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One Step Forward, Two Steps Back: The Recent Loosening of the Clean Air Act

By Angelica Li*

In 1963, Congress passed the first piece of air pollution control legislation, titled the Clean Air Act (CAA) of 1963.[i] Written with a few important goals in mind, this piece of legislation has gone through multiple changes and improvements since its initial passage[ii]. Its most essential goal was the improvement of the air quality of the United States in order to promote health and welfare among the nation’s people. [iii] In order to negate the possibility that air polluters would attempt to maximize pollution emissions into the atmosphere upon achieving the goal set for them by congressional mandates, a provision was added in 1995 to prevent “backsliding.”[iv] This provision has been called the ‘once in always in” (OIAI) provision. This provision mandates that the more dangerous major pollution sources, such as power plants, would always be subjected to major source control standards, even if the source was able to heavily reduce its potential for emitting hazardous air pollutants.[v] This would subject the major pollution sources to more stringent control restrictions than the area sources that historically emitted pollutants at lower levels.[vi] Area sources are smaller sources of air pollution, emitting less than 10 tons of any hazardous air pollutant per year, or less than 25 tons of combined hazardous air pollutants per year. [vii]These more stringent control restrictions, termed “Maximum Available Control Technology” (MACT), are based on the technology used for the source that has best controlled its air pollution emissions.[viii]

In early 2018, President Trump and the EPA set into motion a plan to withdraw the OIAI provision from the CAA. [ix] Under the newly edited version of the CAA, major sources could be rebranded as area sources once the major sources reduced pollutant levels below a specified threshold. [x] The main claim was that this decision followed logically from a “plain language” reading of the Clean Air Act § 112,[xi] which defines the two main sources of pollutants and sets the standards of controlling the sources’ emission levels.[xii] On a closer analysis of this reasoning however, this conclusion seems to be anything but logical.

The notion that a “plain language” reading of the CAA justifies this modification is a weak argument at best. Indeed, when one looks at the consequences of using such a method of legislative interpretation, it becomes clear that it should instead be avoided at all costs. Immediately following the removal of the OIAI policy, many voiced concerns that the change would result in “backsliding” of progress already made under the CAA.[xiii] There is good reason for this concern, even with the EPA’s assurances that this change would improve compliance with the CAA instead of increasing the amount of toxic pollutants released.[xiv] Perhaps the original OIAI arguably lowered the incentive to pursue a further decrease in pollution through methods such as innovative new technology.[xv] However, more likely the removal of the OIAI has actually decreased the incentive for polluters to minimize emissions overall. Under the new CAA, major pollution sources could decrease emissions below the major source threshold, and hover around that threshold while still being subject only to area source controls.[xvi] Similarly, current area sources could essentially maximize their pollution emissions by increasing the emissions until it is just below the major source threshold, and at the same time still be in compliance with the law. Instead of “continuing to ensure stringent and effective controls on hazardous air pollutants,”[xvii] a net increase in pollution is more likely to occur without OIAI in place. After all, it is unlikely that the MACT standards under the OIAI policy gave an incentive to polluters to hover around the threshold between the two types of sources.

A net increase in air pollution and a resulting decrease in air quality is not only contradictory to the legislative intent of the CAA, but it also means that there will be major negative impacts on human health and the environment. Studies have shown that air pollutants are associated with a wide range of illnesses in humans.[xviii] Mercury pollution is associated with negative effects on a developing baby’s neurological development. [xix]It furthermore damages human skin and eyes and has toxic effects on human nervous and digestive systems. [xx] Exposure to arsenic has also been associated with skin lesions and different types of cancers.[xxi] Documented environmental effects of air pollution include eutrophication of water bodies, as well as birth defects and reproductive failure in animal species.[xxii] The eutrophication of water bodies would lead to a loss of animal diversity, and air pollutants entering the water will enter the fish species that humans catch for food.[xxiii] In the end, the environmental effects are likely to harm humans.

Whether or not a “plain language” reading of Section 112 of the CAA calls for the move that the EPA has taken today, it is clear that this path of statutory interpretation is not the one that should be chosen. It is unreasonable to think that a law was passed with the intent to be interpreted in a way that results in a complete contradiction of its stated goals. While the OIAI policy is not without its faults, the dangerous range of effects that its removal could and likely will have are enough to justify keeping the policy where it originally was.

*Angelica Li is a Junior Editor on MJEAL. She can be reached at

The views and opinions expressed in this blog are those of the authors only and do not reflect the official policy or position of the Michigan Journal of Environmental and Administrative Law or the University of Michigan.

[i] Evolution of the Clean Air Act, Envtl. Protection Agency (Jan. 3, 2017),

[ii] Evolution of the Clean Air Act, Envtl. Protection Agency (Jan. 3, 2017),

[iii] Clean Air Act of 1970 § 101(b), 42 U.S.C § 7401 (2015).

[iv] Press Release, Envtl. Protection Agency, Reducing Regulatory Burdens: EPA Withdraws “Once in Always in” Policy for Major Sources Under Clean Air Act (Jan. 25, 2018),

[v]  Brian C.S. Freeman, Time to Toss It Out? The “Once in Always in” Policy for “Major Source” Hazardous Air Pollutant Standards, Envtl. Law Institute (July 2017),

[vi] Summary of the Clean Air Act, Envtl. Protection Agency (Aug. 24, 2017),

[vii] Section 112(a)-Definitions, Envtl. Protection Agency (Feb.23, 2016),

[viii] “Once in Always in” Guidance for Major Sources Under the Clean Air Act, Harv. Law Sch. Envtl.  Policy Initiative visited Feb. 18, 2018).

[ix] Eric Beech, U.S. EPA Reverses Policy on ‘Major Sources’ of Pollution, Reuters (Jan. 25, 2018, 9:37 P.M.),

[x] Umair Irfan, The Trump Administration is Lifting Key Controls on Toxic Air Pollution, Vox (Jan. 26, 2018, 4:40 P.M.),

[xi] Memorandum from William L. Wehrum, Assistant Administrator of the U.S. Envtl. Protection Agency Office of Air & Radiation to the Regional Air Division Directors (Jan. 25, 2018).

[xii] Clean Air Act of 1970 § 112, 42 U.S.C § 7401 (2015).

[xiii] Irfan, supra note 8.

[xiv] Jennifer A. Dlouhy, Lifting Pollution Curbs Won’t Unleash Toxins, U.S. Regulator Says, Bloomberg Politics (Jan. 29, 2018, 4:37 P.M.),

[xv] Envtl. Protection Agency, supra note 3.

[xvi] Dlouhy, supra note 12.

[xvii] Envtl. Protection Agency, supra note 3.

[xviii] Marilena Kampa and Elias Castanas, Human Health Effects of Air Pollution, 151 Env. Protection 362 (2008).

[xix]  Mercury and Health, World Health Org. (Mar. 2017),

[xx] Id.

[xxi] Jin-Yong Chung, et al, Environmental Source of Arsenic Exposure, 47(5) J. of Preventative Med. & Pub. Health 256 (2014).

[xxii] Health and Environmental Effects of Air Pollution, Mass. Dep’t of Envtl. Protection, (last visited Feb. 18, 2018).

[xxiii] Id.

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