european cities plagued by air pollution crises specifically focusing on smogridden scenes of iconic urban centers such as london

european smog crisis london paris urban air pollution transportation emissions industrial building energy efficiency greenhouse gas particulate matter pm nitrogen dioxide no2 sulfur so2 ozone levels health concerns respiratory diseases asthma rates child risks cardiovascular issues premature deaths quality index environmental regulations climate change carbon footprint public awareness sustainable electric vehicles cycling infrastructure walkability renewable green roofs walls forestry city planning strategies spaces cities smart growth purification technologies