New Hampshire Department of Environmental Services
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Air Quality Current Data
The table below shows current air quality concentrations at New Hampshire's air monitoring sites for two air pollutants: ground-level ozone and particle pollution (fine particles).  Full monitoring, reporting, and forecasting for ozone occurs from March through September; monitoring and reporting of fine particles occurs year-round. The information in the table is updated every hour and includes wind speed, wind direction, and outside temperatures (if data are available). A map of monitoring site locations is shown at the right.

DES operates the majority of these sites and regularly monitors data quality. The Appalachian Mountain Club (AMC) maintains three monitors in northern New Hampshire, and the Hubbard Brook Research Foundation (HBRF) maintains one station in cooperation with the EPA. The data from HBRF may be downloaded from CASTNET.

The table and map are color coded according to EPA's Air Quality Index, which relates air pollutant concentrations to health effects and recommended actions.

Health Guide and Recommended Actions

Map of Current Air Quality
(Ozone and Fine Particles)
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Range for Ozone: 0 to less than 60 parts per billion. Range for Fine Particles: 0 to less than 15.5 micrograms per cubic meter. Range for Ozone: 60 to less than 76 parts per billion. Range for Fine Particles: 15.5 to less than 35.5 micrograms per cubic meter. Range for Ozone: 76 to less than 96 parts per billion. Range for Fine Particles: 35.5 to less than 55.5 micrograms per cubic meter. Range for Ozone: 96 to  less than 116 parts per billion. Range for Particles: 55.5 to less than 140.5 micrograms per cubic meter.


Ground-level Ozone
Ground-level ozone, more commonly called smog, is measured in parts per billion (ppb). The federal health based standard for an 8-hour concentration is set at 70 ppb. Since ozone is a summertime pollutant, wintertime monitoring is limited and no wintertime forecast is provided. Full monitoring, reporting, and forecasting for ozone occurs from March through September.

The EPA established a tighter 8-hour ozone standard in October of 2015 to better protect public health. The 8-hour standard was lowered from 0.075 ppm to 0.070 ppm. For more information, please visit https://www.epa.gov/ozone-pollution.

Fine Particles
Fine particle pollution consists of both solid and liquid particles that are less than 2.5 microns in diameter (a micron is a millionth of a meter). Particle concentrations are measured in micrograms per cubic meter (ug/m3). The federal health based standard for a 24-hour concentration is set at 35 ug/m3. Monitoring and reporting of fine particles occurs year-round.

The EPA has established tighter fine particle standards to better protect public health. In 2006 the standard was lowered from 65 ug/m3 to 35 ug/m3. In 2012 the annual standard was lowered from 15.0 ug/m3 to 12 ug/m3. For more information, please visit https://www.epa.gov/pm-pollution.

Sulfur Dioxide
Sulfur dioxide (SO2) is a highly reactive gas which primarily comes from fossil fuel combustion at power plants and other industrial facilities. Sulfur dioxide concentrations are measured in parts per billion (ppb). The federal health based standard for 1-hour concentrations is set at 75 ppb. Monitoring and reporting of sulfur dioxide occurs year round.

EPA first set standards for sulfur dioxide in 1971. In June 2010 EPA established a 1-hour SO2 standard at 75 ppb to better protect public health. For more information, please visit https://www.epa.gov/so2-pollution.

Related Topics


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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