Sustainable Air Quality ME 449 Jan 14, 16; 2002

The Earth System Atmosphere –Conveyer of mass, moves mass source to receptor –Small storage capacity Hydrosphere –River system – conveyer collects substances in watershed –Oceans – long-term geochemical reservoir Lithosphere –Solid shell of inorganic matter at surface of the Earth made of up of soil particles and rock down to 50km –Within soil, biochemical reactions by microorganisms are responsible for most of the chemical changes of matter Biosphere –Thin shell of organic matter on the Earth’s surface (occupies the least volume) –Chemical pump for much of the flow of matter through nature –Responsible for grand scale recycling of energy and matter on the Earth

Source Types and Emissions Primary pollutants –Substances that are emitted directly into the atmosphere –E.g. VOCs, NO X, CO, particulate matter (PM) Secondary pollutants –Pollutants formed in the environment through chemical or photochemical transformations of primary pollutants –E.g. tropospheric ozone, PM Anthropogenic sources –Cars: NO X, VOCs, Pb, CO –Power plants: NO X, CO 2, CO, SO 2 –Agriculture: PM, NH 4 Natural sources –Wind blown dust: PM –Plants: VOCs –Volcanoes: SO 2, PM –Fires: smoke (PM), CO 2, Hg

Effects of Air Pollution Air pollution affects the following: –Human health (acute and chronic effects) –Animals –Plants –Materials –Visibility –climate

The activities of humans result in direct emissions of pollutants to the atmosphere Once airborne, these pollutants are transported, transformed, and concentrated The resulting pollutants may have negative effects on humans, plants, animals, and nature As a result of negative effects, laws and regulations are promulgated to either alter the activities or control their emissions with “end of the pipe” controls. Both of these strategies aim to reduce emissions.

Example: London Fog Population: London, a cold December week in 1957 Activity: home heating using soft, high-sulfur coal Emissions: SO 2 Transport: low wind speed – SO 2 is accumulated Chemical transformation: SO 2  SO 4 2-  acid aerosols (H 2 SO 4 ) Effect: 4000 deaths above normal (2.6% increase) Regulation: Reduce the use of soft coal Change Activity: fuel switching – change to hard coal, oil, gas, electricity

Air Quality Management Feedback System