# National Emission Standards for Hazardous Air Pollutants for Source Categories
> **Rule** · — · Published 2003-05-06 · 68 FR 23898
## Document
- **Document number:** 03-55514
- **Category:** air-emissions
- **Federal Register citation:** 68 FR 23898
- **CFR reference:** 40 CFR 63
- **Publication date:** 2003-05-06
## Source
- [Federal Register document](https://www.federalregister.gov/documents/2003/05/06/03-55514/national-emission-standards-for-hazardous-air-pollutants-for-source-categories)
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