Acid Plant New Source Review Enforcement Priority

The sulfuric and nitric acid manufacturing industry is an Environmental Protection Agency (EPA) New Source Review/Prevention of Significant Deterioration (NSR/PSD) national enforcement priority. This sector emits many thousands of tons of nitrogen oxides, sulfur dioxide, and sulfuric acid mist each year. EPA investigations into this sector have found a high incidence of NSR/PSD violations. New pollution control technology required by EPA’s settlements are both cost-effective and result in much lower emission rates from these sources than what was previously thought to be achievable.

Products Produced by this Industry:

Sulfuric acid is the largest volume chemical produced in the United States. It is used in the manufacture of phosphate fertilizer, gasoline, inorganic chemicals, soaps and detergents, and dyes. It is produced through the combustion of elemental sulfur, the decomposition of sulfuric acid containing wastes, and as a byproduct from the production of nonferrous metals such as lead, zinc, copper, molybdenum, and gold.

Nitric acid is also produced in large quantities domestically. It is used in the production of nitrogen fertilizer, explosives and munitions, and organic chemicals. All nitric acid is produced through the catalytic oxidation of ammonia.

Health and Environmental Effects of Acid Plant Emissions

Acid Plants are a significant source of sulfur dioxide, as well as nitrogen oxide, particulate matter, volatile organic emissions and other pollutants, which are associated with the following health and environmental impacts:

Sulfur dioxide (SO₂) in high concentrations can affect breathing and may aggravate existing respiratory and cardiovascular disease. Sensitive populations include asthmatics, individuals with bronchitis or emphysema, children, and the elderly. SO₂ is also a primary contributor to acid deposition, or acid rain.

Particulate matter (PM) is a mixture of solid particles and liquid droplets found in the air, such as dust, dirt, soot, or smoke. Some PM is large enough or dark enough to be seen with the naked eye, while others are so small they can only be detected using a microscope. The size of particles is directly linked to their potential for causing health problems. Small particles less than 10 micrometers in diameter pose the greatest health concerns problems due to inhalation, for example, and fine particles (less than 2.5 micrometers) are the major cause of reduced visibility (haze) in parts of the United States.

Nitrogen oxides (NO_x) can cause or contribute to a variety of health problems and adverse environmental impacts, such as ground-level ozone, acid rain, global warming, water quality deterioration, and visual impairment. Affected populations include children, people with lung diseases such as asthma, and exposure to these conditions can cause damage to lung tissue for people who work or exercise outside.

Sulfuric acid mist is a corrosive chemical and can severely burn the skin and eyes. It may cause third degree burns and blindness on contact. Exposure to sulfuric acid mist can irritate the eyes, nose, throat and lungs, and at higher levels can cause a buildup of fluid in the lungs (pulmonary edema). Asthmatics are particularly sensitive to the pulmonary irritation. Repeated exposures may cause permanent damage to the lungs and teeth. More information on the effects exposure to sulfuric acid and acid mist, please visit the Agency for Toxic Substances and Disease Registry’s Health Statement on Exposure to Sulfuric Acid.

Nitrous Oxide (N₂O) is a potent greenhouse gas with an atmospheric lifetime of approximately 120 years. Nitrous oxide is about 310 times more effective in trapping heat in the atmosphere than CO₂ over a 100-year period. The primary sources of human-influenced emissions of nitrous oxide are agricultural soil management, animal manure management, sewage treatment, mobile and stationary fuel combustion, adipic acid production, and nitric acid production. Nitrous oxide is also emitted naturally from a wide variety of biological sources.