Does a Surprising Rise in Pollution Mean a Return of London's Pea-Soup Fog?

Christine L. Corton writes in The New York Times about the potential return of London's infamous pea-soup fog—a combination of natural fog and "sulfur-laden smoke" from industrial chimneys and home coal fires. The culprit this time appears to come from car exhaust.

…after several decades of cleaner air, we seem to be sliding back. Motor vehicles are now the main cause of air pollution, and campaigners are trying to create some urgency around the debate to reduce car emissions. But people are as wedded to cars now as they were tied to their open fires a century or more ago.

The last recorded case of London’s "great yellow fog" was in 1962, following the adoption of a clean Air Act in 1956 that required residents to switch from coal to cleaner sources of energy, such gas or electricity. The Clean Air Act arose after a 1952 incident, which Corton describes as a "great killer fog" that lasted five days and resulted in the deaths of an estimated 4,000 people.