Sac Metro Air District recommends these tools and guidance documents to assist in air quality impact analysis.
Tools: Models, Calculators & Data Files
California Emissions Estimator Model including User's Guide (Sac Metro Air District recommends using CalEEMod Version 2016.3.2 for projects being released for public review on or after January 1, 2018).
Roadway Construction Emissions Model (version 9.0, May 2018). This is a .zip file. Please save it and then open it to extract the .xlsm file. IMPORTANT NOTE: U.S. EPA approved EMFAC2017 on August 15, 2019. Version 9.0 includes emissions factors from EMFAC2017.
Version 8.1.0 included emissions factors from EMFAC2014 and was available for analysis of projects requiring federal involvement during the time period EMFAC2017 was being reviewed by U.S. EPA. Consult the Sac Metro Air District staff regarding the appropriate use of version 8.1.0 (version 8.1.0).
Harborcraft, Dredge and Barge Emission Factor Calculator for obtaining emission factors from marine equipment for planning and construction analysis (July 2017)
AERMOD meteorological data files (These are .zip files. Please save the files and then open them to extract the PFL and SFC files):
Adopted Thresholds of Significance:
Greenhouse Gas Threshold of Significance Development
Sac Metro Air District staff hosted a workshop on January 9, 2019, to discuss and receive feedback on the draft proposed update to the greenhouse gas threshold of significance for operational emissions from land development projects. Download the workshop notice, report and presentation:
NEW Sac Metro Air District staff hosted a workshop on December 9, 2019, at 10:30 a.m. to present a new proposal for greenhouse gas thresholds. The new proposal was developed after considering feedback and comments received at the January workshop. Download the workshop notice, presentation and report:
Comments are requested on the greenhouse gas thresholds by January 17, 2019.
Guidance: Protocol, Recommendations & Documents
In August 2018 the California Air Pollution Control Officers Association (CAPCOA) published Air Quality Analysis in CEQA Roadway Review to address frequently questioned topics in air quality analysis, including greenhouse gases, for roadway projects reviewed under CEQA. The guidance is intended for use by lead agencies in preparing air quality analysis and by air districts in reviewing and commenting on roadway project CEQA documents. Please note that this is not comprehensive
guidance on air quality analysis for CEQA review of roadway projects. It only
responds to common questions and current misconceptions. Air districts often
have guidance on a full range of topics in CEQA air quality analysis, which is
appropriate for overall air quality analysis in their geographic area. Please
consult any of the Sac Metro Air District staff listed below to determine the
appropriate methodology for project specific CEQA analysis.
In December 2018 the California Supreme Court issued a decision in the Sierra Club v. County of Fresno case regarding the Friant Ranch project ((2018) 6 Cal. 5th 502). The Court determined the air quality analysis include a reasonable effort to connect a project's air quality impacts to likely health consequences or explain in meaningful detail why it is not feasible to do so. This type of health analysis has not been conducted for CEQA analysis normally. Sac Metro Air District prepared Interim Guidance to address the Friant Ranch decision while a methodology is being developed to provide a standardized health related analysis.
