Air Plan Approvals; Indiana; Prong 4 (Visibility) for the 2015 Ozone National Ambient Air Quality Standard
What happened
The U.S. Environmental Protection Agency (EPA) approved a part of Indiana's State Implementation Plan (SIP) regarding "Prong 4 (Visibility)" requirements under the Clean Air Act (CAA) for the 2015 ozone National Ambient Air Quality Standards (NAAQS). This approval confirms Indiana's plan has adequate provisions to prohibit emissions interfering with visibility protection in other states' SIPs. The EPA had proposed this action on April 10, 2026, and received no adverse comments. This action was signed by Donald Trump.
Why it matters
This action ensures Indiana's air quality management program meets federal standards, specifically preventing its emissions from harming visibility in other states. It helps maintain regional air quality and fulfills Indiana's responsibilities under the Clean Air Act.
Who it affects
- ›Indiana's air quality management program
- ›U.S. Environmental Protection Agency (EPA)
- ›Any other State's SIP with visibility protection
- ›Residents in Indiana and neighboring states
The receipts are official. The summary is ours.
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