# National Ambient Air Quality Standards for Particulate Matter
> **Rule** · Final rule; availability of supplemental information and request for comments. · Published 1997-07-18 · 62 FR 38762
## Document
- **Document number:** 97-18578
- **Category:** air-emissions
- **Federal Register citation:** 62 FR 38762
- **CFR reference:** 40 CFR 50
- **Publication date:** 1997-07-18
- **EPA docket:** AD-FRL-5725-4
## Abstract

EPA is announcing the availability of certain laboratory and field test data, and related reports associated with the development of the reference method (Appendix L of 40 CFR part 50) for measuring PM<INF>2.5</INF> in the ambient air. Because these data were collected, by necessity, during and after the close of the public comment period on the proposed revisions to the national ambient air quality standards for particulate matter and thus, were not available for placement in Docket No. A-95-54 until late in the rulemaking process, EPA is announcing a supplemental comment period for the limited purpose of taking comments on these field and laboratory test results only.

## Source
- [Federal Register document](https://www.federalregister.gov/documents/1997/07/18/97-18578/national-ambient-air-quality-standards-for-particulate-matter)
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