Ground Level Ozone

Good vs. bad
Ozone is gas that is composed of three oxygen atoms. Good ozone is found in the Earth's upper atmosphere. Ozone found at that level is important because it protects us from harmful ultraviolet rays (UV rays) from the sun. Pollution is decreasing the amount of good ozone that is present in the atmosphere. Bad ozone is found near the ground and is usually referred to as ground-level ozone. Bad ozone contributes to smog and can be harmful at low levels.

Where does it come from?
Bad ozone is formed when sunlight hits gases. When the sunlight hits these gases they react to form ozone. The levels of bad ozone are usually higher in the summer but they can still be found at high level in urban areas during the winter. Ozone is easily carried by the wind and can travel many miles. This means that it can travel from large urban areas to the surrounding cities.

car exhaust

Emission sources
The gases that form ozone are nitrogen oxides (NOx) and volatile organic compounds (VOCs). These gases are formed in our everyday lives. They come from: 

  • Cars and trucks 
  • Power plants 
  • Factories 
  • Anything that burns fossil fuels 
  • Fires 
  • Waste disposal 
  • Breakdown of vegetation 
  • Break down of cleaning products  

Health effects
Ozone reacts with lung tissue, which can irritate the respiratory system. This can cause: 
  • Shortness of breath 
  • Coughing and sore or scratchy throat 
  • Difficulty breathing deeply 
  • Reduced lung function 
  • Inflamed or damaged cells that line the lungs 
  • Permanent lung damage 
  • Aggravate asthma and other chronic lung diseases 
  • Premature death from heart disease, strokes, and lung disease 

Who's at risk?
While bad ozone can be harmful to those with exposure, there are some groups that are at a higher risk:
  • Children are at the greatest risk because their lungs are still developing and they are usually more active outdoors when levels are high. 
  • Adults who are active outdoors have a higher risk because they can have a higher level of exposure from engaging in outdoor activities. 
  • People with respiratory disease have a higher risk because they are affected at lower levels. 
  • Older adults because they diseases that can be worsened by lower levels of exposure tend to be more prevalent within that age group.