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Human Impact on the Atmosphere


    1.    Discuss how human activities can affect the atmosphere.

    2.    Compare and contrast acid rain, smog, and global warming.

Key Terms:

    air pollution        temperature inversion

Notes: (17-4)

As an industrialized nation we are constantly forced to weigh the effects of manufacturing versus the benefits of the products.  Pollution is a term given to a harmful (gas or particulate) substance that is released into the environment.  Although some pollution occurs naturally (volcanoes) most pollutants are produced as a result of industry.

There are several different classifications:

  1. irritant - causing inflammation and discomfort
  2. teratogen - causing birth defects
  3. carcinogen - causing cancers

Proliferation of of pollutants depletes our ozone layer, contributes to increased global warming, increases the amount of acid rain, and puts people at risk for health problems.  In 1970 the Clean Air Act sought to address 6 of the worst known pollutants.  The EPA (Environmental Protection Agency) monitors these pollutants and sets acceptable levels for their release.

  1. CO - Carbon monoxide
  2. NO2 - Nitrogen dioxide
  3. SO2 - Sulfur dioxide
  4. Particulate pollutant
  5. Pb - lead
  6. O3 - ozone


(www.tanplusforhealth.com/Images/ Ess%20Air/Pollutants.gif)



Acid Rain

Acid rain is created as CO2, NO2 and SO2 mix with water in the atmosphere to create weak acids that return to the Earth's surface as rain.  This rain accumulates in the water table and in the fresh water systems where it becomes concentrated killing wildlife, vegetation, and bacteria.



Smog is a term used to describe a collection of pollution that is condensed in a particular area.

generally a brownish color
mostly formed from the burning of fossil fuels
rich in NO2, SO2 and CO2
creates surface ozone
creates a temperature inversion (top layer warmer than the lower layer) which aids in the trapping of more smog at increasingly lower levels

picture of smoggy city

(www.epa.gov/airnow/health/ images/smog.jpg)

Ozone Concentration (ppm)
(8-hour average, unless noted)
Air Quality Index
Air Quality
0.0 to 0.064 0 to 50 Good
0.065 to 0.084 51 to 100 Moderate
0.085 to 0.104 101 to 150 Unhealthy for
Sensitive Groups
0.105 to 0.124 151 to 200 Unhealthy
0.125 (8-hr.) to 0.404 (1-hr.) 201 to 300 Very Unhealthy


Ozone Depletion

Ozone depletion is perhaps the most overlooked environmental hazard.  Although the banning of CFCs in the 1970s helped slow the thinning of this layer, the depletion continues today.  Effects of thinning are:

increased skin cancers
premature aging
plant damage
reduction in the amount of phytoplankton in the oceans

ozone hole illustration


(www.epa.gov/grtlakes/seahome/ thumbs/ozone.jpg)



Global Warming

Although global warming is vital to the survival of the planet, its rate of increase threatens life.  Most scientists will conclude that global warming is a natural process that has cycles of increase and decrease but there are undeniable contributions that we are making that have significantly sped up the process of warming.

Burning of fossil fuels - releases CO2
Global deforestation - increases CO2 levels

These activities have led to the the following consequences:

Rising sea levels
Increased frequency of damaging storms - hurricanes and tornados
Increased frequency of severe weather - heat waves and droughts
Relocation of global crop growing areas








Last modified: December 09, 2003