A USDOT University Transportation Center

Vehicle Inspection and Maintenance (I/M) Programs

Vehicle emissions inspection and maintenance (I/M) programs allow for the effectiveness of a vehicle’s emissions control system to be periodically inspected.1 Vehicles that fail inspection must be repaired and retested to meet the program’s requirements. These programs can be implemented by state and local governments to identify cars and trucks with high emissions that need to be repaired. I/M programs are mandated by amendments made to the Clean Air Act in 1990 that requires I/M programs for certain areas depending on ozone levels, air quality status, and population density.

Considering this strategy will help achieve the goal of the following objectives

  • Less Contamination
  • Less Emissions
  • Less Traffic Noise
  • Connectivity and Inclusion
  • Healthy Destinations
  • Less Traffic Violence
  • Active Transportation
  • Green Space

Transportation lifecycle phases

This strategy is associated with the following transportation lifecycle phases:

  • Construction
  • End of Life
  • Maintenance
  • Material Selection
  • Operations
  • Policy and Planning
  • Project Development

Who's involved

  • Automakers
  • Automobile repair shops
  • Car owners
  • Local governments
  • Policymakers
Vehicle emissions inspection and maintenance (I/M) programs allow for the effectiveness of a vehicle’s emissions control system to be periodically inspected.1 Vehicles that fail inspection must be repaired and retested to meet the program’s requirements. These programs can be implemented by state and local governments to identify cars and trucks with high emissions that need to be repaired. I/M programs are mandated by amendments made to the Clean Air Act in 1990 that requires I/M programs for certain areas depending on ozone levels, air quality status, and population density.

How it Helps

Regular emissions inspections will help vehicles reach the Environmental Protection Agency’s vehicle emission standards and comply with federal clean air requirements. I/M programs are expected to reduce vehicle emissions and improve air quality by lowering carbon monoxide, carbon dioxide, particulate matter, and other pollutant levels.

Implementing

Equity Concerns:
One potential downside of implementing I/M programs is that these programs can be regressive by disproportionately impacting lower-income car owners.2 These individuals are more likely to drive older vehicles with less advanced vehicle technology that are more likely to fail an emissions inspection. In addition, these individuals may be less able to make repairs to their vehicles. Therefore, I/M programs should be implemented in a way that does not worsen disparities.

Examples

1) Texas I/M Program

In Texas, the vehicle emissions inspection program is implemented in 17 counties and is operated by the Texas Department of Public Safety in conjunction with the Texas Commission on Environmental Quality. The program requires annual inspections of gas-powered vehicles 2-24 years old and targets nitrogen oxides, volatile organic compounds, and carbon monoxide emissions.

https://www.tceq.texas.gov/airquality/mobilesource/im.html

1. EPA. (2021). Overview of Vehicle Inspection and Maintenance (I/M) Programs. https://nepis.epa.gov/Exe/ZyPDF.cgi?Dockey=P1013CC0.pdf
2. County Health Rankings & Roadmaps. (2020). Vehicle inspection & maintenance (I/M) programs. https://www.countyhealthrankings.org/take-action-to-improve-health/what-works-for-health/strategies/vehicle-inspection-maintenance-im-programs