Primary Standards

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Primary standards

Primary standards are numerical limits of allowable air and water pollutants designed to protect human health but not necessarily other parts of the environment . Primary standards differ from secondary standards , which are those that protect against all adverse effects on the environment, such as those on animals and vegetation. While the term primary standards usually relates to air pollution or air quality , there are federal primary standards for the drinking water supply.

The Clean Air Act is the major piece of legislation that protects and enhances the nation's air quality. As part of the act, Congress required the Environmental Protection Agency (EPA) to establish National Ambient Air Quality Standards (NAAQS) for air pollutants, which were characterized by wide dispersal and emission from many sources.

The NAAQS, or primary air quality standards, define the level of air quality to be achieved and maintained nationwide for six criteria pollutants: sulfur dioxide , carbon monoxide , nitrogen oxides , ozone , particulate matter, and lead . In general, these standards are not permitted to be exceeded more than once a year. In addition, the EPA is required to identify local hazardous air pollutants which could increase mortality or result in serious illnesses such as cancer , and establish national standards for them. Although hundreds of potentially hazardous air pollutants exist, only eight had been listed as of 1990: mercury , beryllium, asbestos , vinyl chloride , benzene , radioactive substances, coke oven emissions, and inorganic arsenic .

The Clean Air Act set a deadline of December 1987 for cities in the United States to meet federal primary standards. Some cities did meet the standards, increasing automobile emission inspections and instituting tighter regulations for incinerators, but some sixty cities could not comply. There has been a measurable increase in nitrogen oxide emissions in recent years, and more than 100 areas nationwide have exceeded standards at least part of the time for ozone and carbon monoxide levels. The EPA has estimated that 100 million people live in areas exceeding these standards. The most heavily-polluted areas of the Los Angeles Basin , Houston, and the New York corridor may take years to meet the air quality standards. Suggestions to hasten compliance have included plans to shut down industrial plants, ration gas, and restrict automobile use.

The 1990 Clean Air Act Amendments include provisions to tighten pollution control requirements in cities that have not attained the National Ambient Air Quality Standards. These provisions include, among others, requirements for stringent automobile emission standards . The new act also requires a 50 percent reduction in sulfur dioxide emissions, and it sets primary and secondary standards for dozens of chemicals that were not mentioned in the original act or amendments.

Primary standards are not consistent from country to country. For example, standards are defined for different average times, at varying numerical limits. In thirteen countries the sulfur dioxide standard ranges from 0.30 to 0.75 mg/m3 for a 30-minute average, and from 0.05 to 0.38 mg/m3 for a 24-hour average. Since pollution does not stay in once place, and since acid rain is often a source of controversy between bordering countries, the lack of international standards will continue to contribute to air pollution problems.

In the United States, concern about water pollution has resulted in higher standards for water cleanliness. These standards have been adopted by state and federal agencies, but the involvement of so many different agencies on different levels has contributed to a lack of agreement on some water standards.

The primary law to protect the integrity of the nation's water is the Clean Water Act (1972). The act requires the EPA to set water quality criteria based on the most recent scientific information. Under the Clean Water Act Reauthorization (1987), the EPA is required to publish revised water quality criteria, stress new programs to combat water pollution from toxics, and restrict waivers from national standards that had been easily obtained by discharges.

Criteria are not rules; they are a compilation of data about pollutants that can be used to formulate standards. Congress intended for the EPA to set the criteria and for the states to set the water quality standards . By 1990 the EPA had established criteria for 126 priority pollutants. Of these, 109 dealt with primary standards and thirty-four with secondary standards. But although these criteria have been published, few states have actually established standards for toxic pollutants or have incorporated these standards into the regulation of toxic discharge .

Under the Safe Drinking Water Reauthorization Act (1986), the EPA is not only required to set standards for contaminants in drinking water, but it also must monitor public drinking water for unregulated contaminants and set deadlines for the issuance of new standards. By 1990, the EPA had set primary standards for drinking water that covered the inorganic chemicals arsenic, barium, cadmium , chromium, lead, mercury, nitrate, selenium, silver, and fluoride. Primary drinking water standards are measured in terms of maximum contaminant levels (MCLs), which are the maximum permissible level of a contaminant in water at the tap; they are health related and legally enforceable.

Organic chemicals regulated by primary standards for drinking water include the pesticides Endrin, Lindane, Methoxychlor, and Toxaphene ; the herbicides 2,4-D and 2,4,5-T Silvex; and the organics benzene, carbon tetrachloride, p-dichlorobenzene, 1,2-dichlorobenzene, 1,2-dichloroethane, 1,1-dichloroethylene, 1,1,1-trichloroethane, trichloroethylene, vinyl chloride, and an organic compound referred to as total trihalomethanes . Microbiological standards for drinking water have been set for coliform bacterium such as Escherichia coli , which is present in sewage and which can cause gastroenteric infections, dysentery, hepatitis, and other diseases. Standards have also been set for turbidity, the murkiness of treated water that can interfere with disinfection processes. Radionuclides regulated by primary standards include beta particles and photon activity, gross alpha particles, and Radium-226 and -228.

As is the case with primary standards for air quality, an international comparison of primary standards for drinking water reveals a collection of confusing numbers. While the United States and Canada seem to agree on standards for organic compounds, this is where the similarity ends. As of 1990, the Canadian government had no primary drinking water standards for radionuclides other than radium, and it had not set primary standards for volatile organic chemicals such as benzene and vinyl chloride. By 1990, the European Economic Community had set primary drinking water standards only for total pesticides and trihalomethanes. The World Health Organization (WHO) has recommended primary standards only for the organics 2,4-D, methoxychlor, and trihalomethanes, beta and alpha radionuclides, and five of the eight volatile organic chemicals regulated in the United States.

In the United States, there is evidence that primary standards regarding air and water pollutants have had some impact on air and water quality. Some of the nation's surface waters have improved since the implementation of the Clean Water Act. Coliform bacteria counts and dissolved solids have been reduced, and dissolved oxygen levels have increased enough to permit the reestablishment of plants and animals that had died out in polluted waters.

Air quality standards have led to an overall 20 percent reduction in emissions of particulates, sulfur dioxide, and carbon monoxide during the 1980s. Los Angeles, which suffers as much or more than any American city from air pollution, has proposed an air quality plan that would surpass the EPA's standards, requiring lifestyle changes to help combat air pollution.

Implementing laws and regulations to enforce water and air standards that will protect the health of humans will be expensive: The yearly price tag just for implementation of the Clean Air Act of 1990 is estimated to be $25 billion. But many believe the savings in health costs and environmental damage to be incalculable.

See also Air pollution index; Air Quality Control Region; Air quality criteria; Attainment area; Nitrates and nitrites; Nonattainment area; Radioactive waste; Safe Drinking Water Act; Sewage treatment; Toxic substance

[Linda Rehkopf ]



Freeman, M. Air and Water Pollution Regulation: Accomplishments and Economic Consequences. Westport, CT: Greenwood Publishing Group, 1993.

Harte, John, et al. Toxics A to Z. Berkeley: University of California Press, 1991.

van der Leeden, F., et al. The Water Encyclopedia. Chelsea, MI: Lewis Publishers, 1990.