May 21, 2006


Photochemical Smog in 2005 Worst for Decade

Keywords: Chemicals Government 

In 2005, sufferers from eye and throat irritations numbered 1,495 across 10 prefectures, the highest level for the past 10 years, according to a report on photochemical smog released by the Japanese Ministry of the Environment in January 2006. The report shows that the adverse effects are concentrated in September, with the number of sufferers at 1,325, predominantly including elementary and junior high school students.

Warnings against photochemical oxidants, the main cause of photochemical smog formation, were issued 185 times by 21 prefectures. In Saitama Prefecture, such advisories were issued in September for the first time in four years. By prefecture, Chiba had the highest number of warnings at 28, followed by Saitama and Tokyo.

The main causative photochemical oxidants are nitrogen oxides and volatile organic compounds emitted from factories and automobiles. These pollutants react chemically with sunlight to form photochemical oxidants which increase in density on days with strong sunshine, high temperatures and very little wind.

Health problems due to photochemical smog were quite rampant in Japan in the 1970s and emission controls have since been successfully enforced by law. The hourly average peak concentrations of photochemical oxidants during the day, however, have been showing a gradual increase in recent years.

Posted: 2006/05/21 10:16:49 PM
Japanese version