Current Status of Ozone Control Measures in the United States and Europe and Implications for Japan

In Japan, the achievement rate of environmental standards for air pollution has been improving in recent years, but for photochemical oxidants, including ozone, improvement are required. In this study, we investigated trends in ozone counter-measures in the United States and Europe from the State Implementation Plan (SIP) and National Air Pollution Control Program (NAPCP) and examined whether there are any points recommended in Japan. The United States and Europe have different policies on environmental standards for air pollution and ozone control. In the United States, states that do not meet the environmental standards for ozone concentration are required to develop an SIP to attain the standards. There was an urgent need to find a cost-effective approach to addressing the ozone problem, and forest control measures were one of the possibilities. In Europe, the European Union has set “target values” for ozone and NAPCP does not mention forest control measures or ozone sensitivity regimes. The main focus in Europe is on the win-win solution of reducing emissions of air pollutants at the same time as greenhouse gases. Japan should consider a framework including setting feasible step-by-step goals to attain the desired standards. As ozone is greatly affected by advection, wide-regional measures against ozone precursors and prediction of the future precursor reduction and concentration are required. The preparation of an emissions inventory and estimated reduction amount is prerequisites as basic data for simulation. To achieve this, cooperation between national, local and private research institutes is crucial. Since the international community has agreed to prioritize greenhouse gas counter-measures, Japan could consider a win-win solution for both ozone and greenhouse gas reduction.