UPDATE:  April 13, 2012:  On June 2, 2010, the Bay Area Air Quality Management District’s Board of Directors unanimously adopted thresholds of significance to assist in the review of projects under the California Environmental Quality Act.  These Thresholds are designed to establish the level at which the District believed air pollution emissions would cause significant environmental impacts under CEQA and were posted on the Air District’s website and included in the Air District's updated CEQA Guidelines (updated May 2011). 

On March 5, 2012 the Alameda County Superior Court issued a judgment finding that the Air District had failed to comply with CEQA when it adopted the Thresholds.  The court did not determine whether the Thresholds were valid on the merits, but found that the adoption of the Thresholds was a project under CEQA.  The court issued a writ of mandate ordering the District to set aside the Thresholds and cease dissemination of them until the Air District had complied with CEQA.  The Air District has appealed the Alameda County Superior Court’s decision.  The appeal is currently pending in the Court of Appeal of the State of California, First Appellate District. 

In view of the court’s order, the Air District is no longer recommending that the Thresholds be used as a generally applicable measure of a project’s significant air quality impacts.  Lead agencies will need to determine appropriate air quality thresholds of significance based on substantial evidence in the record.  Although  lead agencies may rely on the Air District’s updated CEQA Guidelines (updated May 2011) for assistance in calculating air pollution emissions, obtaining information regarding the health impacts of air pollutants, and identifying potential mitigation measures, the Air District has been ordered to set aside the Thresholds and is no longer recommending that these Thresholds be used as a general measure of project’s significant air quality impacts.  Lead agencies may continue to rely on the Air District’s 1999 Thresholds of Significance and they may continue to make determinations regarding the significance of an individual project’s air quality impacts based on the substantial evidence in the record for that project. 

Various tools and resources are available on this website to assist local jurisdictions in applying the Air District’s CEQA Guidelines.