# Technical Correction to the National Ambient Air Quality Standards for Particulate Matter
> **Rule** · Final rule. · Published 2017-03-20 · Effective 2017-05-19 · 82 FR 14325
## Document
- **Document number:** 2017-05474
- **Category:** air-emissions
- **Federal Register citation:** 82 FR 14325
- **CFR reference:** 40 CFR 50
- **Publication date:** 2017-03-20
- **Effective date:** 2017-05-19
- **EPA docket:** EPA-HQ-OAR-2016-0408
## Abstract

The Environmental Protection Agency (EPA) is taking final action to make a technical correction to equation 2 in appendix N to part 50, section 4.4(b) of the National Ambient Air Quality Standards (NAAQS) for Particulate Matter. Equation 2 in appendix N describes an intermediate step in the calculation of the design value for the annual PM<INF>2.5</INF> (particles with an aerodynamic diameter less than or equal to a nominal 2.5 micrometers) NAAQS. This action corrects Equation 2 to properly account for cases where a site has quarters without daily values and passes the minimum quarterly value data substitution test. This change accurately reflects the intended calculation of the annual PM<INF>2.5</INF> design value and is consistent with the text of section 4.1 in appendix N to part 50.

## Source
- [Federal Register document](https://www.federalregister.gov/documents/2017/03/20/2017-05474/technical-correction-to-the-national-ambient-air-quality-standards-for-particulate-matter)
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