Achievability of Ozone Air Quality Standard

22. Since ozone is not emitted directly into the atmosphere to any significant extent, progress towards meeting the proposed Standard can only be achieved by reducing emissions of its precursors, volatile organic compounds and oxides of nitrogen. The United Kingdom is committed through the United Nations (Economic Commission for Europe) Convention on Long Range Transboundary Air Pollution, and its Sofia and Geneva Protocols, to reducing emissions of oxides of nitrogen and volatile organic compounds. Studies of ozone formation and long range transport suggest that these international agreements should reduce peak hourly ozone concentrations by about 10 -20 ppb (10 -20%), and by about 10 -20 days per year with ozone concentrations greater than 50 ppb using an 8-hour running average, by the turn of the century. The Environment White Paper 'This Common Inheritance' points out that this international action, though welcome as a first step, will not solve our problems of ground level ozone formation and long range transport.
23. Furthermore, these studies of ozone formation and long range transport suggest that to prevent the occurrence of man-made episodes with an ozone 8-hour running average concentration greater than 50 ppb will require concerted action to reduce emissions of volatile organic compounds by about 75-85% or a greater than 95% reduction in oxides of nitrogen on current levels across Europe. Whilst such percentage reductions in emissions are technically feasible, they are beyond those contemplated in present policies. In order to monitor progress towards achievement of the Standard we recommend that ozone monitoring data in the United Kingdom are reported in terms of the number of days the Standard is exceeded at any one site per year.