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Region 7 Air Program

Serving Iowa, Kansas, Missouri, Nebraska and 9 Tribal Nations


St. Louis Inspection and Maintenance Program

The Missouri Department of Natural Resources has implemented a number of air pollution control measures to improve the air quality in the St. Louis, Missouri area. On April 5, 2000, a new, enhanced vehicle inspection and maintenance (I/M) program known as the Gateway Clean Air Program began. In August 2007, the enhanced program was replaced by the current I/M on-board diagnostic (OBD) test called the Gateway Vehicle Inspection Program. More information on the St. Louis I/M program Exit EPA Click for Disclaimer.

The I/M program is a way to check whether the emissions control system on a vehicle is working correctly. All new passenger cars and trucks sold in the United States today must meet stringent pollution standards, but they can only retain this low-pollution profile if the emission controls and engine are functioning properly. I/M is designed to ensure that vehicles stay clean in actual customer use. Through periodic vehicle checks and required repairs for vehicles that fail the test, I/M encourages proper vehicle maintenance and discourages tampering with emission control devices. Further information about I/M programs is available from EPA's Vehicle and Inspection Maintenance website.

Over the next two years the 1.3 million vehicles operating in the St. Louis area will have their first emissions test and those with excessive emissions will be identified. After the emission control devices are repaired on those vehicles that failed the test, the I/M program will reduce the amount of volatile organic compounds produced by these vehicles by 36 percent (from 2.21 grams per mile for all the vehicles operating in St. Louis to 1.41 grams per mile) and reduce nitrogen oxides by 20 percent (from 2.07 grams per mile to 1.65 grams per mile). On an average day, vehicles in the metropolitan area travel some 57 million miles. Thus, this program will help protect the health of the 1.9 million residents of the St. Louis area by reducing the amount of volatile organic compounds by some 65 tons per day.

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