We have found earlier that air components of photochemical origin vary with the 11-year periodicity, and concentrations of ozone and aerosol lag behind the solar activity by 2-3 years. To find the reasons for this phenomenon, we have analyzed the ozone mechanism, as well as consequences of variations in the UV radiation influx. The analysis revealed some intermediate mechanism, which is likely caused by the interaction of the increasing UV irradiation with plants. At the beginning of UV irradiation increase, some inhibition of plant's growth is noticed. After 1-2-year adaptation period, some increase in plant's productivity appears leading to extra emissions of ozone- and aerosol-forming substances into the atmosphere. This hypothesis was checked using the normalized vegetation index and gave good results. Based on the regularities revealed, we make a prognosis of variations of the ozone and aerosol concentrations from 2003 to 2008.