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Air Quality and Your Health

Air pollution is linked to a number of health problems such as asthma, heart disease and breathing problems among others. National air quality has improved over the last 20 years. However, many challenges still exist in protecting public health and the environment from air quality problems. Since the 1950s, air quality has been a major public health and environmental issue.  Local, state and national programs all have provided considerable information on the health problems caused by poor air quality and how to solve them.
The Environmental Public Health Tracking (EPHT) network at CDC is closely aligned with the national Environmental Protection Agency (EPA) to be able to provide air quality data on the CDC Health Tracking Network.  This collaboration provides data and information to better understand how air pollution affects public health. On the CDC Health Tracking Network, information is available regarding air quality and health.  PA EPHT also reports information on air quality on its website. On this page of the PA EPHT website you will find data and information about a broad range of air pollutants and the kinds of problems these can cause.
The Clean Air Act 
The Clean Air Act requires EPA to set National Ambient Air Quality Standards for six common air pollutants. These commonly found air pollutants, also known as criteria pollutants, are found throughout the United States.  They are particle pollution (often referred to as particulate matter), ground-level ozone, carbon monoxide, sulfur oxides, nitrogen oxides and lead. These pollutants can harm both health and the environment.  Of the six pollutants, ground-level ozone and particle pollution are the most widespread health threats. These two pollutants are what appear on the PA EPHT website.  EPA calls all six pollutants criteria air pollutants because it regulates them by developing human health-based and environmentally-based criteria, or science-based guidelines, for setting permissible levels.
EPA's Criteria Pollutants for Air:
       1.OZONE - Ground level or bad ozone is not emitted directly into the air, but is created by
          chemical reactions between chemical oxides of nitrogen and volatile organic compounds
          (VOCs) in the presence of sunlight.  Emissions from industrial facilities and electric utilities,
          motor vehicle exhaust, gasoline vapors and chemical solvents are just some of the major
          sources of nitrogen oxides and VOCs. Breathing ozone can trigger a variety of health problems
          particularly for children, the elderly and people who have lung diseases such as asthma.   
          Ground-level ozone can also have harmful effects on sensitive vegetation and the
 2. PARTICULATE MATTER - Particulate matter, also known as particle pollution or PM, is a complex mixture of extremely small particles and liquid droplets.  Particle pollution is made up of a number of components, including acids, organic chemicals, metals, and soil or dust particles.  The size of particles is directly linked to their potential for causing health problems.  EPA is particularly concerned about particles that are 10 micrometers or less in diameter since these are the particles that generally pass through the throat and nose and enter the lungs.  Once inhaled, these particles can affect the heart and lungs and cause serious health effects. EPA further groups particle pollution into two categories:         
            - Inhalable coarse particles, such as those found near roadways and dusty industries, are
         larger than 2.5 micrometers and smaller than 10 micrometers in diameter. 
       - Fine particles, such as those found in smoke and haze, are 2.5 micrometers in diameter 
         and smaller.  These particles can be directly emitted from sources such as forest fires, or
         they can form when gases emitted from power plants, industries and automobiles react 
         in the air.
3. CARBON MONOXIDE - Carbon monoxide CO is a colorless, odorless gas emitted from combustion processes.  Nationally the majority of CO emissions to air come from mobile souces. CO can cause harmful health effects by reducing oxygen delivery to the body's organs, like the heart and brain, and tissues.  At extremely high levels, CO can cause death.
4.  NITROGEN OXIDES - Nitrogen dioxide NO2 is one of a group of highly reactive gasses known
          as  oxides of nitrogen, or nitrogen oxides. Other nitrogen oxides include nitrous acid and nitric
          acid. NO2 forms quickly from emissions from cars, trucks and buses, power plants and off-road
          equipment. In addition to contributing to the formation of ground-level ozone, and fine particle
          pollution, NO2 is linked with a number of adverse effects on the respiratory system. EPA first set
          standards for NO2 in 1971.  The agency has reviewed the standards twice since that time, but
          chose not to revise the annual standards at the conclusion of each review.  In January 2010,
          EPA established an additional primary standard at 100 parts per billion averaged over one hour.
