What Does Nonattainment NSR Require?

Nonattainment NSR applies to new major sources or major modifications at existing sources for pollutants where the area the source is located is not in attainment with the National Ambient Air Quality Standards (NAAQS). Nonattainment NSR requirements are customized for the nonattainment area. All nonattainment NSR programs have to require (1) the installation of the lowest achievable emission rate (LAER), (2) emission offsets, and (3) opportunity for public involvement.

What is LAER?

LAER is the most stringent emission limitation derived from either of the following:

• the most stringent emission limitation contained in the implementation plan of any State for such class or category of source; or
• the most stringent emission limitation achieved in practice by such class or category of source.

The emissions rate may result from a combination of emissions-limiting measures such as (1) a change in the raw material processed, (2) a process modification, and (3) add-on controls.

The RACT/BACT/LAER Clearinghouse (RBLC) database contains information on what has been required as LAER in air permits.

What are Emission Offsets?

Offsets are emission reductions, generally obtained from existing sources located in the vicinity of a proposed source which must (1) offset the emissions increase from the new source or modification and (2) provide a net air quality benefit. The obvious purpose for requiring offsetting emissions decreases is to allow an area to move towards attainment of the NAAQS while still allowing some industrial growth.