We can see factory farm pollution all the way from space

In communities living next to factory farms, residents have long voiced their concerns about environmental pollution. Now, research shows that not only can we see the air pollution generated by industrial swine facilities, but we can see that it’s disproportionately affecting communities of color — all the way from space. A new study published in Environmental Science & Technology used satellite data to measure ammonia — a common pollutant produced by factory farms from the massive amounts of animal manure — in North Carolina. Across the eastern part of the state, University of Virginia researchers saw that ammonia levels were elevated in areas where there were high concentrations of industrialized pig facilities. In their research, they found significant population disparities. From 2016 to 2021, ammonia levels were 49 percent higher for Indigenous communities, 35 percent higher for Hispanic and Latino communities, and 27 percent higher for Black communities, compared to non-Hispanic white communities. [Image: Ammonia columns (figure a), permitted animal and swine facilities (figure b), and population by race/ethnicity (figure c). https://platform.vox.com/wp-content/uploads/sites/2/2025/02/Screenshot-2025-02-04-at-4.24.33%E2%80%AFPM-1.png?quality=90&strip=all] Ammonia has a distinctly unpleasant smell and can irritate the respiratory tract and skin. So for the people who live near these facilities, these findings likely won’t come as a surprise — they can smell and feel it. In the 2022 documentary The Smell of Money, which follows a community’s fight against a factory farm in North Carolina, residents talked about the revolting odor they’re forced to smell daily and their experiences of difficulty breathing, nausea, and chronic conditions like asthma. But as obvious as this information may be to residents affected by factory farms, having data to back up their claims of air pollution and other nuisances is important, said Sally Pusede, lead author of the study and an associate professor at the University of Virginia’s Department of Environmental Sciences. What makes this study unique, she argued, is that it’s taking measurements of an air quality impact and proving that it’s unequally distributed to communities of color in Eastern North Carolina. The study also highlighted a gap in tools and regulations: The researchers used space-based technology to consistently measure ammonia, which isn’t regularly monitored by state or federal agencies. “There are very few measurements of air pollution associated with industrialized agriculture from the ground,” Pusede told Vox. Even if residents are experiencing the health effects of exposure to ammonia, little can be done if there’s no data or a system in place to show they’re being exposed. “Without data to show that and support that, those claims can be contested.” How to measure ammonia from space There are five criteria for air pollutants that the US Environmental Protection Agency (EPA) monitors, as mandated by the Clean Air Act: particulate matter, ozone, carbon monoxide, sulfur dioxide, and nitrogen dioxide. Enacted in 1963, the Clean Air Act aimed to mitigate the pollution from a growing amount of cars, power plants, and other industrial pollution sources. Notably, ammonia isn’t one of these regulated pollutants, nor are other agriculture-related pollutants like nitrogen oxide or hydrogen sulfide. In a 2018 settlement, North Carolina’s Department of Environmental Quality agreed to conduct an air monitoring study in Duplin County after local environmental justice groups filed a 2014 federal civil rights complaint claiming pollution emitting from nearby swine facilities was disproportionately in nonwhite, low-income communities. As part of the settlement, the state environmental department’s Division of Air Quality (DAQ) measured pollutants including ammonia, hydrogen sulfide, and PM2.5 (a deadly pollutant also known as fine particulate matter) over the course of a year. When the DAQ finished the study, it presented its findings: ammonia concentrations were not detectable aside from five occasions, and only one of those occasions approached North Carolina’s “acceptable ambient level.” So how could the state’s measurements find nearly no measurable concentrations of ammonia, despite residents’ longtime experience with strong odors and health conditions? Pusede says the results from her team’s study raise a lot of questions about how well the state’s study was done. “I think that there’s a conflict between an agency that has as its primary goal regulatory compliance, versus one that has as its primary goal protection,” said Pusede. She also noted that the instrument used by DAQ may not have been able to properly detect ammonia levels. For Pusede’s study, researchers measured ammonia levels with an Infrared Atmospheric Sounding Interferometer (IASI), which resides on satellites in orbit. “It’s a space-based instrument that takes advantage of the fact that certain gasses interact with very specific wavelengths of light,” said Pusede. “You can take that interaction and use it to produce a column concentration of specific pollutants.” IASI collects data spatially every day. That allowed the researchers to map ammonia levels across entire regions of North Carolina and across an extended period of time. Alongside the IASI, the researchers used data from the US Census Bureau to access race and ethnicity