Outdoor air quality can be affected by a wide variety of pollutants. Air pollutants come from many different sources and can be gaseous chemicals as well as tiny solid and liquid particles. The LDH Tracking Program presents air quality data on monitored ground level ozone and particulate matter (PM) that is less than 2.5 micrometers or smaller known as PM2.5. Ground level ozone and PM2.5 are believed to be the main cause of poor air quality in much of the country and have been linked to adverse respiratory and cardiovascular health effects.
Particle pollution, or particulate matter, consists of air borne particles like dust, dirt, soot, smoke and droplets of liquid. These particles come in a variety of sizes and shapes and can be made up of hundreds of different chemicals. Particle pollution includes coarse particles that are between 2.5 and 10 micrometers (PM10), fine particles that are between 0.1 micrometers and 2.5 micrometers (PM2.5), and ultrafine particles smaller than 0.1 micrometers. Particles bigger than 10 micrometers can irritate the eyes, nose and throat, but do not usually reach the lungs. Smaller particulates like PM2.5 can get deep into the lungs and even the bloodstream.
Ground Level Ozone is a gas that is created by chemical reactions between pollutants from cars, power plants, or other sources in presence of sunlight. Breathing ozone can result in a number of health effects especially for children, the elderly, and people with all ages who have respiratory diseases such as asthma.
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Tracking Outdoor Air Quality in Louisiana
The outdoor air quality data on the Health Data Explorer is sourced from the EPA Air Quality System, which obtains data for Louisiana from the Louisiana Department of Environmental Quality (LDEQ). For more information on Louisiana air quality, please refer to the LDEQ annual reports for the Ambient Air Monitoring Network.The Louisiana Ambient Air Monitoring Network consists of multiple air monitoring stations in Louisiana. Variation within parishes that do have monitors may exist, but are not captured in these measures. For parishes that have multiple monitors, the monitor with the highest reading on any day is used in the measure for the entire parish.
Air quality measures include the number of days and person-days during which the concentrations of ground level ozone and PM2.5 were higher than the National Ambient Air Quality Standards (NAAQS) established by the United States Environmental Protection Agency (EPA) under the authority of the Clean Air Act (42 U.S.C. 7401 et seq.). Person days are calculated as the number of days with air contaminant levels above the standard multiplied by the population of that parish. The highest number of person-days indicates areas with both a large exposed population and a large number of high pollution days.
Spatial gaps exist in the air quality monitoring network, especially in rural areas, since the air quality monitoring network is designed to focus on measurement of pollutant concentrations in high population density areas. The number of person-days may be more influenced by population than by contaminant levels considering the range in population from parish to parish is larger than the range in the number of high contaminant days. Also, some variability may result from environmental conditions. For example, the number of high ozone days is related to temperature, therefore there tends to be more high ozone days during the warmer summer months.
For a more detailed description of these measures, please see the Glossary of Terms.