Vehicle emissions testing: which counties require it, in which states
For each US state that runs a vehicle emissions inspection (I/M) program: which counties require testing, how often, which vehicles are exempt, and the test type — from the state environmental agency's own page, not a DMV content mill. The answer is county-level, not state-level, and it is moving: North Carolina asked EPA to remove all nineteen of its remaining counties (submitted October 2024), Texas is adding Bexar County (San Antonio) in 2026, and Colorado is changing test types in 2026. Georgia's program covers exactly 13 named metro-Atlanta counties; Texas covers 17 counties across four metros; Colorado covers all or part of 9 Front Range counties. EPA maintains no current state/county list — only technical guidance. Answers 'do I need an emissions test to register my car in [county], [state]', 'is [state] getting rid of emissions testing', and 'how old does my car have to be to be exempt in [state]'. States with no program get no record unless their agency states the absence.
2 records where two or more sources state different values. Both sides are reproduced on the record page, each with its own source and quote.
The data
| State | Counties where testing is required | Vehicles covered / exempt | Recent or pending change | Program / authority | How often |
|---|---|---|---|---|---|
| Arizona | the Phoenix and Tucson metropolitan areas | ||||
| Colorado | all or portions of Adams, Arapahoe, Boulder, Broomfield, Denver, Douglas, Jefferson, Larimer, and Weld counties | owners of gasoline-powered vehicles in the Front Range area of Colorado | Starting in 2026, these Colorado drivers will have access to self-service kiosks for On-Board Diagnostics (OBD) emissions tests that will be available 24/7 at convenient locations | Automobile Inspection and Readjustment (AIR) program | |
| Georgiasources differ | 13-county Atlanta Metropolitan Area (Cherokee, Clayton, Cobb, Coweta, DeKalb, Douglas, Fayette, Forsyth, Fulton, Gwinnett, Henry, Paulding or Rockdale) | gasoline-powered passenger vehicles registered in the 13-county Atlanta Metropolitan Area | Georgia’s Clean Air Force | ||
| Illinois | these areas of Illinois | vehicle emissions inspection program | |||
| Nevada | the urban areas of Clark or Washoe county | Gasoline powered (regardless of weight or size) | Nevada Emission Control Program | emission tests each year for qualifying vehicles | |
| North Carolina | 19 counties | cars and light-duty trucks | Section 12.7 of Session Law (S.L.) 2023-134 (House Bill 259) of the 2023 session of the North Carolina General Assembly, passed into law October 3, 2023, will remove 18 counties from the I&M program. Section 12.13.(b) of Session Law (S.L.) 2026-41 (Senate Bill 257) of the 2026 session of the North Carolina General Assembly, passed into law July 7, 2026, will also remove Mecklenburg County from the program. | Inspection / Maintenance (I/M) Program | emission systems tests for cars and light-duty trucks as part of the annual safety inspection in 19 counties |
| Texassources differ | Brazoria, Collin, Dallas, Denton, Ellis, El Paso, Fort Bend, Galveston, Harris, Johnson, Kaufman, Montgomery, Parker, Rockwall, Tarrant, Travis, and Williamson Counties | Beginning November 1, 2026, motorists with vehicles registered in Bexar County will not be eligible to renew their vehicle's annual registration if the vehicle has not passed its annual emissions inspection | vehicle emissions inspection program | annual emissions inspection | |
| Washington | Washington's vehicle emission check program ended Jan. 1, 2020 | vehicle emission check program |
Where this came from
Every record above links the page it was taken from and quotes the sentence that states it. These are the 10 sources this dataset was assembled from.
- myazcar.comhttps://www.myazcar.com/
- cdphe.colorado.govhttps://cdphe.colorado.gov/apcd/motor-vehicle-emissions
- cleanairforce.comhttps://cleanairforce.com/frequently-asked-questions
- epd.georgia.govhttps://epd.georgia.gov/air-protection-branch/air-branch-programs/mobile-and-area-sources-program/inspection-and
- epa.illinois.govhttps://epa.illinois.gov/topics/air-quality/mobile-sources/vehicle-emissions-testing.html
- dmv.nv.govhttps://dmv.nv.gov/emission.htm
- deq.nc.govhttps://deq.nc.gov/about/divisions/air-quality/motor-vehicles-air-quality/inspection-maintenance-program
- tceq.texas.govhttps://www.tceq.texas.gov/airquality/mobilesource/im.html
- tceq.texas.govhttps://www.tceq.texas.gov/airquality/mobilesource/vim/overview.html
- ecology.wa.govhttps://ecology.wa.gov/Air-Climate/Air-quality/Vehicle-emissions
Machine-readable
- data.jsonThe whole dataset — every record with its source URL and source quote.
- Open Knowledge Format bundleOne JSON object per line — every record's frontmatter and quoted span exactly as it is held here, in one fetch.
- How this is made and checkedWhat "verified against source" does and does not mean.