The city's grid of roads, broken up by parks and green spaces, makes it the best equipped urban area to see off the emissions it produces, researchers say.
But Luton, less than 23 miles away, has been named as the UK's air pollution capital because its compact city-centre makes it hard for traffic fumes to escape the area.
The study, carried out by the universities of Leicester and Birmingham, was published this week in the l Environmental Research journal.
It analysed the UK's 146 most densely populated areas to see how efficiently they dispersed the pollution they generated from traffic, household heating, industry and other sources.
Researchers found the layout of each town made a huge difference to how much of the pollution produced lingered in the area and how much blew off into the countryside.
It is hoped the study's findings could help town planners to design cities in a way that minimises pollution.
Lead author Professor Rob MacKenzie from the University of Birmingham said: "Our new study shows how effective an area is in dispersing the pollution it produces - in terms of its layout and the types of buildings. Urban areas with green space interleaved with transport, commercial and residential areas are best," said
"Milton Keynes is top of our list with the biggest gap between the amount of pollution produced and the concentrations in the air we breathe. This reflects the way the city is laid out, with its distinctive mix of grids and roundabouts together with its parks and green spaces - which all contribute to this overall effect," he said.
"And we have Luton right down at the bottom where its compactness works against dispersion of pollution.
Stoke-on-Trent, Aldershot and Livingston in Scotland benefit greatly from having space to disperse their polluatants while Cardiff, Stevenage, Edinburgh and Motherwell are penalised by their design.
The study looked at nitrogen oxides and tiny particulates, which together are responsible for an estimated 64,000 early deaths a year in the UK from problems such as heart attacks, strokes and acute asthma attacks.
It did not look at measures taken to reduce emissions, such as good public transport and availability of cycle lanes - but rather is concerned with how efficiently the emissions that are created are dispersed, relative to their population size.
The most efficient (per capita):
The least efficient:
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