To establish a typical pattern for the compn. of the atm. and the resulting dynamics, a large amt. of information concerning elementary chem. reactions, photochem., thermodn., catalysis, electrochem., spectroscopy, and quantum yields is necessary. A chemiluminescent method for detg. trace amts. of SO2 is described. The compn. of the lower atm. is largely dependent on the amts. of material discharged into the atm. on a local and regional basis. The formation of atm. aerosols (contg. primarily (NH4)2SO4) is due largely to the presence of SO2, resulting from industrial and domestic combustion of fuels. Photochem. smog is traceable primarily to the large amts. of NOx discharged into the atm. by motor vehicles which increases to a max. concn. of .apprx.100 ppb at the end of the day.