What does living sustainably mean? It means we need to decrease our dependence on fossil fuels (and yes, that includes diesel) right now. It is true that diesel vehicles have a better fuel economy than their gasoline counterparts and are reasonably priced. And yes, in the UK, 50 percent of the cars are diesel, but diesel is not without negative consequences. A recent report (Clean Air London Group, 2015), found that diesel automobiles emit four times more nitrogen dioxide pollution (a component of ground level ozone) and 22 times more particulate matter (PM), which are small solids that can penetrate the lungs, brains and even the heart. Ground-level ozone and PM are the two pollutants the EPA tracks to ascertain the air quality. When a code orange or code red day is announced, it denotes high levels of ozone and PM. Regulation is therefore required for diesel automobiles — and all automobiles — unless we want to move back to the days when air pollution was rampant.