July 18, 2016

A photochemical smog is a concentrated mass of an atmospheric pollutant called photochemical oxidants, appearing like a white fog shrouding the land when seen from a distance. The smog tends to occur on a hot summer day when the sky is clear and there is little wind.

This became an issue in Japan when the nation’s industry was operating at high capacity and car ownership grew rapidly. While occurrences have decreased since then, they have never ceased and authorities still issue alerts for their potentially serious health effects.