The number of photochemical smog keeps increasing. This year the warning of photochemical smog has been announced already in 26 prefectures. In the past, photochemical smog became serious environmental problem in the city. Afterwards, it kept decreasing by the inprovement of pollution. But lately it has happened not only in the city but also rural areas, like isolated island. In fact, the causes which photochemical smog happens seem to be different between city and rural areas.
Most of the cause chemical of photochemical smog is ozone. Ozone at the high place protects us from ultraviolet rays but ozone at the low place is harmful for us. Ozone is made by NOx and VOC which soak up ultraviolet rays and happen chemical reaction. For 30 years from 1970's, NOx and VOC has decreased. But ozone has increased from 1990's. Also there is the chance that ozone comes from China. Besides there is the research that ozone keeps increasing all in the Northern Hemisphere.
In Japan, the Ministry of environment will make committee and put together report. Yutaka Kondo, professor says " We should discuss the individual and specific factors about photochemical smog." (Asahi 2007/7/18)
0 件のコメント:
コメントを投稿