It can be seen that after a short period of high variations,the system equilibrates. The NO concentrations built up during the night and during the early-morning period,then it is replaced by NO2 and ozone is generated. By noon there are high concentrations of ozone and NO2. The trend for the ozone levels is decresing since the organic substances are consumed and other pollutants are formed (PAN and HNO3,for example).