--- title: Audit, Compliance and Risk Blog | STP | NHTSA description: NHTSA | STP's blog giving insight into audit, compliance and risk issues for EHS, business and accounting. --- [![Specialty Technical Publishers](https://blog.stpub.com/hubfs/STP-logo-white-orange.png)](http://www.stpub.com/) - [My Account](http://stponline.stpub.com) - 1-800-251-0381 # Audit, Compliance and Risk Blog ## [EPA estimates that hundreds of thousands of diesel trucks have been modified to defeat Clean Air Act emission limits](https://blog.stpub.com/epa-estimates-that-hundreds-of-thousands-of-diesel-trucks-have-been-modified-to-defeat-clean-air-act-emission-limits) Posted by [Jon Elliott](https://blog.stpub.com/author/jon-elliott) on Mon, Jan 25, 2021 - [Tweet](https://twitter.com/share) [![](https://blog.stpub.com/hubfs/group-of-trucks-parked-in-row.jpg) ](https://blog.stpub.com/epa-estimates-that-hundreds-of-thousands-of-diesel-trucks-have-been-modified-to-defeat-clean-air-act-emission-limits) The Clean Air Act (CAA) authorizes the Environmental Protection Agency (EPA) to set emission standards for motor vehicles and engines. Although the primary focus is on Corporate Average Fuel Economy (CAFÉ) standards for new vehicles, set jointly by EPA and the Department of Transportation’s (DOT’s) National Highway Traffic Safety Administration (NHTSA) (I’ve discussed ongoing disputes about the latest CAFÉ standards several times, including [HERE](https://blog.stpub.com/feds-issue-nationwide-motor-vehicle-greenhouse-gas-standards-and-declare-californias-standards-to-be-preempted)), EPA and states also have authority over post-sale “aftermarket” equipment and modifications to vehicles. [Read More](https://blog.stpub.com/epa-estimates-that-hundreds-of-thousands-of-diesel-trucks-have-been-modified-to-defeat-clean-air-act-emission-limits) 0 Comments [Click here to read/write comments](https://blog.stpub.com/epa-estimates-that-hundreds-of-thousands-of-diesel-trucks-have-been-modified-to-defeat-clean-air-act-emission-limits#comments-listing) Tags: [EPA](https://blog.stpub.com/topic/epa), [CAA](https://blog.stpub.com/topic/caa), [CAFÉ](https://blog.stpub.com/topic/café), [NHTSA](https://blog.stpub.com/topic/nhtsa), [COC](https://blog.stpub.com/topic/coc), [AECDs](https://blog.stpub.com/topic/aecds), [DOT's](https://blog.stpub.com/topic/dots) [All posts](https://blog.stpub.com/all) ### Follow Me ### Subscribe by Email ### Browse by Topic Area - [Accounting & Tax ](https://blog.stpub.com/topic/accounting-tax) - [Business & Legal ](https://blog.stpub.com/topic/business-legal) - [Corporate Governance  ](https://blog.stpub.com/../?Tag=Corporate+Governance) - [Environmental ](https://blog.stpub.com/../?Tag=Environmental) - [Global ](https://blog.stpub.com/../?Tag=Global) - [Health & Safety ](https://blog.stpub.com/topic/health-safety) - [Internet ](https://blog.stpub.com/../?Tag=Internet) - [Transportation ](https://blog.stpub.com/../?Tag=Transportation) ### Browse by Tag - [Environmental (344)](https://blog.stpub.com/topic/environmental) - [Business & Legal (309)](https://blog.stpub.com/topic/business-legal) - [Environmental risks (300)](https://blog.stpub.com/topic/environmental-risks) - [Health & Safety (296)](https://blog.stpub.com/topic/health-safety) - [EPA (283)](https://blog.stpub.com/topic/epa) - [Terms & Conditions](https://stphub.stpehs.com/wp-content/uploads/2021/01/STP-Terms-of-Use-Dec-20.pdf) - [Privacy Policy](https://stphub.stpehs.com/wp-content/uploads/2020/12/STP-Privacy-Policy.pdf) - [License Agreement](https://stphub.stpehs.com/wp-content/uploads/2021/01/STP-License-Agreement-Dec-20.pdf) - [Sitemap](http://stpub.com/sitemap) - [Support](http://stpub.com/support) © 2021 STP ComplianceEHS - All rights reserved