# Air Quality State Implementation Plans; Approvals and Promulgations: California; Opacity Testing of Heavy-Duty Diesel Vehicles
> **Rule** · Final rule. · Published 2022-05-10 · Effective 2022-06-09 · 87 FR 27949
## Document
- **Document number:** 2022-09727
- **Category:** air-emissions
- **Federal Register citation:** 87 FR 27949
- **CFR reference:** 40 CFR 52
- **Publication date:** 2022-05-10
- **Effective date:** 2022-06-09
- **State:** CA
- **EPA docket:** EPA-R09-OAR-2021-0452
## Abstract

The Environmental Protection Agency (EPA) is taking final action to approve a revision to the California State Implementation Plan (SIP) concerning particulate matter (PM) emissions from heavy-duty (HD) diesel vehicles. We are approving state rules that regulate PM emission sources under the Clean Air Act (CAA or the Act).

## Source
- [Federal Register document](https://www.federalregister.gov/documents/2022/05/10/2022-09727/air-quality-state-implementation-plans-approvals-and-promulgations-california-opacity-testing-of)
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