June 21, 2005


Tokyo Government Identifies Factors that Increase Photochemical Oxidants

Keywords: Chemicals Local government 

The Tokyo Metropolitan Government released the final report on a two-year study of the Committee for Photochemical Oxidants Control on February 1, 2005. Photochemical oxidants are pollutants produced by photochemical reactions of atmospheric nitrogen oxides (NOx) or nonmethane hydrocarbons in the presence of the ultraviolet rays in sunlight. They cause photochemical smog, which can cause damage to the eyes and throats of people who come in contact with them, and to the leaves of plants.

In the research, the factors that increase the concentration of photochemical oxidant£ó in the Tokyo metropolitan area were identified for the first time in Japan. The results were obtained by analyzing monitoring data of atmospheric pollution in the last 27 years, focusing on the meteorological factors and causal agents.

In terms of meteorological factors, the research found that the amount of solar radiation has more damaging effects than other factors such as temperature or wind speed. It was found that as the sunlight increases, the concentration of photochemical oxidants rises. Among causal agents, as the concentration of nonmethane hydrocarbons increases in proportion to nitrogen oxide concentration, a high concentration of oxidants is more likely to be formed.

The major sources of volatile organic compounds (VOCs), including nonmethane hydrocarbons, are factories and businesses with painting or printing processes, as well as dry cleaners, gas stations and automobiles. The metropolitan government will take further measures to curb VOC emissions based on the analysis.

Posted: 2005/06/21 10:50:44 AM
Japanese version