[Patterns of variations for air concentrations of some pollutants]

Patterns of diurnal variations for the air concentration of some pollutants emitted from motorvehicles are presented. Primary pollutants (carbon monoxide, nitric oxide and reactive hydrocarbons) and secondary pollutants (ozone and nitrogen dioxide) are continuously monitored since 1974. Different typical patterns have been obtained in the winter and in the summer season. The values of r for 14 regression curves calculated for couples of primary pollutants are in the range from 0.73 to 0.95, indicating their common source. Diurnal patterns obtained for summer and winter are discussed in the light of photochemical atmospheric processes Values for the ratio NO/NO2 are higher than 1 in the winter season; the same ratio is lower than 1 in summer, from 13 to 24 hours.