Roadside Inspection Program Helps Keep Air Pollution in Check

State and consumer efforts have cut black carbon by 90%

Californians have made significant progress in reducing our exposure to harmful air pollutants over the past few decades with the help of regulations and programs based on sound science. In fact, according to the California Air Resources Board, black carbon has been reduced by 90%, and the number of stage one and two smog alerts dropped from 239 in 1967 to zero in 2016.

Part of that success is owed to the Bureau of Automotive Repair and its Roadside Inspection Program, which audits the emissions of vehicles while they are in use on California roads. The data collected from roadside surveys provides an overview of the vehicles’ emissions to help ensure the state is meeting federal standards for reducing ozone-forming pollution generated by motor vehicles. The data is compared to the results of vehicles of the same make, model, and year tested at licensed Smog Check stations.

Roadside surveys are one of the most effective ways of determining the success of the Bureau’s Smog Check Program, which was launched in 1984 and has become a model for other countries. The roadside surveys are similar to Smog Check inspections conducted at licensed Smog Check stations.

Where are the surveys done?

The surveys are performed in the areas of the state with the poorest air quality, including the Central Valley, the San Francisco Bay Area, the greater Los Angeles area, Inland Empire, and San Diego area. The Bureau randomly selects ZIP codes in these areas and then identifies suitable sites where surveys can be safely conducted. The Bureau’s roadside teams survey thousands of vehicles in more than 250 cities across the state each year.

How do the surveys involve consumers?

A California Highway Patrol officer is present during these roadside surveys to monitor traffic and to safely direct vehicles into the survey lane. Specially trained BAR employees with valid Smog Check licenses perform the surveys using portable inspection equipment. The survey takes less than 10 minutes and is always voluntary. The information is only used for program evaluation purposes as a means to continually improve Smog Check efforts in California. There are no repair requirements or consequences for vehicles that produce excess emissions during the survey, and the results do not affect the vehicle’s Smog Check record or substitute for a vehicle’s official Smog Check inspection. Consumers who agree to participate will receive a report detailing the results for informational purposes, and will drive away knowing they have played a role in keeping California’s air clean!

For more information on the Bureau’s programs, including the Roadside Inspection Program, visit

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