Environmental Planning

Air Quality

Motor Vehicle Emissions Modeling

Transportation conformity requires transportation plans, programs and projects in any nonattainment area for carbon monoxide, nitrogen dioxide, particulate matter, or ozone to evaluate air quality impacts before receiving Federal approval. The Arizona Department of Environmental Quality (ADEQ) submits air quality plans to the Environmental Protection Agency (EPA) that contains an emissions inventory of all sources that emit pollutants into the air. These air quality State Implementation Plans (SIPs) contain a cap on vehicle emissions, this limit on emissions is referred to as a Motor Vehicle Emissions Budget (MVEB). The EPA determines whether any MVEB established in an SIP is adequate for transportation conformity purposes, a list of approved budgets can be found on EPA's website.

The EPA also approves the type of emissions models that can be used to estimate transportation related emissions for a "regional conformity analysis" and project level "hot spot" analysis. ADOT Air Quality staff uses these models for regional and project level conformity analysis when necessary and also provides local agencies with specific motor vehicle registration data required to run these models, for more information contact jjoo@azdot.gov.

Recent EPA Guidance on emissions models used for transportation:

  • For tailpipe emissions: Motor Vehicle Emission Simulator model (currently MOVES2014a) is required for regional emissions analyses for transportation conformity determinations “regional conformity analyses” as of March 2, 2013 and for Project level “hot spot” analysis as of Dec. 20, 2012. The EPA released MOVES2014a in November, 2016. On August 28, 2018 the EPA released MOVES2014b, this is the latest version of MOVES that is required for regulatory transportation emissions analysis.
  • For re-entrained road dust: The EPA uses "AP-42: Compilation of Air Pollutant Emission Factors" to estimate road dust from paved and unpaved roadways. AP-42 Methods for Estimating Re-Entrained Road Dust from Paved roads 13.2.1 was updated on January 2011 and required for any conformity analysis Feb. 4, 2013. The current AP-42 Methods for Unpaved Roads can be found in section 13.2.2 last updated November 2006.
  • For air quality dispersion models: The current EPA approved models for project level emissions analysis include either AERMOD Version 18081 updated April 24, 2018, or CAL3QHCR Version 13196 updated July 15, 2013.  The Arizona Department of Environmental Quality (ADEQ) provides Guidance for Air Quality Dispersion Modeling and pre-processed Meteorological Data on their website.

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Civil Rights

Pursuant to Title VI of the Civil Rights Act of 1964, the Americans with Disabilities Act (ADA) and other nondiscrimination laws and authorities, ADOT does not discriminate on the basis of race, color, national origin, sex, age, or disability. Persons that require a reasonable accommodation based on language or disability should contact ADOT’s Civil Rights Office at civilrightsoffice@azdot.gov. Requests should be made as early as possible to ensure the State has an opportunity to address the accommodation.

De acuerdo con el Título VI de la Ley de Derechos Civiles de 1964, la Ley de Estadounidenses con Discapacidades (ADA por sus siglas en inglés) y otras normas y leyes antidiscriminatorias, el Departamento de Transporte de Arizona (ADOT) no discrimina por motivos de raza, color, origen nacional, sexo, edad o discapacidad. Las personas que requieran asistencia (dentro de lo razonable) ya sea por el idioma o discapacidad deben ponerse en contacto con la Oficina de Derechos Civiles de ADOT en civilrightsoffice@azdot.gov. Las solicitudes deben hacerse lo más antes posible para asegurar que el Estado tenga la oportunidad de hacer los arreglos necesarios.