Last mentioned: Mar 20, 2026
The Trump administration EPA officially revokes the 2009 scientific finding.
Public health and environmental groups file the first lawsuit against the repeal.
24 states and 10 cities file a major challenge in the D.C. Circuit Court of Appeals.
Multi-State Lawsuit Filed
A coalition of 23 states and 14 cities sues the EPA in the D.C. Circuit Court of Appeals.
Trump Revokes Finding
The Trump administration formally terminates the 2009 conclusion to halt climate regulations.
Endangerment Finding Issued
The EPA determines greenhouse gases threaten public health, triggering Clean Air Act mandates.
Endangerment Finding Issued
The EPA under President Obama officially declares greenhouse gases a threat to public health.
A coalition of 24 states and 10 cities has filed a lawsuit against the EPA to block the repeal of the 2009 endangerment finding. The legal challenge seeks to restore the scientific foundation that allows the federal government to regulate greenhouse gas emissions under the Clean Air Act.
A coalition of 23 states and 14 cities has filed a lawsuit against the EPA to overturn the Trump administration's repeal of the 2009 endangerment finding. The legal challenge seeks to restore the scientific foundation that mandates federal regulation of greenhouse gas emissions under the Clean Air Act.
This page surfaces every story mentioning Clean Air Act across our climate coverage. We track each entity's appearance over time so readers can trace how the narrative evolves — which developments are isolated incidents, which build into longer arcs, and which reframe how operators in the space think about the entity. Story selection uses the same multi-source verification gate applied across the rest of our coverage.
Read our editorial methodology for how we identify, deduplicate, and score entity references. Our glossary defines the technical terms used across stories on this page, and our trends index contextualizes individual developments against the longer-running climate beat. Cross-entity comparisons live on our compare view.
| What you see | What it tells you |
|---|---|
| Story count | Number of distinct stories where Clean Air Act was a primary or referenced actor. |
| Recency clustering | Whether mentions are concentrated in a recent window (a news cycle) or distributed (a sustained arc). |
| Sentiment distribution | Aggregate sentiment of the stories mentioning this entity, weighted by impact score. |
| Cross-niche links | When the same entity surfaces in our sibling networks, we link to those views to enrich context. |