          Together the primary standards protect public health including the health of sensitive populations
          - people with asthma, children and the elderly.  No area of the country has been found to be out
          of compliance with the current NO2 standards.
     5.  SULFUR DIOXIDE - Sulfur dioxide SO2 is one of a group of highly reactive gasses known as
          oxides of sulfur.  The largest sources of SO2 emissions are from fossil fuel combustion at
          power plants and other industrial facilities.  Smaller sources of SO2 emissions include industrial
          processes such as extracting metal from ore, and the burning of high sulfur containing fuels by
          locomotives, large ships and non-road equipment.  SO2 is linked with a number of adverse
          effects on the respiratory system.
     6.  LEAD - Lead Pb is a metal found naturally in the environment as well as in manufactured
          products.  The major sources of lead emissions have historically been from fuels in motor
          vehicles, such as cars and trucks, and industrial sources. Today, the highest levels of lead in
          air are usually found near lead smelters.  The major sources of lead emissions to the air today
          are ore and metals processing and piston-engine aircraft operating on leaded aviation
Tracking Air Quality
EPA provides their air quality data to the CDC database for its tracking network.  In the future, CDC’s Tracking program will combine additional health and air quality data to produce more understandable indicators of the health impacts of air pollution. These indicators do more than show the concentrations of air pollutants and the number of people living in areas that exceed standards. These new indicators could estimate outcomes like the number of hospital admissions or deaths associated with those concentrations.
CDC’s tracking program also is working with EPA to produce air quality indicators in areas where there are no air monitors. This is done by combining air monitoring data with emissions and meteorological data to create daily estimates of ozone and airborne fine particulates. This will help produce a more complete picture of air pollution across the country.
Ambient Air Quality Monitoring in the United States:
Monitoring Networks
Federal, state and local air agencies operate and maintain a wide variety of air monitoring systems across the United States.  Many of these systems serve multiple environmental objectives.  At a basic level, they let us know how clean or polluted the air is and help us track progress in reducing air pollution.  They also inform the public about air quality in their communities through the Air Quality Index.  EPA provides guidance to help these groups understand the quality of the data produced by these networks. The data from these monitors are used to characterize the status of the nation's air quality and the trends across the United States.
Air Quality System Database
EPA’s Air Quality System (AQS) database contains ambient air pollution data. The data are collected by EPA, state, local and tribal air pollution control agencies. There are thousands of monitoring stations across the United States.  AQS also contains meteorological data, information about each monitoring station such as its location and its operator, and data quality assurance and quality control information.  State and local agencies are required to submit their air quality monitoring data into AQS.  This ensures timely submission of these data for use by state, local and tribal agencies, EPA and the public.
The Air Quality System is important because it helps EPA and others to: 
       -  Assess air quality
       -  Assist in determining which areas of the country are meeting air quality standards
       -  Evaluate state plans for controlling air pollution
       -  Perform modeling for permit review analysis
       -  Perform other air quality analyses such as trend analysis and health effect studies
AQS information is also used to prepare reports for Congress, which is required by the Clean Air Act.
Air quality data are required to assess public health impacts caused by poor air quality, determine whether an area is meeting the standards, and evaluate changes in air quality as a result of state implementation plans.  The challenge is to get measurements of air quality in time and space that are useful for Environmental Public Health Tracking activities.
To compare and correlate ambient concentrations with acute health effects, daily local air quality data is needed.  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.
PM 2.5 monitors generally collect samples once every three days, due in part to the time and costs involved in collecting and analyzing the samples. However, monitors that can automatically collect, analyze and report PM 2.5 measurements on an hourly basis have been introduced over the past several years.  These monitors are available in most major metropolitan areas.  Ozone is monitored daily, but mostly during the ozone season (the warmer months, primarily April through October).  Year-long data would be extremely useful to evaluate whether ozone is a factor in health outcomes during the non-ozone seasons.

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