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Air Quality Index. How Healthy is the Air You Breathe?. Air Pollution. Definition: The presence of one or more harmful chemicals in the atmosphere. Air Pollution. May cause harm to people, animals, vegetation, or materials, or may alter climate
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Air Quality Index • How Healthy is the Air You Breathe?
Air Pollution... • Definition: The presence of one or more harmful chemicals in the atmosphere
Air Pollution... • May cause harm to people, animals, vegetation, or materials, or may alter climate • Concentration (quantity) and duration are determinants of level of harm
How Does AirPollution Affect Us? • Humans breathe in 6-10 liters of air perminute • Harmful chemicals may be absorbed quickly without us being aware • Air pollutants come into contact first with our respiratory systems, so the lungs are most affected by this pollution • Air pollution may also affect the • Heart • Circulatory system • Immune system
Who Does AirPollution Affect? • The very young are at risk • Lungs are not fully developed until age 18 • They have a faster breathing rate • The very old are at risk • May have undiagnosed lung or heart disease • Pollution can exacerbate these conditions • Persons with chronic illnesses, especially those with respiratory, circulatory, or cardiac disease, are also at risk
Does Air Pollution Affect Anyone Else? • Yes,EVERYONE! • Even healthy persons can be affected when they exercise outdoors, or if the concentration of pollutants is very high
How Do We Know When the Air is Polluted and Unsafe? • Air pollution may be colorless or odorless, thus hard to detect • Air pollution may be obvious, as a brown or yellow haze, or with particulates in the air • By the time pollution is obvious, it may be at very unhealthy levels
What Causes Air Pollution? Nature • Air pollution may occur due to natural processes • This pollution is dispersed over a wide area, and is usually not as hazardous as other pollution
What Else CausesAir Pollution? • People! Air pollution may also occur due to human activities • Called ‘anthropogenic’ sources • Stationary sources, such as power plants or industry • Mobile sources, such as vehicles
Because it is Sometimes Difficult to Know... • To protect public health, the Environmental Protection Agency (EPA) monitors 5 air pollutants in what is called the ‘Air Quality Index’ (AQI) • Ground-level Ozone (O₃) • Particulate Matter (Particle Pollution) • < 2.5 microns • < 10 microns • Carbon Monoxide (CO) • Sulfur Dioxide (SO₂) • Nitrogen Dioxide (NO₂)
How Values to Calculate AQI are Generated • Monitors record the average concentration for each of the air pollutants • The time recorded varies by pollutant • In some circumstances, models are used to determine values for AQI
How AQI is Calculated • An equation is used with the pollution concentration data and an AQI break-point table • See http://www.epa.gov/airnow/aqi_tech_assistance.pdf for details • AQI is calculated for each pollutant • The pollutant with the highest AQI determines the level for the day, and is noted as the responsible pollutant
AQI Values • AQI values range from 0-500 • The higher the AQI, the greater the air pollution and health concerns • An AQI of 100 corresponds to the national air quality standard for that pollutant • A value <100 is generally considered satisfactory and not a health hazard • A value >100 indicates air quality may be unhealthy for some groups • A value >300 represents very hazardous air quality
What are CommonAQI Levels? • AQI levels are generally 0-100 in most U.S. communities • AQI >100 may occur only a few times of year, if at all • Some U.S. metropolitan areas have greater pollution and thus AQIs >100 • AQIs >200 are rare in the U.S. • In other countries with dense population areas, uncontrolled sources of pollution, and fewer governmental emission restrictions, AQIs are frequently >250
AQI Categories • AQI values are converted to a category for easier understanding by the public • Categories consider the public health impacts of the pollution level • A color code is used to associate the actions to be taken at that level
AQI Reporting • Metropolitan Statistical Areas (MSAs) with populations >350,000 are required by Federal law to report the AQI daily to the general public
AQI Distribution • AQI may be distributed: • To media • Newspapers • Radio • Television • Provided as a recorded telephone message • Published on an Internet site that is accessible to the public
