Forest Trail


21 results found for


National Ambient Air Quality Standards (NAAQS)

Standards established by the U.S. EPA that apply for outdoor air throughout the country. There are two types of NAAQS. Primary standards set limits to protect public health and secondary standards set limits to protect public welfare. For more information, visit our AAQS website.

Natural Sources

Non-manmade emission sources, including biological and geological sources, wildfires and windblown dust.

Naturally Occurring Asbestos (NOA)

Naturally occurring asbestos (NOA) is the six asbestos minerals that have been identified as toxic air contaminants and occur naturally in rocks and soils. During many earth-disturbing activities, asbestos minerals may be released from rocks and soils, become airborne and inhaled deep into the lung.


The National Emissions Standards for Hazardous Air Pollutants (NESHAPs) are set by the U.S. EPA for an air pollutant not covered by National Ambient Air Quality Standards that may cause an increase in fatalities or in serious, irreversible, or incapacitating illness

New Solar Home Partnership (NSHP)

Part of the comprehensive statewide solar program. The NSHP program provides financial incentives and other support to home builders, encouraging the construction of new, energy efficient solar homes that save homeowners money on their electric bills and protect the environment.

New Source Performance Standards (NSPS)

Uniform national U.S. EPA air emission standards that limit the amount of pollution allowed from new sources or from modified existing sources. For more information, see our Title V website.

New Source Review (NSR)

A Clean Air Act requirement that State Implementation Plans must include a permit review, which applies to the construction and operation of new and modified stationary sources in nonattainment areas, to ensure attainment of National Ambient Air Quality Standards. The two major requirements of NSR are Best Available Control Technology and Emission Offsets. For more information, see our New Source Review website.

New Vehicle

Any vehicle transferred with less than 7,500 miles, or any vehicle that has not yet been issued a title (regardless of mileage).

NIST Cert of Standards

The National Institute of Standards and Technology (NIST) provides standard reference materials used to confirm the accuracy and traceability of standards for calibrating instrumentation used to measure atmospheric concentrations of air pollutants.

Nitric Oxide (NO)

A Precursor of ozone, NO2 and nitrate; nitric oxide is usually emitted from combustion processes. Nitric oxide is converted to nitrogen dioxide (NO2) in the atmosphere and then becomes involved in the photochemical processes and/or particulate formation. (See Nitrogen Oxides.)

Nitrogen Oxides (Oxides of Nitrogen, NOx)

A general term pertaining to compounds of nitric oxide (NO), nitrogen dioxide (NO2) and other oxides of nitrogen. Nitrogen oxides are typically created during combustion processes and are major contributors to smog formation and acid deposition. NO2 is a criteria air pollutant and may result in numerous adverse health effects.

No-Observed-Adverse-Effect-Level (NOAEL)

A term used in risk assessment. An exposure level at which there are no statistically or biologically significant increases in the frequency or severity of adverse effects between an exposed population and a comparable non-exposed population.

No-Observed-Effect-Level (NOEL)

A term used in risk assessment. An exposure level at which there are no statistically or biologically significant difference or severity of any effect between an exposed population and a comparable non-exposed population.

Non-carcinogenic Effects

Non-cancer health effects which may include birth defects, organ damage, morbidity and death.

Non-Industrial Source

Any of a large number of sources -- such as mobile, area-wide, indirect and natural sources -- which emit substances into the atmosphere.

Non-Methane Hydrocarbon (NMHC)

The sum of all hydrocarbon air pollutants except methane. NMHCs are significant precursors to ozone formation.

Non-Methane Organic Gas (NMOG)

The sum of non-methane hydrocarbons and other organic gases such as aldehydes, ketones and ethers.

Non-Point Sources

Diffuse pollution sources that are not recognized to have a single point of origin.

Non-Road Emissions

Pollutants emitted by a variety of non-road sources such as farm and construction equipment, gasoline-powered lawn and garden equipment, power boats and outboard motors. For more information, see our offroad website.

Nonattainment Area

A geographic area identified by the U.S. EPA and/or ARB as not meeting either NAAQS or CAAQS standards for a given pollutant. For more information, visit our designated areas website.

Nonattainment Transitional

A subcategory of the nonattainment designation category for state standards that signals progress and implies the area is nearing attainment. Districts with nonattainment-transitional status may revise their attainment plans to delay adoption of control measures anticipating attainment without the measures.