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New Hampshire Department of Environmental Services


The air we breathe can become contaminated with pollutants from a variety of natural and manmade sources. Since federal legislation involving ambient air quality was enacted in 1970, air pollution control has focused on "criteria" air pollutants, including sulfur dioxide (SO2), carbon monoxide (CO), nitrogen oxides (NOx), ozone (O3), lead (Pb), and particulate matter (PM), which are primarily by-products of burning fossil fuel. In recent years, however, the focus of ambient air quality has begun to shift and now includes not only criteria air pollutants, but "toxic" air pollutants. Toxic air pollutants are also referred to as "air toxics" or "hazardous air pollutants" (HAPs) and are defined as those pollutants that are suspected of causing cancer or other serious health conditions, or to cause adverse environmental impacts.

In general, the toxic air pollutants of greatest concern are those that are released to the air in large enough amounts to create a risk to human health and that have the potential to reach many people. Toxic air pollutants may exist as particulate matter or as vapors. Examples of air toxics typically associated with particulate matter include heavy metals such as cadmium, mercury, chromium, and lead compounds, and semivolatile organic compounds such as polycyclic aromatic hydrocarbons (PAHs), which are generally emitted from the combustion of wastes and fossil fuels. Examples of gaseous toxic air pollutants include benzene, toluene and xylenes, which are found in gasoline; perchloroethylene, which is used in the dry cleaning industry; and methylene chloride, which is used as a solvent by a number of industries.

An Air Toxics Control Program for New Hampshire was established in 1987 to help protect the health of New Hampshire residents and preserve the environment. This program, together with the US EPA program to control hazardous air pollutant emissions as set forth in Section 112 of the 1990 Clean Air Act Amendments (CAAAs), is designed to reduce the emissions and ambient air impacts of a number of toxic air pollutants likely to be emitted by businesses and industry in the state.

Title III of the CAAAs identified 188 hazardous air pollutants (HAPs) that are likely to have the greatest impact on ambient air quality and human health on a national level. The list of HAPs regulated by EPA is published in Section 112 of the CAAAs.

The NHDES Air Toxics Control Program regulates HAP emissions, as well as over 800 regulated toxic air pollutants (RTAPs), which have a health-based risk to humans. The aim of the regulatory program is to protect public health and the environment by establishing ambient air limits (AALs) and requiring businesses in the state to reduce their emissions of any of the RTAPs, such that they do not impact the downwind air quality at levels that may exceed the established AALs. The list of RTAPs, published in NH Code of Administrative Rules Chapter Env-A 1400 Regulated Toxic Air Pollutants includes: (1) those compounds listed as HAPs by EPA; (2) those chemical substances for which a threshold limit value (TLV) has been established by the American Conference of Governmental Industrial Hygienists (ACGIH); and (3) those compounds not otherwise included that are regulated by the Occupational Safety and Health Administration (OSHA). The AALs are reviewed and updated every year as new scientific data on toxicity becomes available.

Additional New Hampshire Strategies to Control Emissions of Toxic Air Pollutants

NH Mercury Reduction Strategy
Mercury is a persistent, bioaccumlative toxic pollutant that can cause numerous harmful effects in plants, animals, and humans. In 1998, the State released the New Hampshire Mercury Reduction Strategy, which called for a 50 percent reduction in mercury emissions from sources in New Hampshire by the year 2003 and ultimately a virtual elimination of all harmful anthropogenic mercury releases to the environment. The state implemented a number of the recommendations in the Strategy and achieved a greater than 50 percent reduction in mercury emissions statewide between 1997 and 2003.

NH Dioxin Reduction Strategy
Dioxin is a potent animal toxicant with the potential to produce a broad range of adverse health effects, and scientific information confirms that dioxin is a human carcinogen. In March 2001, the State released the New Hampshire Dioxin Reduction Strategy Adobe Acrobat. Since then, new more stringent regulations have been implemented resulting in a decrease in the number of sources responsible for an estimated 80 percent of dioxin emissions in the state.

Toxic Air Pollutant Monitoring
In 1999, NHDES implemented a long-term monitoring program to measure actual concentrations of toxic pollutants in the outdoor (ambient) air. The monitoring program is intended to assess the air quality throughout New Hampshire in relation to established health risk benchmarks and to examine trends in toxic concentrations over time. The program includes three monitoring sites, two in urban locations, and one in a rural area.



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NH Department of Environmental Services | 29 Hazen Drive | PO Box 95 | Concord, NH 03302-0095
(603) 271-3503 | TDD Access: Relay NH 1-800-735-2964 | Hours: M-F, 8am-4pm

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