Potential Regulation of Ammonia under the Clean Air Act

NCBA Staff Contact: 

Tamara Thies, Chief Environmental Counsel
202-347-0228

tthies@beef.org

Every five years, the EPA is required to review scientific studies associated with “criteria pollutants” regulated under the National Ambient Air Quality Standards (NAAQS) of the Clean Air Act to determine if the pollutant is regulated appropriately.  One of the criteria pollutants is particulate matter (PM).  The NAAQS is a health-based standard.  In other words, Congress determined that in order to regulate a pollutant under the NAAQS, scientific studies must show that the pollutant causes adverse health effects.  Conversely, if scientific studies do not show that a pollutant causes adverse health effects, it is not supposed to be regulated under the NAAQS. 

Prior to 1997, the EPA regulated PM with a standard of 150µg/m³ which applied to all PM in the size range of ten microns or smaller (PM10).  In 1997, the EPA decided to separate particles for regulatory purposes based on their composition and size since it was believed that these factors make a difference as far as health effects are concerned.  “Fine” PM (PM2.5) formed primarily by combustion or chemical reaction of gases falls in the size range of 2.5 microns or smaller.  “Coarse” PM (PM10) formed by mechanical processes consisting of minerals, crustal material and organic debris, i.e. dust, falls in the size range of 10 microns and smaller.  In 1997, the NAAQS for PM2.5 was 65µg/m³, the NAAQS for PM10 was retained at 150µg/m³.  In 2006, the EPA tightened the PM2.5 standard to 35µg/m³ and retained the PM10 standard of 150µg/m³.

After the EPA publishes its standards for regulating PM, it issues an “Implementation Rule” which outlines requirements states must meet when developing plans to control and reduce fine PM to ensure attainment status.  On April 25, 2007, the EPA published the “Clean Air Fine Particle Implementation Rule” for regulation of the 1997 fine PM (PM2.5) standard – that’s right, it took the EPA 10 years to issue this rule.

Scientific studies show that excess levels of fine PM cause serious adverse health effects in humans.  Unfortunately, ammonia is a well-known precursor to the formation of fine PM (as are SO2, NOx and VOCs).  These precursors undergo reactions in the atmosphere to form fine PM.  EPA is authorized to regulate precursors under the Clean Air Act.  But the EPA stated in the implementation rule that it does not believe it must regulate all precursors the same when there is a basis to distinguish between them.

Ammonia is emitted by natural and manmade sources.  But their inventories are considered to be among the most uncertain of any PM precursor.  In addition, ammonia serves an important role in neutralizing acid in clouds, precipitation, and particles.  In particular, it neutralizes sulfuric and nitric acid, the two key contributors to acid rain.  It also causes problems, however, like eutrophication of water, acidification of soil, and fine PM formation.  In addition, control techniques and tools to quantify impacts of reducing ammonia emissions are being studied.  Clearly, issues related to ammonia emissions are complex.

In the final fine PM implementation rule, EPA decided that ammonia would be presumed NOT to be a PM 2.5 attainment plan precursor and that states would not be required to address ammonia in SIPs or evaluate sources of ammonia emissions for reduction measures.  The rule states that this presumption can be reversed if a technical demonstration by the state or EPA shows that ammonia emissions significantly contribute to PM2.5 concentrations in a nonattainment area on a case-by-case basis.  When making this demonstration, the state “should also consider the potential for atmospheric and particle acidity to increase with ammonia reductions.”

On June 26, 2007, Earthjustice, an environmental legal organization representing the American Lung Association, Natural Resources Defense Council, the Sierra Club, and Medical Advocates for Healthy Air, appealed EPA’s decision regarding ammonia to the DC Circuit Court of Appeals.  In its press release regarding the appeal, Earthjustice stated the following:  “Fine particle pollution from power plants, industrial agriculture operations and other sources poses a significant health threat for some of the most vulnerable people in our community.  Children, adolescents, seniors, people with asthma and chronic lung diseases, people with chronic heart disease and diabetics are most at risk . . . One of the more egregious decisions is to allow states to avoid placing controls on sources such as mega dairy farms and other industrial agriculture sources that emit ammonia.  Ammonia reacts with other pollutants to form fine particles that are harmful to breathe.  EPA has nonetheless concluded that sates to not need to control or even evaluate the pollution associated with ammonia emissions.  This is a big giveaway to big agriculture, pure and simple.”

Given the significant impact this appeal could have on cattle operations, NCBA intervened in the appeal in support of EPA’s decision not to presume that ammonia is a PM2.5 attainment plan precursor.  No briefing schedule has been issued and no date for oral argument has been set.