Putting an End to London's Bad Air Days

The worst levels of air pollution are generally found in Beijing, Delhi and other metropolises of the developing world, where headlong growth stirs up construction dust and energy providers still burn a lot of coal. But the air in London is dangerously polluted, too, with concentrations of nitrogen dioxide in some parts of the city measuring among the highest in the world. The foul air around Britain’s capital and other cities is a testament to the polluting power of buses, cars and trucks -- and the need for governments everywhere to keep them operating within limits.

In 2014, London’s major shopping thoroughfare, Oxford Street, was by one measure the most polluted street on Earth; by Jan. 5 of this year, parts of London had already exceeded pollution limits for all of 2017. In some neighborhoods, cyclists have taken to wearing pollution-filtration masks.