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What is an Emissions Check?

Mary McMahon
Updated: May 17, 2024

An emissions check is a test which is performed to determine the nature of emissions produced through the process of combustion. People most commonly think of emissions checks in the context of tests performed on motor vehicles to determine whether or not they meet emissions standards set by the government. However, emissions checks can also be performed on the flue gases produced at industrial facilities, with the goal of monitoring efficiency at the facility and of determining whether or not the facility meets government standards.

During an emissions check, a device known as a sniffer is connected to an outlet for emissions like the tailpipe of a car. The device relays information about which gases and particulates are present in the emissions being produced, and in which concentrations. The device may inform the technician about whether or not the emissions being checked have passed emissions standards, or the technician may need to consult a chart of government and industry standards to put the emissions information in context.

For vehicles, an emissions check is often required before the vehicle can be registered successfully with the Department of Motor Vehicles. If the emissions are deemed to be too high, the problem causing the high emissions will need to be corrected to that the vehicle can be tested again. Emissions standards for vehicles are designed to reduce the amount of harmful emissions caused by vehicles on the road, to improve air quality standards and reduce damage to the natural environment caused by vehicle emissions.

Emissions standards for factories are also designed to reduce pollution. In regions where factories are enrolled in cap and trade systems to cut down on greenhouse gas emissions, the emissions check is used to determine where the factory falls within the framework of the system, and to see whether or not it is violating emissions standards. If a company exceeds its amount of allowed emissions, it will need to buy or trade emissions credits with another company. Companies with emissions checks which indicate that they are emitting less than the legal limit will be given credits to trade or sell.

If people believe that the results of an emissions check are incorrect, they may be able to challenge the results or request a retest. Performing emissions checks properly can be a little bit complicated, and using incorrect or improperly maintained equipment will skew the results. Until new new test results prove otherwise, however, the test results will be considered a failure of the emissions standard.

About Mechanics is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.
Mary McMahon
By Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a About Mechanics researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

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Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a...

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