It has been called an invisible epidemic. Every year, around 300,000 people in Europe die prematurely because of air pollution, according to the European Environment Agency. Those of us living in cities are particularly exposed to unsafe levels of fine particulate matter and nitrogen dioxide. The EU is trying to bring air quality closer to World Health Organization guidelines, but the political deal that has been struck includes a clause that will allow member states to delay action by up to 10 years, if specific conditions are met.