DEEP: Air Toxics - Fact Sheet Introduction

Connecticut's Management of Toxic Air Pollutants


Since 1970, the primary focus of the Clean Air Act has been the attainment of the National Ambient Air Quality Standards (NAAQS), which are standards for the protection of the public health and welfare. The Clean Air Act established the NAAQS for the six pollutants known as criteria pollutants: carbon monoxide, lead, nitrogen dioxide, ozone, particulate matter, and sulfur dioxide. Particulate matter NAAQS are established both for particulate matter (PM10) and fine particulate matter (PM2.5).

Connecticut has diligently worked for three decades towards the attainment of the NAAQS. Considerable progress has been achieved such that Connecticut is in attainment for the lead, carbon monoxide, nitrogen dioxide, PM10 and sulfur dioxide NAAQS.

Some of Connecticut’s accomplishments include:

  • The United States Environmental Protection Agency (USEPA) recently approved Connecticut’s request to re-designate New Haven county as attainment for the particulate matter (PM10) NAAQS. This re-designation is based on ten years of monitored PM10 data.
  • In 1998, Connecticut initiated a new federal program to measure fine particulate matter (PM2.5), which was determined to be a more appropriate indicator of health-based effects. Based on data monitored in the state since 1999, Connecticut is in attainment with the fine particulate matter NAAQS, although Fairfield and New Haven counties are classified by USEPA as non-attainment as part of the New York City metropolitan non-attainment area. Connecticut is developing or has implemented plans that include programs such as diesel engine idling initiatives and cleaner fuels and engines to further reduce ambient levels of PM2.5.
  • Although Connecticut is in nonattainment for the 8-hour ozone NAAQS, ozone concentrations have been generally declining since monitoring began in 1973. In 2005, the maximum one-hour monitored value was 158 parts per billion (ppb), a 50% reduction from the maximum of 313 ppb monitored in 1973, and a 10% reduction from the maximum of 175 ppb monitored in 1995. For an 8-hour averaging period (the averaging period for the current ozone standard), the value used to determine attainment has declined by 22% (from 117 ppb to 91 ppb) between 1991 and 2005.

Connecticut’s success in attaining the PM10, carbon monoxide, lead, nitrogen dioxide and sulfur dioxide NAAQS, and its initiatives towards attainment of the PM2.5 and ozone NAAQS now provide the opportunity to address other pollutants that impact the public health and welfare. Many precursors and components of the criteria pollutants potentially could have toxic or adverse health effects. Connecticut recognized that this was an issue in the early 1980’s, and in 1986 adopted and began implementing the most comprehensive regulation controlling toxic air emissions in the United States at the time. This document describes some of the programs that are responsible for reductions of toxic air pollutants in Connecticut. Effort is now underway to revisit the air toxics issue using updated information.

CT's Management of Toxic Air Pollutants | Background Information On Air Toxics

Content Last updated November 2005