Air Pollution

Indoor/Outdoor

The Atmosphere Troposphere

Stratosphere

78% N, 21% O

Ozone layer

Greenhouse effect

Outdoor Air Pollution•airborne particles and gasses•concentrations that endanger:o heath and well-being of organisms o disrupt the orderly functioning of the environment

(1) primary pollutants: emitted directly from identifiable sources, and (2) secondary pollutants: produced in the atmosphere when certain chemical reactions take place among primary pollutants.

Secondary Pollutants• Atmospheric sulfuric acid is one example of a secondary

pollutant. • Air pollution in urban and industrial areas is often called

smog. • Photochemical smog, a noxious mixture of gases and

particles, is produced when strong sunlight triggers photochemical reactions in the atmosphere.

• The major component of photochemical smog is ozone.

Photochemical Smog

Brown-air smog

Photochemicalreaction

Photochemicaloxidants

Regional Outdoor Air Pollution from Acid Deposition

Acid deposition

Wet deposition Dry deposition

Acid Deposition in the US

Acid Deposition and Humans Respiratory diseases Toxic metal leaching Decreased visibility Damage to structures, especially

containing limestone Decreased productivity and

profitability of fisheries, forests, and farms

Acid Deposition and Aquatic Systems

Fish declines

Undesirable species

Aluminum toxicity

Acid shock

Acid Deposition, Plants, and Soil Nutrient

leaching

Heavy metal release

Weakens trees

Zoom In

Indoor Air Pollution/Sick Building Syndrome

Radon Radon-222 Occurs in certain

areas based on geology

Associated with uranium and organic material in rock

2nd most common cause of lung cancer

Air Pollution Occurrences• quantity of contaminants emitted into the

atmosphere• changes in certain atmospheric conditions

– (1) the strength of the wind and – (2) the stability of the air.

Air Mixing• Wind speed affects concentration of pollutants• Atmospheric stability determines extent to which vertical

motions mix pollution with cleaner air above the surface layers

• Mixing depth: vertical distance between Earth's surface and the height to which convectional movements extend

• Greater the mixing depth, the better the air quality• Air temp differences lead to differences in air density

Inversions• Temperature inversions: atmosphere very stable and the

mixing depth significantly restricted • Diffusion is inhibited and high pollution concentrations are to

be expected in areas where pollution sources exist

Inversion

This is an example of a generalized temperature profile for a surface inversion.

Temperature-profile changes in bottom diagram after the sun has heated the surface.

Controlling Air Pollution through Regulations

• Economic activity, population growth, meteorological conditions, and regulatory efforts to control emissions, all influence the trends in air pollution.

• The Clean Air Act of 1970 mandated the setting of standards for four of the primary pollutants—– particulates, – sulfur dioxide, – carbon monoxide, and – Nitrogen– as well as the secondary pollutant ozone.

Emission Reduction

Key Terminology“Natural” air pollution Primary pollutantsSecondary pollutants SmogPhotochemical smog OzoneClean Air Act (1970) Acid PrecipitationMixing depth InversionSurface inversion