Air Quality Index
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Good
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Air quality is considered satisfactory, and air pollution poses little or no risk.
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Moderate
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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.
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Unhealthy for Sensitive Groups
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Although general public is not likely to be affected at this AQI range, people with lung disease, older adults and children are at a greater risk from exposure to ozone, whereas persons with heart and lung disease, older adults and children are at greater risk from the presence of particles in the air.
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Unhealthy
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Everyone may begin to experience some adverse health effects, and members of the sensitive groups may experience more serious effects.
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Very Unhealthy
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This would trigger a health alert signifying that everyone may experience more serious health effects.
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Hazardous
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This would trigger a health warnings of emergency conditions. The entire population is more likely to be affected.
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PM2.5
Fine particles (PM2.5) are 2.5 micrometers in diameter or smaller, and can only be seen with an electron microscope. Fine particles are produced from all types of combustion, including motor vehicles, power plants, residential wood burning, forest fires, agricultural burning, and some industrial processes.
PM10
Coarse dust particles (PM10) are 2.5 to 10 micrometers in diameter. Sources include crushing or grinding operations and dust stirred up by vehicles on roads.
Ozone (tropospheric)
Ozone (O3) is a constituent of the troposphere. The troposphere extends from the Earth's surface to between 12 and 20 kilometers above sea level and consists of many layers. At abnormally high concentrations brought about by human activities (largely incomplete combustion of fossil fuels, such as gasoline, diesel, etc.), it is a pollutant, and a constituent of smog. Many highly energetic reactions produce it, ranging from combustion to photocopying. Often laser printers will have a smell of ozone, which in high concentrations is toxic. Ozone is a powerful oxidizing agent readily reacting with other chemical compounds to make many possibly toxic oxides. Health effects depend on ozone precursors, which is a group of pollutants, primarily generated during the combustion of fossil fuels. Reaction with daylight ultraviolet (UV) rays and these precursors create ground-level ozone pollution. (Source:Wikipedia)
Sulfur dioxide (SO2)
Current scientific evidence links short-term exposures to SO2, ranging from 5 minutes to 24 hours, with an array of adverse respiratory effects including bronchoconstriction and increased asthma symptoms. These effects are particularly important for asthmatics at elevated ventilation rates (e.g., while exercising or playing.) Studies also show a connection between short-term exposure and increased visits to emergency departments and hospital admissions for respiratory illnesses, particularly in at-risk populations including children, the elderly, and asthmatics. (Source:EPA)
Nitrogen dioxide (NO2)
Current scientific evidence links short-term NO2 exposures, ranging from 30 minutes to 24 hours, with adverse respiratory effects including airway inflammation in healthy people and increased respiratory symptoms in people with asthma. Also, studies show a connection between breathing elevated short-term NO2 concentrations, and increased visits to emergency departments and hospital admissions for respiratory issues, especially asthma. (Source:EPA)
