Ammonium nitrate products are manufactured and sold in various forms, depending upon their use. For example, ammonium nitrate fertilizer may be produced and sold in liquid form or as solid granules. According to The Fertilizer Institute, solid ammonium nitrate fertilizer is used heavily by farmers in Alabama, Missouri, Tennessee, and Texas primarily on pastureland, hay, fruit, and vegetable crops. In addition to its agricultural benefits, ammonium nitrate can be mixed with fuel oil or other additives and used by the mining and construction industries as an explosive for blasting. While ammonium nitrate can increase agricultural productivity, use of this chemical poses a safety and health risk because it can intensify a fire and, under certain circumstances, explode. Ammonium nitrate by itself does not burn, but it increases the risk of fire if it comes in contact with combustible materials. Ammonium nitrate that is stored in a confined space and reaches high temperatures can explode. An explosion is more likely to occur if ammonium nitrate is contaminated by certain materials, such as fuel oil, or if it is stored in large stacks. Because of ammonium nitrate’s potential to facilitate an explosion, facilities storing ammonium nitrate may pose a security threat in part because it can be used to make weapons. Ammonium nitrate fertilizer has been used by domestic and international terrorists to make explosive devices. For example, on April 19, 1995, ammonium nitrate fertilizer— mixed with fuel oil—was used by a domestic terrorist to blow up a federal building in Oklahoma City, Oklahoma. The explosion killed 168 people and injured hundreds more. Ammonium nitrate has been involved in several major chemical accidents over the past century, including explosions in the United States and Europe. In addition to killing at least 14 people and injuring more than 200 others, the explosion in West, Texas severely damaged or destroyed nearly 200 homes; an apartment complex; and three schools that were, at the time, unoccupied (see fig. 1). Prior to that incident, an explosion in 1994 involving ammonium nitrate at a factory in Port Neal, Iowa killed four workers and injured 18 people. In 1947, explosions aboard two ships holding thousands of tons of ammonium nitrate fertilizer killed more than 500 people, injured approximately 3,500, and devastated large areas of industrial and residential buildings in Texas City, Texas. In Europe, accidents involving ammonium nitrate have occurred in Germany, Belgium, and France. A 1921 accident in Germany and one in Belgium in 1942 caused hundreds of deaths after explosives were used to break up piles of hundreds of tons of ammonium nitrate, resulting in large scale detonations. In France, a ship carrying more than 3,000 tons of ammonium nitrate exploded in 1947, a few months after the Texas City disaster, after pressurized steam was injected into the storage area in an attempt to put out a fire. In 2001, an explosion at a fertilizer plant in Toulouse, France involving between 22 and132 tons of ammonium nitrate resulted in 30 deaths, thousands of injuries requiring hospitalization, and widespread property damage. Past accidents also indicate that smaller quantities of ammonium nitrate can cause substantial damage. For example, in 2003, an explosion of less than 6 tons of ammonium nitrate in a barn in rural France injured 23 people and caused significant property damage. OSHA and EPA play key roles in protecting the public from the effects of chemical accidents, with EPA focusing on the environment and public health and OSHA focusing on worker safety and health. Under the Occupational Safety and Health Act of 1970 (OSH Act), OSHA is the federal agency responsible for setting and enforcing regulations to protect workers from hazards in the workplace, including exposure to hazardous chemicals. In addition, the Clean Air Act Amendments of 1990 designated roles for both OSHA and EPA with respect to preventing chemical accidents and preparing for the consequences of chemical accidents. In response to requirements in this act, OSHA issued Process Safety Management (PSM) regulations in 1992 to protect workers engaged in processes that involve certain highly hazardous chemicals, and EPA issued Risk Management Program (RMP) regulations in 1996 to require facilities handling particular chemicals to plan how to prevent and address chemical accidents. The PSM and RMP regulations each apply to processes involving a specified list of chemicals above threshold quantities, and require covered facilities to take certain steps to prevent and prepare for chemical accidents. However, neither OSHA’s PSM regulations nor EPA’s RMP regulations cover ammonium nitrate. The Emergency Planning and Community Right-to-Know Act of 1986 (EPCRA) establishes authorities for emergency planning and preparedness and emergency release notification reporting, among other things. Under section 312 of EPCRA and EPA regulations, facilities with certain hazardous chemicals in amounts at or above threshold levels— including ammonium nitrate in some circumstances—are required to annually submit chemical inventory forms to state and local authorities to help emergency response officials prepare for and respond to chemical incidents. For purposes of enhancing chemical facility security, the Department of Homeland Security (DHS) Chemical Facility Anti-Terrorism Standards (CFATS) program requires facilities possessing certain chemicals at or above threshold quantities–including some types of ammonium nitrate–to submit reports to DHS with information about the