関東地方の夏季高濃度Oxの長期的濃度変動要因の検討と前駆物質濃度削減効果の予測評価

摘要

The relationship between NMHC, NOx concentrations and Ox formation has been analyzed using the data observed during 1990-2011 in the Kanto region. The relationship seemed to be clearer by removing the effect of the meteorological conditions. It showed that the status of the Kanto region has been VOC-sensitive. The relationships between the precursor concentrations and Ox formation have varied according to the three periods showing the possibility that the change in the Ox measurement methods had been affected. The change in the VOC composition produced very little change in the reactivity although aromatic compounds had significantly decreased. According to the estimation using the occurrence ratios of high Ox concentration days, a 20% reduction of the NMHC concentration based on 2009-2011 average may cut in half the number of high Ox concentration days even if the NOx concentration decrease by 20%. The NMHC concentration should be reduced by 50% in order to reduce the number of high Ox concentration days to a zero level.