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New Hampshire Department of Environmental Services


The New Hampshire Department of Environmental Services (NHDES) operates a network of air quality monitors throughout the state to measure levels of ozone, sulfur dioxide, nitrogen dioxide, carbon monoxide, particulate matter, and a number of other pollutants in the outdoor (ambient) air. Although locations and parameters have changed over the years, the state has monitored air quality since the early 1960's. NHDES also conducts meteorological monitoring at many of these sites in order to determine the relationship between weather conditions and the behavior of these pollutants. NHDES sends air monitoring data to EPA for storage and evaluation to determine pollutant trends and to see if the levels of these pollutants exceed air quality standards. You can view these data on-line at EPA’s AirData Web site.

Air Monitoring Station in Manchester NH

Air Monitoring Station in Peterborough NH

The pictures above show actual air quality monitoring stations (note the sampling equipment on the roofs). Air quality analyzers inside the stations continuously sample ambient air and produce data on air quality. Data loggers collect this data electronically and transfer it to NHDES headquarters in Concord via telephone lines. Once at NHDES headquarters, quality assurance personnel validate the data and send it to EPA. NHDES field technicians regularly service the sites and routinely calibrate the instruments to ensure accuracy.


Ambient air quality monitoring began in New Hampshire in 1962. The first monitors were installed in Berlin as part of a study conducted by the US Public Health Service. Measured levels of hydrogen sulfide, sulfur dioxide, and particulate matter were linked to emissions from the pulp and paper industrial operations in town and resulted in the paper company installing control measures. This, in turn, resulted in improved air quality in the area.

The Air Quality Act of 1967 required the establishment of air quality control regions in the state and gave the New Hampshire Air Pollution Control Commission the authority to adopt standards for each defined control region. Given that authority, the Agency initiated an air quality monitoring network throughout the state.

With the passage of the Clean Air Act of 1970, National Ambient Air Quality Standards (NAAQS) were established for five "criteria pollutants:" carbon monoxide, nitrogen dioxide, ozone, sulfur dioxide, and particulate matter. Based on data obtained from the monitoring network, it was determined that some regions of the state did not meet the standards for sulfur dioxide and particulate matter.

To correct these problems, New Hampshire’s 1972 State Implementation Plan (SIP), required by the Clean Air Act, established a permit system to ensure that ambient air quality standards would be achieved and maintained at the required levels. It also included plans for a detailed monitoring network to record levels of the five criteria pollutants.

During that same period, based on monitoring in the state, measurements of photochemical oxidants (ozone) and carbon monoxide showed that New Hampshire had areas with high levels of these pollutants. With the passage of the Clean Air Act Amendments in 1977, New Hampshire was required to revise its SIP to ensure that all areas would be in compliance with air quality standards by 1982, or with an extension by 1987.

In the years following the 1977 Amendments, New Hampshire expanded its ambient air monitoring program to track air quality in other areas of the state. Since then, New Hampshire’s network has recorded levels that show improvements in ambient air quality for nearly all pollutants.

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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

copyright 2017. State of New Hampshire