A recent Government Accountability Office (GAO) report prepared at the request of Senator Sheldon Whitehouse (D-RI) claims that tall smokestacks are one of several factors that contribute to the interstate transportation of sulfur dioxides and nitrogen oxides. According to the report, tall smokestacks, which are 500 feet or higher and used primarily at coal-fired power plants, release air pollutants high into the atmosphere to help limit the impact of the emissions on local air quality. The report asserts, however, that they can also increase the distance pollutants travel in the atmosphere and harm air quality and the environment in downwind communities.

GAO was specifically asked to report on (i) the number and location of tall stacks 500 feet or higher at coal-fired power plants and when they began operating, (ii) what is known about their contribution to the interstate transport of air pollution and the pollution controls installed at the plants, and (iii) the number of stacks that were built above general engineering practice (GEP) height since 1988 and the reasons for doing so. Section 123 of the Clean Air Act does not limit stack height, but prohibits sources of emissions from using the dispersion effects of stack heights in excess of a stack’s GEP height to meet emissions standards.

As of December 31, 2010, the report found that 284 tall smokestacks—half of which were 30 years old—were operating at 172 coal-fired power plants in 34 states, with approximately one-third of those in the Ohio River Valley. Of tall smokestacks built since 1988, 17 were built in excess of their GEP height. GAO made no recommendations in the report, which EPA and the Department of Energy will use to finalize regulations on interstate air pollution.