Tampering with vehicle engines, including installation of aftermarket defeat devices intended to bypass manufacturer emission controls, results in significantly higher releases of nitrogen oxides and particulate matter, both of which contribute to serious public health problems in the United States, EPA said. Engine Manufacturers and automakers have also used defeat devices.

“These problems include premature mortality, aggravation of respiratory and cardiovascular disease, aggravation of existing asthma, acute respiratory symptoms, chronic bronchitis, and decreased lung function. Numerous studies also link diesel exhaust to increased incidence of lung cancer,” EPA said.