The Impact of the 2018–2019 Government Shutdown on Air Pollution
When the U.S. government shut down in late 2018, it furloughed nearly 600 Environmental Protection Agency (EPA) pollution inspectors for more than a month. These workers were responsible for monitoring and inspecting industrial sites for pollution, including enforcing environmental-protection laws like the Clean Air Act. During this period, the EPA was unable to carry out its usual duties, which led to a noticeable increase in pollution levels from coal-fired power plants.
How Coal Plants Responded to the Lapse in Enforcement
My colleagues and I analyzed six years' worth of air quality data, emissions measurements, power production data, and weather reports from over 200 coal-fired power plants across the country. We found that the operators of these plants appeared to take advantage of the lack of oversight during the shutdown.
As soon as the shutdown began, coal-fired power plants started producing about 15% to 20% more particle pollution. And when the government reopened and inspections resumed, pollution levels dropped back to their previous levels.
The Dangers of Particulate Matter
The longest federal government shutdown in U.S. history at that time began on December 22, 2018, and lasted until January 25, 2019. During this time, about 95% of EPA employees were furloughed, including nearly all of the agency's pollution inspectors. These inspectors are responsible for ensuring that industrial sites, such as coal-fired power plants, follow rules meant to limit air pollution.
One of the key pollutants regulated by these rules is particulate matter, also known as PM2.5 and PM10. These microscopic particles are smaller than the width of a human hair. When inhaled, they can travel deep into the lungs and even enter the bloodstream. Short-term exposure to particulate matter increases the risk of asthma, heart disease, and premature death.
Analyzing the Data: What Happened During the Shutdown?
To determine whether coal-fired power plants continued to obey the rules during the shutdown, we examined data on emissions from over 200 coal-fired power plants. We used satellite data from NASA, which provides a reliable indicator of particulate pollution in the atmosphere. We also looked at chemical emissions recorded directly from smokestacks and sent to the EPA.
We compared each plant’s daily emissions before, during, and after the 2018–2019 shutdown with emissions on the same calendar days in the five previous years. Our findings showed that particulate emissions within 1.8 miles (3 kilometers) around the coal-fired power plants increased during the shutdown, according to the NASA data.
On average, particulate matter during the shutdown was 15% to 20% higher than it had been during the same period in the preceding five years. Once the EPA inspectors returned to work, the plants’ average particulate pollution dropped back to pre-shutdown levels.
Why Did Other Pollutants Not Increase?
We also found that two other common air pollutants from coal-fired power plants—sulfur dioxide and nitrogen oxides—did not increase during the furlough period. Unlike particulate matter, these gases are continuously monitored by sensors inside coal plants' smokestacks, even when the federal government is not operating. Particulate emissions, however, are not continuously monitored; enforcement relies on manual sample collection and on-site inspections, both of which halted during the shutdown.
Considering Alternative Explanations
To confirm that the increase in particulate pollution was due to the lack of inspections and not other factors like weather fluctuations, we tested various alternative explanations. For example, weather records showed that wind, humidity, and temperature at and around the coal plants during the shutdown were within the same ranges as in the previous five years. This ruled out weather conditions as a cause.
Electricity demand—how much power the plants were generating—was also typical and did not increase significantly during the shutdown. This meant that the coal plants weren’t polluting more just because they were producing more electricity. Additionally, the analysis showed that the plants didn’t switch to less efficient boilers that would have produced more particulates.
Our data also included carbon dioxide emissions, which gave us insight into what the coal plants were burning. Similar weather conditions and electricity generation levels meant that different types of coal emit varying amounts of carbon dioxide. However, we did not find any significant changes in carbon dioxide emissions, indicating that the increase in particulate matter was not due to changing the type of coal being burned.
Could Coal Plants Quickly Adjust Their Emissions?
All of our tests confirmed that the spike in particulate matter pollution was unique to the 2018–2019 EPA furlough. Our final question was whether it was possible for coal-fired power plants to quickly increase—and then decrease—the amount of particulate matter they emit. The answer is yes.
Power plants use electrostatic precipitators to control particulate emissions. These devices use static electricity to collect particles from smoke and exhaust before they exit the smokestack. While they require electricity to operate, turning them off or reducing their operation can save money. During the shutdown, when oversight disappeared, plants could reduce their use of these devices with less risk of being caught and fined.
The Broader Implications
Our findings highlight the importance of strong and continuous enforcement of environmental regulations. Before the 2018 shutdown, EPA enforcement staff had declined by more than 20% between 2007 and 2018, and the number of inspections dropped by one-third. Since the new administration took office in January 2025, EPA staffing has been reduced significantly.
Without strong and continuous monitoring and enforcement, environmental laws risk becoming hollow promises. This study underscores the need for consistent oversight to ensure that pollution controls are actually working and that public health is protected.
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