Nitrogen Oxide

Nitrogen dioxide is a light brown gas that can become an important component of urban haze. Nitrogen oxides (NOx) usually enter the air as the result of high-temperature combustion processes, such as those occurring in automobiles and power plants.

Nitrogen dioxide plays an important role in the atmospheric reactions that generate ozone.

Sulfur Dioxide

Sulfur dioxide belongs to the family of sulfur oxide gases. These gases are formed when fuel containing sulfur (mainly coal and oil) is burned, and during metal smelting and other industrial processes. Most SO2 monitoring stations are located in urban areas. The highest monitored concentrations of SO2 are recorded in the vicinity of large industrial facilities.

Sulfur dioxide is a major precursor to PM 2.5.

Particle Pollution

“Particulate matter,” also known as particle pollution or PM, is a complex mixture of extremely small particles and liquid droplets. Particle pollution is made up of a number of components, including acids (such as nitrates and sulfates), organic chemicals, metals, and soil or dust particles.

The size of particles is directly linked to their potential for causing health problems. EPA is concerned about particles that are 10 micrometers in diameter or smaller because those are the particles that generally pass through the throat and nose and enter the lungs. Once inhaled, these particles can affect the heart and lungs and cause serious health effects. EPA groups particle pollution into two categories:

  • “Inhalable coarse particles,” such as those found near roadways and dusty industries, are larger than 2.5 micrometers and smaller than 10 micrometers in diameter.
  • “Fine particles,” such as those found in smoke and haze, are 2.5 micrometers in diameter and smaller. These particles can be directly emitted from sources such as forest fires, or they can form when gases emitted from power plants, industries and automobiles react in the air. To reduce the health problems for those living in areas with particle pollution problems, EPA established two separate numerical standards for short term and long term particle pollution. These standards determine the maximum allowable concentrations of particle pollution. The annual standard is based on particle pollution concentrations measured over 365. The daily standard is based on the average particle pollution concentrations over a 24 hour period. For both standards, regulators average air quality monitor data form the most recent three years to determine if there has been a violation of the allowable levels.

Information courtesy of the Environmental Protection Agency.

The Birmingham region’s particle pollution problem

In April of 2005, EPA determined that the Birmingham region exceeded the annual standard of particle pollution, officially declaring our air quality as unhealthy. The Agency came to the same finding for the daily standard in 2008 after it was lowered in 2006. The Clean Air Act states that these standards must be reviewed regularly to ensure that the latest scientific studies are being utilized when deciding how much pollution in the air is too much. The boundary for our non-attainment status for particle pollution was drawn by EPA around Jefferson, Shelby and a portion of Walker County. Today two of the nine air monitors routinely exceed both the annual and daily standard for particle pollution. Other monitors are on the the edge of exceeding one or both of them as well.

For more information see Clean Air for the Birmingham Area report released in October 2009 by the Southern Environmental Law Center.


Courtesy of EPA

Courtesy of EPA

Ground-level or “bad” ozone is not emitted directly into the air, but is created by chemical reactions between oxides of nitrogen (NOx) and volatile organic compounds (VOC) in the presence of sunlight. Emissions from industrial facilities and electric utilities, motor vehicle exhaust, gasoline vapors, and chemical solvents are some of the major sources of NOx and VOC.

Breathing ozone can trigger a variety of health problems including chest pain, coughing, throat irritation, and congestion. It can worsen bronchitis, emphysema, and asthma. Ground-level ozone also can reduce lung function and inflame the linings of the lungs. Repeated exposure may permanently scar lung tissue.

Ground-level ozone also damages vegetation and ecosystems. In the United States alone, ozone is responsible for an estimated $500 million in reduced crop production each year.

The ozone problem in the Birmingham regionMap provided by the Southern Environmental Law Center

The Birmingham region’s ozone levels have repeatedly exceeded federal standards over the past two decades. While the area is currently in attainment with the outdated 1997 ozone standard, it is clear that the area will fail to meet the EPA’s new standard when it goes into effect.

The EPA just announced, it is proposing to tighten the allowable ambient air levels from 75 parts per billion (ppb) to within the range of 60 to 70 ppb. In 2008, the Bush Administration lowered the standard from 84 ppb to 75 ppb, despite recommendations from public health experts (Clean Air Scientific Advisory Committee) and its own federal scientists for a standard no higher than 70 ppb  to best protect more people from breathing dirty air.

The proposal to improve the air quality standard for the sake of public health is now available for the public to submit comments.

For more information see Clean Air for the Birmingham Area report released in October 2009 by the Southern Environmental Law Center.


Mercury is a naturally occurring element that is found in air, water and soil. It exists in several forms: elemental or metallic mercury, inorganic mercury compounds, and organic mercury compounds.

Mercury is found in many rocks including coal. When coal is burned, mercury is released into the environment. Coal-burning power plants are the largest human-caused source of mercury emissions to the air in the United States, accounting for over 40 percent of all domestic human-caused mercury emissions. EPA has estimated that about one quarter of U.S. emissions from coal-burning power plants are deposited within the contiguous U.S. and the remainder enters the global cycle. Burning hazardous wastes, producing chlorine, breaking mercury products, and spilling mercury, as well as the improper treatment and disposal of products or wastes containing mercury, can also release it into the environment. Current estimates are that less than half of all mercury deposition within the U.S. comes from U.S. sources.

Mercury in the air eventually settles into water or onto land where it can be washed into water. Once deposited, certain microorganisms can change it into methylmercury, a highly toxic form that builds up in fish, shellfish and animals that eat fish. Fish and shellfish are the main sources of methylmercury exposure to humans. Methylmercury builds up more in some types of fish and shellfish than others.The levels of methylmercury in fish and shellfish depend on what they eat, how long they live and how high they are in the food chain. According the Centers for Disease Control and Prevention, almost 6% of American women carry mercury concentrations at levels considered to put a fetus at risk of neurological damage. (EPA)

Information courtesy of the Environmental Protection Agency.

Mercury problem in Alabama

Mercury is currently not regulated in our country, but that will soon change. EPA has recognized the severity of the problem and is expected to come out with some regulatory system for limiting the amount of Mercury that can be released into the air.

In the Birmingham region, over 75% of the Mercury released into the air comes from the three coal-fired power plants surrounding the community. The James Miller Plant, in north west Jefferson county was the #1 emitter of Mercury in the nation in 2007. It is unclear exactly what percentage of these emissions land in the Birmingham waterways.

In order to protect Alabamians from the dangers of Mercury exposure through the consumption of fish, the state Department of Health has imposed fish consumption limitations based on Mercury contaminations on 50 places within our state’s waters, including some waters in the Birmingham region.