data in North Carolina, weather condition data to calculate mean wind speeds and air temperature, and the North Carolina Department of Environmental Quality’s database on permitted industrialized swine facilities. Researchers also found that weather conditions could exacerbate these inequalities. On hotter days, ammonia inequalities were higher by 31 percent for Black communities than for white communities. On days with calm winds, ammonia inequalities were higher by 64 percent in Indigenous communities — double the disparity from windy days. According to Pusede, ammonia can travel downwind, deposit onto the ground, and then as surfaces warm up, the pollutant can return back to the air in a process called ammonia bidirectional flux. This means that ammonia can degrade the air quality beyond the immediate vicinity of a swine facility, at an average of 5 kilometers (or a little over 3 miles) downwind of these facilities from April through August, the study says. But in all 50 states, “right to farm” laws have limited who can file complaints. In North Carolina, only people living a half-mile from the site of a claimed nuisance (such as awful odors) can take action. Heightened ammonia levels on hot days are also cause for concern when we’re facing a global warming crisis. More hot days means more opportunity for ammonia to spread and further intensify air pollution inequalities for Black, Hispanic, and Indigenous communities. But none of these results surprised Pusede. “What we found was consistent with what people were saying,” she said. “I think part of the question is, why do we have a black hole over eastern North Carolina in terms of ammonia?” said Chris Brown, director of research and education at North Carolina Environmental Justice Network. (This was one of the groups that filed the 2014 complaint). “It’s because our regulators have made it so that there can be this rapid expansion of an incredibly environmentally hazardous economic model,” they told Vox. The scope of this new UVA study helps show the scale of the issue, says Brown. The long-documented health consequence of factory farms Indeed, there’s a healthy amount of scientific evidence that shows the agricultural industry has adverse consequences on air quality in places like North Carolina, one of the nation’s top pork producers. One study found that there are 17,900 deaths annually because of reduced air quality from the industry’s activities — and that a large driver of these deaths came from ammonia emissions from animal waste and fertilizer application. “It can affect the quality of your health while you’re alive,” said Jason Hill, lead author of this study and a professor at the University of Minnesota’s Department of Bioproducts and Biosystems Engineering. “But it also can increase your likelihood of dying early as a result of those acute conditions of heart attacks, strokes, cancer, and so forth.” Hill’s research found that there are a number of different inventions that could be taken to reduce air quality deaths from food producers: reducing food waste, lowering emissions from equipment, and improving fertilizer application processes, as well as manure management. Together, his team estimated that this could reduce premature deaths associated with food production by 50 percent. Pusede says the findings from her team’s research could be used by the state for future decision-making, including incorporating the research’s measurements into the Department of Environmental Quality’s community mapping tool, which gives the public a map of the spatial relationship between demographics like race, factory farms, permits, and health data. Brown says the UVA study shows the need for air quality permits. “There needs to be a standard in which each facility has to manage and monitor their own air emissions, to be able to have some accountability there,” they said. It’s not just air pollution that people are worried about, either. Waterways are prone to becoming contaminated with pollutants from factory farm waste, risking the public’s health and the integrity of another one of our key natural resources. North Carolina is also a particularly hurricane-prone state, and when these disasters hit, factory farms flood and “all of their feces, urine, waste goes everywhere,” said Brown. Despite research and lived experience showing the health impacts of the agricultural industry and a range of solutions to alleviate these harms, little has been done to change this on a policy level — even for something as seemingly straightforward as regulating and monitoring these pollutants. “There are very strong interests in not knowing what those emissions are, and not having them tied to specific facilities,” said Hill. Having that knowledge, via mandated measurements and monitoring of pollutants, would then hopefully force the agricultural industry to take some accountability. But with the industry as powerful as it is, it’s unlikely that they’ll be required to take steps to protect the public anytime soon. “Even when we gain a tool for accountability, the power structures of agriculture within our state legislature is so tight that any tools that we have get taken away,” said Brown. For now, studies like Pusede’s back up communities’ claims of harms on their health and livelihood from these facilities — and fuels their fight to clean air and water.

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We can see factory farm pollution all the way from space