Ozone pollution, a key component of smog, is the most widespread air quality problem in the United States. Harmful ozone is not emitted directly into the air. Instead, it is formed in sunlight, which initiates a series of complex atmospheric chemical reactions. These reactions primarily involve two main precursors: nitrogen oxide (NOx) and volatile organic compound (VOC) emissions.

Nitrogen oxide emissions are almost entirely produced as a by-product of high-temperature combustion in cars, trucks, boats, construction equipment, power generators, industrial processes, and natural gas furnaces.

Volatile organic compounds include many organic chemicals that vaporize easily, such as those found in gasoline and industrial solvents. In addition, biogenic, or natural, emissions from trees and plants are another major source of VOCs.

The concentration of ozone in the air is determined not only by the amounts of ozone precursor chemicals, but also by weather and climate factors. Intense sunlight, warm temperatures, stagnant high-pressure weather systems and low winds cause ozone to accumulate in harmful amounts during the summer months in North Central Texas.

Poor air quality can damage the environment and property. Plants and animals and their habitats can be harmed by air pollution. Air pollution has thinned the protective “good” ozone layer above Earth. It can damage buildings, monuments, statues, and other structures. Air pollution can also result in haze, which reduces visibility and can sometimes interfere with aviation.

In addition to its impacts to the environment and to the economy, poor air quality can also cause health problems, including burning eyes and nose, itchy irritated throat, headaches, nausea, coughing or wheezing, and difficulty breathing. Research has shown that some contaminants found in polluted air can cause cancer, birth defects, brain and nerve damage, and long-term injury to the lungs and breathing passages. Above certain concentrations and durations, air pollutants can be extremely dangerous and can lead to severe injury or death. Doctors and scientists acknowledge heavy correlations between poor air quality and respiratory illnesses.

Pay close attention to local media to determine how clean or how hazardous the air quality is in your area on any given day.  The media will use a system developed by the Environmental Protection Agency (EPA) called the Air Quality Index (AQI).  The AQI is an index for reporting daily air quality. It tells you how clean or polluted your air is, and what associated health effects might be a concern for you. The AQI focuses on health effects you may experience within a few hours or days after breathing polluted air.  The following is a chart and description of the AQI.   

Each category corresponds to a different level of health concern. The six levels of health concern and what they mean are:

• "Good" The AQI value for your community is between 0 and 50. Air quality is considered satisfactory, and air pollution poses little or no risk.
  
  
• "Moderate" The AQI for your community is between 51 and 100. Air quality is acceptable; however, for some pollutants there may be a moderate health concern for a very small number of people. For example, people who are unusually sensitive to ozone may experience respiratory symptoms.
  
  
• "Unhealthy for Sensitive Groups" When AQI values are between 101 and 150, members of sensitive groups may experience health effects. This means they are likely to be affected at lower levels than the general public. For example, people with lung disease are at greater risk from exposure to ozone, while people with either lung disease or heart disease are at greater risk from exposure to particle pollution. The general public is not likely to be affected when the AQI is in this range.
  
  
• "Unhealthy" Everyone may begin to experience health effects when AQI values are between 151 and 200. Members of sensitive groups may experience more serious health effects.
  
  
• "Very Unhealthy" AQI values between 201 and 300 trigger a health alert, meaning everyone may experience more serious health effects.
  
  
• "Hazardous" AQI values over 300 trigger health warnings of emergency conditions. The entire population is more likely to be affected.

If the AQI is high for your area, take steps to limit your exposure to harmful atmosphere.  This includes staying indoors during peak hours of the day and limiting high physical activity while you are outside.  Consult your physician immediately if you begin to feel ill or if you are showing any of the symptoms outlined above.

In addition, we can all do our part to limit the amount of pollutants that are released into the atmosphere.  Please visit the EPA website and AIRNow.gov for more information on AQI, harmful pollutants, and steps we can take to reduce poor air quality.

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