COMMENT: New kind of diesel cheating rears its ugly head

Though the Volkswagen ‘dieselgate’ scandal led to a new regulatory focus on ‘real world’ emissions, the measures are being seen as only a partial solution to the wider challenge of cutting air pollution. There remains a need to address the issue of high levels of NOx (oxides of nitrogen) and PM (particulate matter) being emitted by older diesel vehicles, where matters are entirely out of vehicle (or engine) manufacturers’ hands.