"Good" Ozone vs. "Bad" Ozone

  • You're probably familiar with the harmful effect on the ozone layer in the atmosphere from aerosols and other chemicals of modern life. The ozone that's up there "in the sky" is something we want to preserve, so you might think of it as "good" ozone.


    According to the United States Environmental Protection Agency (EPA), atmospheric ozone "occurs naturally in the stratosphere approximately 10 to 30 miles above the earth's surface and forms a layer that protects life on earth from the sun's harmful rays."


    However, there is another kind of ozone, called "ground-level ozone." You might think of it as the "bad" ozone. Ground-level ozone is found in the earth's lower atmosphere and is formed when motor vehicle exhaust, industrial emissions, gasoline vapors, chemical solvents and natural sources emit certain harmful substances into the air.

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    Then, sunlight and hot weather cause chemical reactions that force ground-level ozone into harmful concentrations. So, ground-level ozone is known as a summertime pollutant.


    As expected, urban areas often have ground-level ozone problems, but even rural areas may have high concentrations of this type of ozone. This is because wind currents can carry pollutants hundreds of miles away from their original sources.


    To learn more about ozone, you can visit the EPA website.


    Why Is Ground-Level Ozone Important to Asthmatics?


    So, you may be wondering why I'm posting about this topic. The reason is because ground-level ozone is not a good thing for anyone, but particularly for people who have asthma. Pollutants in the air can increase the risk of developing asthma. If you already have asthma, ground-level ozone can trigger your symptoms.


    The EPA sets air quality standards that industry and other entities are expected to abide by in the US. This is the reason for emission testing of automobiles and certain restrictions on manufacturing firms. And, since 1980, ozone levels in the USA have fallen by 21 percent, which is great.


    However, the air quality standards have not changed in 10 years, so the EPA is now saying they need to be tightened up even more to help preserve the clean air momentum moving into the future.


    Therefore, the EPA has proposed new standards. Here are the high points:

    • Stricter air quality standards - within the 0.070 to 0.075 parts per million (ppm) range 
    • A secondary standard aimed at improving protection for plants, trees and crops during the growing season
    • Public comments can be made for 90 days before the standards are signed into law
    • Public hearings scheduled for Los Angeles and Philadelphia on August 30 & Chicago and Houston on September 5th 

    If you are concerned about ground-level ozone and pollution, I encourage you to get involved!





Published On: June 26, 2007