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What are Criteria Pollutants?


The Environmental Protection Agency has identified six common air contaminants that it calls "criteria pollutants." The Clean Air Act strictly controls allowable levels of these six contaminants, based on their effects on human health and the environment. The six criteria pollutants are:
  • Lead
  • Ozone
  • Carbon Monoxide
  • Nitrogen Oxides
  • Particulate matter
  • Sulfur Dioxides

The Environmental Protection Agency regulates levels of these substances based on studies examining their effects on human health or the environment. Based on the results of the studies, the Environmental Protection Agency publishes permissible levels for each of the pollutants based on the severity of its impact on people or the environment.

How Can I Find The Current Permissible Levels For Criteria Pollutants?

The Environmental Protection Agency publishes current standards for each of the criteria pollutants on its website as the National Ambient Air Quality Standards (NAAQS).

Under the Clean Air Act, there are two types of standards for criteria pollutants. The Environmental Protection Agency based the “primary standard” on studies that measure when the pollutant becomes harmful to human life, especially to sensitive individuals such as children, the elderly or people with respiratory diseases.

The Environmental Protection Agency sets “secondary standards” at the level where the contaminant affects visibility or becomes harmful to the environment. The Environmental Protection Agency also based secondary standards on controlled studies of the harmful effects of these substances.

How Are Criteria Pollutant Levels Measured?

The Environmental Protection Agency clearly spells out the permissible levels for each of the criteria pollutants, usually as PPM (parts per million by volume), micrograms per cubic meter of air (µg/m3). or PPB (parts per billion by volume), depending on the pollutant.

The Clean Air Act also specifies the permissible frequency for exceeding the limits, often expressed as the maximum number of occurrences per year, the specific elapsed time period or the annual mean.

Lead has an absolute maximum based on a three month rolling average, for example, while particle pollution has both annual and daily limits averaged over time.

The Environmental Protection Agency table published here for National Ambient Air Quality Standards (NAAQS) also includes links to information about the effects of each contaminant and the measurement protocols for both primary and secondary standards.

Are There Penalties For Emitting Criteria Pollutants?

The Environmental Protection Agency works with state and local agencies to develop plans to improve air quality by reducing the levels of the criteria pollutants and the number of times levels exceed permissible levels in a given area.

The Environmental Protection Agency Office of Enforcement and Compliance Assurance has the legal authority to impose penalties, including fines and criminal prosecution.

The regulations cover stationary sources of pollution, such as factories and buildings, as well as mobile sources such as trucks and cargo ships. Penalties and settlements are public records, and the office of Enforcement publishes a list. Recent cases have involved settlements or remediation of $63mIllion from W.R. Grace, $500,000 from Phillips 66, $200million from Alpha Natural Resources and other staggering sums. Clearly, it is expensive to violate the criteria pollutant standards.

If you have questions regarding criteria pollutants, the air permitting specialists at Talon/LPE can help. Talon’s experienced staff can discuss with you the best approach in order to follow the EPA’s standards.