disease, Diabetes, Autism, Asthma, Chronic obstructive Pulmonary Disease, and even Alzheimer’s disease.
In theory, a network of Environmental Protection Agency monitors should help track this pollution in Brooks’ neighborhood—and similar places across the country. The most common EPA monitors consist of a metal box with a protruding device at the top to draw in air. The instruments inside control the airflow and deliver it to a filter system that captures pollutants. Under the Clean Air Act, state regulators are required to put these monitors around geographical regions—usually counties. The regulators then use the monitors’ data to show they are complying with the National Ambient Air Quality Standards, which Limitations how much of a certain pollutant is allowed in a cubic meter of air.
In practice, experts and advocates often say: This system Broken. Data Collect by researchers at the nonprofit Resources for the Future, along with studies from at least one academic group, suggests that actual levels of some air pollutants in Ransom Place and other US neighborhoods are higher than what the monitors indicate. They say that there are too few monitors to accurately measure local pollution levels.
Five PM2.5 monitors cover 400-square mile of Marion County, which is where Indianapolis is. They are not located in the city core, where traffic is at its worst. “Our stationary monitors are not well suited to pick up our worst emitters,” says Gabe Filippelli, a biogeochemist at Indiana University-Purdue University Indianapolis who studies air pollution.
Some researchers believe that state regulators might be motivated to keep monitors away polluting hotspots, as a reward for their limited supply. Gaming the regulatory system might not be limited to monitor placement. Some recent work suggests that regulators take advantage of intermittent monitoring, an EPA practice that allows regulators to turn on monitors just once every three or six days. Other Research shows how facilities may exploit a Clean Air Act provision to avoid penalization by claiming any excess emissions—above what their EPA permit allows—were unintended.
The result of all this overlooked pollution, the researchers say, is that people get hurt—mostly people of color. A 2021 Study in Science Advances shows racial-ethnic minoritiesIn the United States are disproportionately exposed to higher levels of PM2.5. The authors calculated pollution levels from vehicles, construction, industry, etc. and found that Black, Asian, or Hispanic people breath dirtier air than Whites.
This unequal exposure is due to racism, says Julian Marshall, study coauthor and a civil and environmental engineer at the University of Washington. He cites discriminatory housing and land-use policies from the past, including Mortgage redliningThis meant that Black Americans and people of color couldn’t get government-backed loans for their homes. Redlining neighborhoods was seen as a good place for industry and highways by city planners. However, residents were not able to resist such developments. These explicitly racist policies from decades ago still impact the people who breathe the dirtiest air today, says Marshall: “The past is still present.”
For many years, the EPA’s ground monitors were the only way to measure pollution. In 1999, NASA was established. Launched a rocket from California’s Vandenberg Air Force Base—and with it, a new system for gathering pollution data. A satellite that flies once per day over every inch of the planet was on board that rocket, which I took along. With another satellite launched in 2002, it gathers data on the concentration of pollution particles by comparing solar radiation at the top of Earth’s atmosphere with how much is reflected back from Earth’s surface—the more particles, the less radiation is reflected back.
Researchers have now been analyzing satellite data for two decades to get a more complete picture of Earth’s pollution, but they are still refining the statistical tools needed to interpret the data. Satellite measurements do not provide direct samplings of pollutants particles so researchers must use a statistical transformation process to at least One study showed can involve a lot of error. Meredith Fowlie, University of California, Berkeley professor, said that this means data should be viewed cautiously. In an email to Undark, she explained that the EPA monitors provide a direct measure of pollution; whereas, the satellite-based estimates are “informed guesses coming out of a very challenging prediction exercise.”
Still, Fowlie and others see value in looking at satellite pollution estimates to fill in the data gaps inherent among the nation’s ground monitoring network. Satellite estimates show, for example, that some monitors may not be detecting pollution. Researchers, including Alan Krupnick, a senior researcher at Resources for the Future and Corbett Grainger at the University of Wisconsin Madison, believe this to be strategic. Both have been comparing satellite data with ground monitor data and have found evidence that in some counties, including where Brooks lives, monitors may sit just outside pollution hotspots—perhaps because state regulators want to avoid costly investments necessary to bring down pollution levels.
Officials at the EPA disagree, pointing out that Guidelines on where their monitors should be sited. Barry Sneed spoke on behalf of the Indiana Department of Environmental Management. Undark via email that his agency follows those guidelines as best they can, adding that “there are limitations to locations that may otherwise be ideal such as vegetation, structures, or the lack of access to power.”
Regulators in other parts of the country may be taking advantage unintended loopholes in air monitoring, such as an EPA policy that allows regulators monitor pollution on an intermittent base. (EPA data shows that the annual cost for a monitor that’s turned on every day is $41,000, while it costs $21,000 to turn it off once every six weeks. The monitor will continuously measure pollution on different days of week using the one-in-six-day scheduling. The EPA states that the average number of pollutants captured should be representative.
According to recent research, however, Research by Eric Zou, an economist at the University of Oregon, local regulators may have found a way to skirt this rule. Zou said that local regulators are charged with forecasting local pollution levels so they can predict when air quality could be dangerous. They also know when the intermittent monitors will be activated (the EPA publishes a schedule). public schedule). And, critics say, local regulators should know that if they issue a pollution advisory—a warning to residents to stay indoors and drive less—they may be able to quickly lower pollution.
Zou compared daily NASA satellite PM2.5 data with one-in-six days measurements from ground monitors located in hundreds of countries. He found that pollution levels decreased on the day that the monitors were turned ON, and then rose again when they were turned OFF. He also found that local regulators were 10 percent more likely to issue an advisory, which have names like “Spare the Air,” on the days the monitors were turned on. “If you look at when these warnings are issued, look at the timing,” Zou says. “You can see a pile up of these issuances exactly on the days when the federal monitors are monitoring.”