The AQI Report • Provides data on current day’s air quality and may include the next’s day’s air quality forecast • MUST include: • Reporting area • Reporting period • Critical pollutant • AQI
The AQI ReportMUST Also Include... • Information on specific health concerns for certain populations • Descriptor must be used:“Good” through “Hazardous” • Color Code must be noted:“Green” through “Maroon” • Cautions for sensitive groups for any pollutants with an AQI over 100
Action Days • ‘Action Days’ are called when the AQI is in the unhealthy range. • Individual agencies/cities determine at what level to call ‘Action Days’ • Some use ‘Unhealthy for Sensitive Groups’ or Code Orange • Sensitive groups should avoid prolonged or heavy outdoor exertion outdoors • Other cities use ‘Unhealthy’ or Code Red • People should avoid prolonged or heavy outdoor exertion outdoors
Other Preventative Actions • High levels of AQI may trigger various restrictions or prohibitions by local governments to protect the public health • Officials consider: • Current pollutant concentrations • Prevailing weather conditions • Forecasted weather conditions
Possible High AQI Actions • Levels above 200 may cause an “Alert” stage • Activities restricted mayinclude incinerator use oropen burning of leaves orrefuse
Possible High AQI Actions • Levels above 200 may cause an “Alert” stage • Activities restricted may include incinerator use or open burning of leaves or refuse • Levels above 300 may trigger a “Warning” stage • Incinerator use may be prohibited, power plant operations cut back, specific manufacturing operations curtailed, and public driving limited with public transportation and carpooling encouraged
AQI Emergency Actions • Levels above 400 would be an “Emergency” • Would require most industrial and commercial activity to cease, and almost all private vehicle use to cease • Death would occur in some very sensitive individuals • Sensitive individuals might be hospitalized • Healthy persons would probably experience symptoms that would restrict normal activities
Seasonal Variations in AQI • Winter • CO may be highest level pollutant • Vehicle emission control systems do not operate as well in cold weather • Levels are generally highest during morning or evening rush hours • Summer • VOCs and NOx form ozone more rapidly in the presence of heat and sunlight • Levels peak in the afternoon
Smog/Ozone ‘Season’ • Smog/Ozone ‘Season’ is generally May to September • March 1- October 31 in Georgia • Ozone may not be reported in other months unless the level is high or the ‘season’ is longer for that area
Ozone Standards • EPA strengthened air quality standards for ground-level ozone in March, 2008 • Ground-level ozone is a primary component of smog • Lower levels of ozone are now reported as unhealthy in AQI and daily smog forecasts
Particle Pollution Maps • Available year-round for some cities • Some state and local agencies are not yet participating in this program
EPA Proposal for Stronger NO₂ Air Quality Standards • 06/29/2009 Proposal to update standards to reflect newest findings of NO₂ exposure on public health • Propose to monitor NO₂ levels for a shorter time period • Recent research indicates that short-term exposure to high NO₂ levels, ranging from 30 minutes to 24 hours, may increase respiratory problems, especially in persons with asthma, children, or the elderly. • Propose to monitor within 50 meters of major roadways in cities with at least 350,000 residents • Often a higher concentration of NO₂ near major roadways than at monitoring stations • Proposal decision on new standard required by Jan. 22, 2010
Other Considerations • AQI levels are not the only factors in determining how healthy the air is in a place- other factors include: • Transportation patterns • Industrial composition • Location of monitoring sites • Weather patterns, such as inversions
One Last Consideration... • Synergism of pollutants has not been fully studied • Combinations of pollutants may increase harmful effects • Combinations of pollutants may cause harmful effects to occur at lower levels • Combinations of pollutants may cause new or currently unknown problems • EPA will likely modify the AQI as more research is available in this area
Air Quality Index (AQI) Summary • The AQI is: • Used to protect public health • Used to determine appropriate activities for people, industry, and commerce • Calculated from monitored values of 5 major pollutants • An effective tool to determine how well Clean Air Act standards are being met by our communities