I shall try but please feel free to add as I'm not an expert! It's been decided that in 2019, any vehicles entering central London will need to comply with certain criteria with regards to vehicle omissions or pay hefty daily fines to travel in the area with polluting vehicles. The Mayor is running this consultation to gather opinions with a view to extending this lower emissions zone to either (a) north and south circular or (b) greater London. As i understand it, NO2 emission and particulate matter are particularly harmful to health and there is lots of research by Kings and other similar institutions describing the health impact of breathing air polluted with these emissions. There are set legal limits for these pollutants and unfortunately London regularly breaches these limits. The aim of the consultation is simply to collect people's views on extending the ultra low emissions zoning to cover a wider remit. It should be noted, there will be exceptions. So if you live in the area with one of these vehicles, you have more time to comply and so initially will mainly capture vehicles entering London from outside the area.