facility and the regulated chemicals present on site. Among other things, DHS collects information on the quantities of certain hazardous chemicals held at facilities, the location of the facilities, and their industry codes. DHS set different threshold quantities for reporting based on the type of ammonium nitrate and the type of security risk presented (see table 1). Not all facilities with ammonium nitrate, however, are required to file CFATS reports with DHS. First, facilities are only required to report if they are holding amounts equal to or greater than threshold quantities of specific types of ammonium nitrate. Also, DHS does not require certain agricultural producers to report their chemical holdings to DHS. In addition, DHS’s reporting threshold for ammonium nitrate fertilizer only applies to quantities held in transportable containers such as cylinders, bulk bags, bottles (inside or outside of boxes), cargo tanks, and tank cars. Finally, there are several statutory exemptions to CFATS requirements. Specifically, CFATS does not apply to public water systems or treatment works, any facility that is owned or operated by the Department of Defense or the Department of Energy, facilities regulated by the Nuclear Regulatory Commission, or facilities covered by the Maritime Transportation Security Act of 2002 administered by the Coast Guard. Other federal agencies regulate different aspects of the use of hazardous chemicals. For example, the Department of Transportation regulates the transport of hazardous materials, the Coast Guard inspects containers of hazardous materials at ports and waterways, and the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) in the Department of Justice regulates the manufacture, distribution, and storage of explosive materials, including blasting agents and other explosive materials containing ammonium nitrate. State and local government agencies are also involved in regulating hazardous chemical facilities under federal laws and their own state or local laws. Federal laws may authorize or assign state and local governments certain roles and responsibilities for overseeing chemical facilities. For example, as permitted by the OSH Act, OSHA has approved state plans that authorize about half the states to operate their own occupational safety and health programs. As a result, private sector workplaces in 21 states and Puerto Rico are regulated and inspected by state occupational safety and health agencies rather than OSHA. Similarly, EPA has delegated its authority to implement and enforce the Risk Management Program to nine states and five counties. As previously mentioned, both state and local governments play a role in implementing EPCRA, which requires covered facilities to report basic information about their hazardous chemical inventories to certain state and local authorities, including estimates of the amounts of chemicals present at facilities. In addition, state and local governments may establish and enforce their own laws, regulations, or ordinances to protect the public from chemical accidents. For example, state and local governments may adopt and enforce fire codes or zoning laws that specify how far chemical facilities must be located from residential areas. The Executive Order issued on August 1, 2013 established a Chemical Facility Safety and Security Working Group co-chaired by the Secretary of Homeland Security, the Administrator of EPA, and the Secretary of Labor. The Executive Order includes directives for the working group to: improve operational coordination with state and local partners; enhance federal agency coordination and information sharing; modernize policies, regulations, and standards; and work with stakeholders to identify best practices. The order includes tasks focused specifically on ammonium nitrate. Specifically, it directs the Secretaries of Homeland Security, Labor, and Agriculture to develop a list of potential regulatory and legislative proposals to improve the safe and secure storage, handling, and sale of ammonium nitrate. In addition, the Department of Labor and EPA are directed to review the chemical hazards covered by the RMP and PSM regulations and determine whether they should be expanded to address additional hazards. The Organisation for Economic Co-operation and Development (OECD), an intergovernmental organization with 34 member countries, issued guidance in 2003 on the prevention of, preparedness for, and response to chemical accidents. This publication was developed with other international organizations active in the area of chemical accident safety, such as the World Health Organization. The document—OECD Guiding Principles for Chemical Accident Prevention, Preparedness and Response—includes detailed guidance for industry, public authorities, and the public on how they can help prevent chemical accidents and better respond when accidents occur. The total number of facilities in the United States with ammonium nitrate is not known because of the different reporting criteria used by different government agencies, reporting exemptions, and other data limitations. While the total number is unknown, over 1,300 facilities reported having ammonium nitrate to DHS. DHS’s data, however, do not include all facilities that work with ammonium nitrate, in part because some facilities, such as farms, currently do not have to report to DHS and, according to DHS officials, other facilities that are required to report may fail to do so. As of August 2013, 1,345 facilities located in 47 states reported to DHS under CFATS that they had ammonium nitrate.