Emission control devices, like a diesel particulate filter (DPF), help prevent respiratory disease, premature death, and environmental harm. Tampering with or removing a DPF is a federal offense under the Clean Air Act.
The Environmental Protection Agency (EPA) may seek civil penalties or injunctive relief for violations of the act and regulations, and may bring cases in federal district court or through an administrative process. Violators are subject to civil penalties up to $45,268 per noncompliant vehicle or engine.
More information is available here.
If you suspect someone is tampering with an emission control device, tell the EPA by writing to: tampering@epa.gov.