[self_buddliea]

From the article: "Drawing more people into cities could help significantly shrink the country’s overall greenhouse gas emissions. Low-density developments produced nearly four times the greenhouse gas emissions of high-density alternatives, with research finding that doubling urban density can reduce carbon pollution from household travel by nearly half and residential energy use by more than a third."

This refers to the overall volume of pollution, but not the concentration of pollution in a particular location. If you're from the UK you've likely heard about Ella Adoo-Kissi-Debrah, who tragically died aged nine in 2013 after an asthma attack. Last year a coroner's verdict was given stating pollution played a part in her death, specifically the high levels of nitrogen dioxide. I know this is just one case, but it makes me think the fine structure of urban planning is very important in this respect.