Power plants may emit higher amounts of pollution during lapses in federal monitoring and enforcement, such as during a government shutdown, according to a new study led by researchers at Penn State.
The study, published in the Journal of the Association of Environmental and Resource Economists, details the short-term effects of enforcement of federal environmental laws and regulations on power plant air emissions.
Using data from the 2018-19 federal government shutdown, which lasted 35 days, as a natural experiment, the researchers found that coal-fired power plants increased daily emissions of particulate matter - tiny solid particles and liquid droplets suspended in the air - during the furlough of federal employees.
This increase may be caused by the temporary reduction of efforts from the power plants to limit pollution, according to Ruohao Zhang, assistant professor of agricultural economics in the College of Agricultural Sciences and lead author on the paper.
At the same time, Zhang explained, the researchers found no detectable increase in daily emissions of sulfur dioxide or nitrogen oxides. This was likely because the U.S. Environmental Protection Agency's Clean Air Markets Division has monitored and enforced limitations on these pollutants continuously since 1995, so they were not affected by the government shutdown.
Zhang said the findings are important because even small increases of pollution can affect human health. They also suggest that inspections and enforcement efforts are crucial for mitigating pollution both in the long run and on a daily basis.
"Interruptions in inspections and enforcement have the potential to trigger immediate environmental and health consequences," he said. "Moving forward, policies should ensure stable inspection capacity, minimize enforcement gaps and expand continuous emission monitoring."
The EPA plays a key role in ensuring compliance with federal environmental laws and regulations, the researchers said, with monitoring and enforcement activities as its primary responsibility.
However, the EPA's resources for these activities have declined over time, with shrinking budgets and reduced enforcement staff. Consequently, the number of inspections and time for enforcement have also decreased over the years.
"This reduction in monitoring and enforcement raises concerns about the weakening of regulatory stringency and environmental compliance," Zhang said. "We wanted to investigate the effect of reduced monitoring and enforcement efforts on firms' pollution and compliance with environmental regulations."
However, the researchers said studying the impact of reduced monitoring and enforcement can be challenging. Fewer inspections may simply indicate strong compliance, for example. Additionally, it can be difficult to pinpoint the effectiveness of monitoring and enforcement in achieving or maintaining regulatory compliance.
For the study, the researchers compiled data from several sources. A list of coal-fired power plants came from the U.S. Energy Information Administration, and data on emissions and operations - including daily power plant emissions of sulfur dioxide, nitrogen oxides and carbon dioxide, as well as daily heat input, electricity generation and steam production - came from the EPA's Air Market Program.
They then compared power plants' daily operations and emission behaviors before and after the EPA furlough to detect any short-term changes resulting from the temporary absence of regulatory inspections and enforcement.
The researchers found that the aerosol concentration of particulate matter surrounding the power plants increased significantly during the EPA's furlough. The average aerosol optical depth - a measurement of how many aerosols are in the atmosphere - for the U.S. is 0.1 to 0.15. During the furlough, aerosol concentrations within a three-kilometer radius of the power plants were higher by 0.018-0.022, on average.
"Studies have shown that even short-lived increases in particulate matter have the potential to worsen public health outcomes," Zhang said. "Evidence links small increases of fine particulate matter with diameters of 2.5 micrometers or less to higher mortality risks. Stable enforcement and continuous monitoring are useful tools for ensuring compliance, reducing emissions and protecting health."
Huan Li, North Carolina A&T State University, and Neha Khanna, Binghamton University, also co-authored this paper.
