Here's an environmental question worth asking: "Is ozone good or bad?" Need more context? All right. Has ozone benefited or harmed humans over the past century? Not sure? Well, read on and decide. If you are not motivated to do so, consider that if ozone were not part of the Earth, we would not be part of it either and, more immediately, if ozone levels are not maintained within some narrow ranges in the future, the biosphere will suffer greatly. What is ozone? Ozone is the gas in our atmosphere which has the chemical formula O3, which means that each of its molecules is made up of three oxygen atoms. Although seemingly similar to the much more common diatomic oxygen, O2, which we must consume with every breath, ozone is quite different. While our atmosphere is almost 21 percent O2, ozone is found in much smaller quantities, typically less than 1 part per million (that is, less than 0.0001 percent) . Additionally, although the concentration of O2 is equally distributed throughout the atmosphere (in terms of relative concentration), ozone has two distinct concentrations, that which resides near the surface (called tropospheric ozone) and that which resides in the upper atmosphere (above 10 miles in altitude, called stratospheric ozone). Ozone also has very different physical and chemical properties than O2. While most animals require O2 to survive, ozone is toxic and highly capable of destroying lungs, damaging the immune system, and reducing agricultural production. Ozone also creates potential problems because it is a greenhouse gas and, therefore, traps thermal energy in the Earth's atmosphere, meaning it can lead to "global warming." if levels become high. However, ozone is not always "bad", it is actually... middle of paper...... of these vehicles for positive action to be taken. In summary, ozone is a multidimensional gas. with its many influences on humanity and life in general. Some of its effects are considered essential while others are highly undesirable. Human-caused changes in ozone abundance, that is, lower amounts in the upper atmosphere and higher amounts in the lower atmosphere, have created more problems for us and other organisms of the planet. There are clearly things humans can and do do to alleviate these problems. Perhaps we can now begin to understand ozone as the vital (but dangerous) resource that it is. References: Goudie, Andrew. (2000) Human impact on the natural environment. Cambridge, MA: The MIT Press, 511 pp. Philander, S. George. (1998) Is temperature increasing. Princeton, New Jersey: Princeton University Press, 262 pages..