In California Building Industry Association v. Bay Area Air Quality Management District, the Supreme Court today limits the analysis of proposed projects that agencies must do under the California Environmental Quality Act (CEQA).  In the context of a challenge to air pollutant “thresholds of significance” that had been adopted by the Bay Area Air Quality Management District in response to state legislation addressing greenhouse gases, the court’s unanimous opinion by Justice Mariano-Florentino Cuéllar invalidates in part administrative guidelines issued by the California Natural Resources Agency.  Doing so gives new life to the challenge to the thresholds, a challenge which the Court of Appeal had rejected.

The court holds that — except for certain airport, school, and housing projects, and for certain risks like noise, hazardous waste, and wildland fires  — agencies “generally are not required to analyze the impact of existing environmental conditions on a project’s future users or residents.”  The court also states, however, that “when a proposed project risks exacerbating those environmental hazards or conditions that already exist, an agency must analyze the potential impact of such hazards on future residents or users.  In those specific instances, it is the project’s impact on the environment — and not the environment’s impact on the project — that compels an evaluation of how future residents or users could be affected by exacerbated conditions.”

The court reverses the First District, Division Five, Court of Appeal.