Spanish views from a small town

There is no question that car emissions pollute cities. Both diesel and gasoline pollute, though in different ways, with different particles. Yet, diesel cars have long been touted as cleaner than gasoline because they emit less carbon dioxide. The only problem is that they emit more nitrogen oxides and particulates, which, while not adding to the total carbon dioxide causing global warming, are harmful to people's health, especially when concentrated in urban areas. Many European cities are now legislating against diesel engines, and the older ones are being banned. Madrid and Barcelona will soon ban all diesel cars in upcoming years. So, where's the problem? The problem is that, until a couple of years ago, people were urged to buy diesel cars precisely because they don't emit as much carbon dioxide. So, while more expensive than gasoline cars at the beginning by a couple of thousand euros, more or less, diesel car owners were, and are, compensated by better mileage a...