Support for the Navajo Nation Emissions Inventory

The Navajo Nation Environmental Protection Agency (NNEPA) regulates sources of air pollution on the Navajo Nation through its Navajo Air Quality Control Program (NAQCP). For administrative purposes, NNEPA divides the Nation into 110 areas, referred to as “chapters.” To ensure the quality and safety of air on the Navajo Nation, the NAQCP monitors and analyzes air quality data to establish existing air quality conditions and protect air quality by regulating air pollution sources. NAQCP last developed an emissions inventory for year 2005 and sought ERG’s support in conducting an inventory of stationary sources on the Navajo Nation for the year 2023. 

Utilizing permit reviews, emissions estimations tools, and GIS technology for mapping point sources emissions, ERG staff developed a comprehensive inventory of 2023 stationary sources emissions on the Navajo Nation that included criteria and hazardous air pollutants across all 110 chapters. Compared to the 2005 base year, the 2023 inventory of emissions data was more refined and comprehensive, with increased coverage of: 

• Point sources, including facilities with Title V permits, minor source operating permits, and/or Tribal New Source Review registrations.
• Nonpoint area sources, with emissions at the chapter level.
• Nonpoint area source pollutants, including hazardous air pollutants, greenhouse gases, and hydrogen sulfide.
• Nonpoint area source categories, including newer and expanded source categories.