Atmosphere and Air pollution• Structure of the

atmosphere• Human induced air

pollution• Major air pollutants:

primary and secondary• Health effects• Photochemical Smog• Acid Rain• Air pollution controls

Structure of the atmosphere

Human induced air pollution• London, 1952 major health

effects• Fires over Indonesia, Oct 22,

1997• Stationary: 1. Point sources: smokestack,

powerplant2. Fugitive sources: field

burning 3. Area sources: several

sources, farms sprayed with herbicides and pesticides

• Mobile Sources1. automobiles

Major Natural & man made pollutants

Primary: CO, VOC, NO’s, SOX, particulatessecondary pollutants: O3

Anthropogenic sources

Emissions

Secondary Pollutants: Photochemical Smog

Photochemical Smog in LA

Why LA?

Time course

Major air pollutants: primary and secondary

• Effects on people, plants, and materials

Health effects: cost and damage

Particulates

Plants

Acid Rain

• pH• Rainwater• Nitric acid• Sulfuric acid

Acid rain formation

Acid precipitation

Damage due to acid rain

Pollution Controls

Automobiles

• A three-way catalytic converter has three simultaneous tasks:• A. Reduction of nitrogen oxides to nitrogen and oxygen: 2NOx →

xO2 + N2 • B. Oxidation of (non greenhouse gas, but toxic) carbon monoxide to

less harmful (greenhouse gas) carbon dioxide: 2CO + O2 → 2CO2 • Oxidation of unburnt carcinogenic hydrocarbons (HC) to carbon

dioxide and water: 2CxHy + (2x+y/2)O2 → 2xCO2 + yH2O