Eco-Pros
Environmental Education on the Web

Look in the distance for the results of Earth's smog test

EARTH WOULD NOT PASS THE SMOG TEST!

Smog is a mixture of noxious air pollutants, gases, and fine liquid and solid particles.  Urban smog (in densely populated areas/cities) contains harmful levels of ground-level ozone.  Ozone in our upper atmosphere (stratospheric ozone) is a useful gas ("good" ozone).  This ozone layer keeps much of the harmful UV radiation (ultra violet light) from reaching us at Earth's surface.  But, there is "good" ozone and "bad" ozone, depending upon where it is located.  Ozone concentrations at ground level (tropospheric ozone) are toxic and this "bad" ozone causes harm to living things.

Smog is most visible in very high concentrations. You can see the dense smog in the distance in the picture above of the 10-lane freeway clogged with fossil-fuel burning cars.  Millions of vehicles operate 24 hours a day, 7 days a week in large metropolitan areas, like Los Angeles for instance. If you look out the window of an airplane you can see the haze from smog that covers many regions below.  It mainly is concentrated in densely populated areas, but wind currents can carry it even hundreds of miles away and over other areas which had nothing to do with its origination. Smog can hover over areas for days if there are no winds to disperse it and help clean the air. Some of our national parks and ecologically important regions on our planet are being damaged from this human-caused pollution.  And respiratory ailments among adults and children have steadily increased over the years, with the elderly, sick and young children suffering the greatest harm to their health.

How is the ozone produced on Earth's surface?
Mix NOx and VOCs, apply sunlight and heat and you've got ozone.
Throw in some pollutants, water vapor and particulate matter and you've got smog.
Ozone is a product of chemical reactions between hydrocarbons and nitrogen oxides in the presence of sunlight.  It is created when oxides of nitrogen (NOx) and volatile organic compounds (VOCs) react in heat and sunlight.  NOx is produced and emitted by the burning of fossil fuels in vehicles, and in industrial and power plants. The main sources of VOCs come from industrial and commercial processes and motor vehicles.  VOCs are also released from paints, solvents, cleansers, aerosol sprays, dry-cleaned clothing, wood preservatives, automotive products and fuels. 

Layers of the Atmosphere Google has found about 536 images of the layers of the atmosphere.  If you have trouble finding them on this link, just type in "layers of the atmosphere" in Google's search box (without the quote marks)

Ozone Depletion  (EPA)

Is the Ozone Hole really a hole? What is ozone depletion?
(NASA's Global Change Master Directory Learning Center)

Ozone Hole and Ozone Depletion (Includes resource links at bottom of page)
When ultraviolet radiation from the sun reaches the ozone layer in the stratosphere, what happens?
Click on the globe for the TOMS sensor (Total Ozone Mapping Spectrometer). The TOMS instrument is used by NASA scientists to monitor the Antarctic ozone hole, and local and global ozone levels.  Take a look at the Aerosol Hot Spots page (wait for page load), and see how smoke and dust from desert dust storms, forest fires and biomass burning can be carried from one continent to another. (NASA's Global Change Master Directory)

The Ozone Hole Tour - University of Cambridge, UK

UV Index Information (National Weather Service Climate Prediction Center)
Learn all about ultraviolet radiation.