Statistical models of CO concentration in a large urban area

Indications for the intervention strategies to be included in the context of air quality remediations plans for Milan metropolitan area obtained by evaluating 5 years of hourly CO concentration data. The work reports on the analysis of standard excesses and concentration time trends and on the development of empirical statistical models for describing relationships between annual concentration averages and air quality related parameters (number of standard exceedances, extreme percentiles of hourly concentration distributions). The models are applied, in combination with simple roll back equations, for the evaluation of emission reduction required for standards attainment. Similar statistical approaches for describing the dependence of the duration of excess episodes over fixed concentration levels with simple time series parameters (i.e. annual mean concentration) are also reported.