Modeling of Ozone and Hydrogen Peroxide in Air

Ozone (O3) and hydrogen peroxide (H2O2) volume fractions were calculated using the Master Mechanism (MM) model, author S. Madronich (NCAR, Boulder, CO, USA). MM is an atmospheric “box” model program for calculating the time evolution of atmospheric composition from initial amounts of atmospheric gases under chosen or varying conditions using reaction rate data and other physicochemical parameters. The photolysis coefficients were calculated using the Tropospheric Ultraviolet Visible (TUV) program of the same author. Data gathered during the field measurements in 2004 and modeled with the MM program are used here to determine how gradual increase of one initial value of the following eight quantities: NO2, CO, VOC (i.e. some volatile organic compounds), BTX (i.e. benzene, toluene, xylenes), H2O2, O3, temperature and relative humidity, will in the MM modeling affect the volume fractions of either ozone or hydrogen peroxide. According to the model, H2O2 volume fractions in air increase with higher relative humidity and higher initial values of CO, VOC, BTX, H2O2 and O3, and only decrease by NO2. On the other hand, ozone volume fractions do rise with the increase of initial volume fractions of NO2, as well as of CO, VOC, BTX, H2O2 and O3. Temperature does not have any significant influence on the formation of H2O2 and O3. The results also may explain the considerably higher ozone values measured at the airport than in the city of Zagreb.