PHOTOCHEMICAL lSMOG

Mon 12/34/56 4:00

PHOTOCHEMICAL SMOG

Photochemical smog - brown smog - is a mix of primary and secondary pollutants and Volatile Organic Compounds (VOC) that reacts with sunlight and heat.

Fossil fuel combustion related:

N2 + O2 = 2NO → 2NO + O2 = 2NO2 (nitrogen dioxide)

3NO2 + H2O =2HNO3 + NO (nitric acid)

UV Radiation

NO2 + UV radiation NO + O–––>O2 + O = O3 (photochemical ozone)

Chemical Reactions resulting in Photochemical Smog

Hydrocarbons + O2 + NO PANs (peroxyacyl nitrates)

O & O3 + Hydrocarbons aldehydes

INVERSION LAYERS

Blankets of air trapping various sorts of air pollutants. Natural ventilation by the convection mechanism is not possible.

URBAN HEAT ISLAND

BROWN CLOUD

THE IMPORTANCE OF ATMOSPHERIC CONVECTION

MORTALITY

Air pollution is one of the major environ-mental causes of premature mortality.