Seasonal Variations

  • Variations in sunlight intensity cause variations in O3 production rate.
  • When the sun is most intense (i.e., Summer), O3 should reach highest levels, and primary pollutants should be at low concentrations.
  • In the winter, when the sun is weak, there will be reduced production of O3.
  • Primary pollutants, such as CO, reach seasonal maxima during the winter, but more from the lower mixing heights during this season than from the reduced sunlight intensity.  
  • The effect of low mixing heights would be to reduce the dispersion volume in which pollutants can mix, which increases the concentration if the source rate is the same.