AIR POLLUTION EVSC1300 Prof. Stephan De Wekker

air pollutants: harmful airborne substances that, when present in high enough concentrations, threaten human health or welfare, harm vegetation, animals or structures or affect visibility.

Air pollution disasters London's Killer Fog of 5-9 December 1952 Burning of sulphur-bearing fuels under poor dispersion conditions with fog or high humidity. 4-5 days. Anticyclone. May have killed 4,000 people Donora, Pennsylvania, valley fog of 26 October 1948 steel mill, zinc smelter, sulfuric acid plant 17 people died in 14 hours (22 total)

Primary pollutants - pollutants emitted directly into atmosphere. Carbon monoxide, Lead, Oxides of sulfur (sulfur dioxide and sulfur trioxide), Oxides of nitrogen (nitric oxide and nitrogen dioxide), Hydrocarbons (volatile organic compounds, or VOCs); Particulates PM-2.5: particulate matter < 2.5 micrometers PM-10: particulate matter <10 micrometers Secondary pollutants - pollutants produced in the atmosphere as a result of chemical or physical transformations of primary pollutants Present harder-to-solve problems than primary air pollutants Include acid deposition and photochemical oxidants (smog)/ozone Natural pollutants - pollutants produced naturally (not by man) Anthropogenic pollutants (human-caused)

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Figure 02: CO in lower troposphere – satellite image Courtesy of NASA

Primary Pollutants Primary Pollutant Sources United States Pollutants and Sources

Approaches to reduce pollution For example: Clean Air Act of 1970, last amended in 1990 National Ambient Air Quality Standards Emissions restrictions

U.S. Emission Estimates

Also see: criteria.html

Non-attainment Areas (2003) CO, SO 2, NO 2, O 3, PM

Los Angeles Air Pollution

Trends in Air Pollutant Concentrations in the United States from 1990 to 2007

Non-attainment Areas (as of March, 2012)

What meteorological factors affect air pollution concentration?

Wind strength effect Whiteman (2000)

Plume dispersion Whiteman (2000) Mixing depth concept Temperature inversion, Plume rise

Mixing Layer

Early morning Late morning Afternoon Early evening Night

Urban Heat Island

Synoptic regime effect Whiteman (2000)