Before implementing the second European directive, the member states of the European Union should assess the air quality for carbon monoxide and benzene in their countries.
Checks against the limit values show no exceedances in the Netherlands in 2000. The concentrations of benzene and carbon monoxide show a downward trend. A further decrease in both components is expected. If the air quality is only determined on the basis of measurements, a total of 15 measurement stations will be compulsory in the Netherlands for measuring carbon monoxide and 19 for benzene. The requirement for carbon monoxide can be met if the current LML stations are classified differently. For benzene, the current configuration is not sufficient. As the concentrations are expected to decrease further, the choice here has been for a combination of new monitors with additional instruments to assess the air quality.