# Determination of Attainment for PM10; Columbia Falls and Libby Nonattainment Areas, Montana
> **Rule** · Direct final rule. · Published 2011-01-31 · Effective 2011-04-01 · 76 FR 5280
## Document
- **Document number:** 2011-2121
- **Category:** air-emissions
- **Federal Register citation:** 76 FR 5280
- **CFR reference:** 40 CFR 81
- **Publication date:** 2011-01-31
- **Effective date:** 2011-04-01
- **State:** MT
- **EPA docket:** EPA-R08-OAR-2010-0749
## Abstract

EPA has determined that the Columbia Falls and Libby nonattainment areas in Montana attained the National Ambient Air Quality Standard (NAAQS) for particulate matter with an aerodynamic diameter of less than or equal to a nominal ten micrometers (PM<INF>10</INF>) as of December 31, 1994.

## Source
- [Federal Register document](https://www.federalregister.gov/documents/2011/01/31/2011-2121/determination-of-attainment-for-pm10-columbia-falls-and-libby-nonattainment-areas-montana)
---
*AI Analytics · CC0 1.0*