Air Quality
Guide for Particle Pollution
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Key Facts You Should Know About Particle
Pollution
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What are particles? Where do they come from?
Particles in the air are a mixture of solids and liquid droplets that vary in size and are often referred to as "particulate matter." Some particles - those less than 10 micrometers in diameter - pose the greatest health concern because they can pass through the nose and throat and get deep into the lungs. Ten micrometers in diameter is just a fraction of the diameter of a single human hair. Particles larger than 10 micrometers do not usually reach your lungs, but they can irritate your eyes, nose and throat. Very small particles with diameters less than 2.5 micrometers are called "fine particles." They are produced any time fuels such as coal, oil, diesel or wood are burned. Fine particles come from fuel used in everything from power plants to wood stoves and motor vehicles (e.g., cars, trucks, buses and marine engines). These particles are even produced by construction equipment, agricultural burning and forest fires. "Coarse" dust particles range in size from 2.5 to 10 micrometers in diameter. Particles of this size are produced during crushing or grinding and from vehicles traveling on paved or unpaved roads. How can particle pollution affect you? Fine and coarse particles can cause a variety of serious health problems. When exposed to these particles, people with heart or lung diseases and older adults are more at risk of hospital and emergency room visits or, in some cases, even death. These effects have been associated with short-term exposures lasting 24 hours or less. Long-term exposures of a year or more have been linked to the development of lung diseases, such as chronic bronchitis. Particles can aggravate heart diseases such as congestive heart failure and coronary artery disease. If you have heart disease, particles may cause you to experience chest pain, palpitations, shortness of breath and fatigue. Particles have also been associated with cardiac arrhythmias and heart attacks. Particles can aggravate lung diseases such as asthma and bronchitis, causing increased medication use and doctor visits. If you have lung disease, and you are exposed to particles, you may not be able to breathe as deeply or vigorously as normal. You may have respiratory symptoms including coughing, phlegm, chest discomfort, wheezing and shortness of breath. You also may experience these symptoms even if you're healthy, although you are unlikely to experience more serious effects. Particles can also increase your susceptibility to respiratory infections. How can you reduce your exposure to particles? Air pollution levels can vary throughout the day. Your local air quality forecast can tell you when particle levels are high in your area. You can reduce your exposure to particles by 1) planning strenuous activity when particle levels are forecast to be lower, 2) reducing the amount of time spent at vigorous activity, or 3) choosing a less strenuous activity (e.g., going for a walk instead of a jog). When particle levels are high outdoors, they also can be high indoors. Certain filters and room air cleaners are available that can help reduce particles indoors. You also can reduce particles indoors by eliminating tobacco smoke and reducing your use of candles, wood-burning stoves and fireplaces. For more information on indoor air pollution and filter devices, visit ww |
Particle Pollution (PM10) and (PM2.5)
Particle pollution (also known as "particulate
matter") in the air includes a mixture of solids and liquid droplets. Some
particles are emitted directly; others are formed in the atmosphere when other
pollutants react. Particles come in a wide range of sizes. Those less than 10
micrometers in diameter (PM10) are so small that they can get into the lungs,
potentially causing serious health problems. Ten micrometers is smaller than
the width of a single human hair.
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Fine particles
(PM2.5). Particles less than 2.5 micrometers
in diameter are called "fine" particles. These particles are so small
they can be detected only with an electron microscope. Sources of fine
particles include all types of combustion, including motor vehicles, power plants, residential wood burning, forest fires, agricultural burning,
and some industrial processes.
Coarse dust particles. Particles between 2.5 and 10 micrometers in diameter are referred
to as "coarse." Sources of coarse particles include crushing or
grinding operations, and dust stirred up by vehicles traveling on roads. Carbon
monoxide, or CO,is a colorless, odorless gas that is formed when carbon in
fuel is not burned completely. It is a
component of motor vehicle exhaust, which contributes about 56 percent of all
CO emissions nationwide. Other non-road
engines and vehicles (such as construction equipment and boats) contribute
about 22 percent of all CO emissions nationwide. Higher levels of CO generally occur in areas
with heavy traffic congestion. In cities,
85 to 95 percent of all CO emissions may come from motor vehicle exhaust. Other sources of CO emissions include
industrial processes (such as metals processing and chemical manufacturing),
residential wood burning, and natural sources such as forest fires. Woodstoves, gas stoves, cigarette smoke, and
unvented gas and kerosene space heaters are sources of CO indoors. The highest levels of CO in the outside air
typically occur during the colder months of the year when inversion conditions
are more frequent. The air pollution
becomes trapped near the ground beneath a layer of warm air.
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CO. . .
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is poisonous even to healthy people
at high levels in the air.
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can affect people with heart disease.
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can affect the central nervous
system.
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Nitrogen dioxide
(NO2) is one of a group of highly reactive gasses known as
"oxides of nitrogen," or "nitrogen oxides (NOx)." Other nitrogen oxides include nitrous acid
and nitric acid. While EPA’s National Ambient Air Quality Standard covers this
entire group of NOx, NO2 is the component of greatest interest and
the indicator for the larger group of nitrogen oxides. 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, setting both a primary standard (to protect health) and a secondary standard (to protect the public welfare) at 0.053 parts per million (53 ppb), averaged annually. The Agency has reviewed the standards twice since that time, but chose not to revise the standards at the conclusion of each review. All areas in the U.S. meet the current (1971) NO2 standards.
Sulfur dioxide, or SO2, belongs to the family of sulfur oxide gases (SOx). These gases dissolve easily in water. Sulfur is prevalent in all raw materials, including crude oil, coal, and ore that contains common metals like aluminum, copper, zinc, lead, and iron. SOx gases are formed when fuel containing sulfur, such as coal and oil, is burned, and when gasoline is extracted from oil, or metals are extracted from ore. SO2 dissolves in water vapor to form acid, and interacts with other gases and particles in the air to form sulfates and other products that can be harmful to people and their environment. Sulfur Dioxide
Health and Environmental Impacts of SO2
EPA first set standards for NO2 in 1971, setting both a primary standard (to protect health) and a secondary standard (to protect the public welfare) at 0.053 parts per million (53 ppb), averaged annually. The Agency has reviewed the standards twice since that time, but chose not to revise the standards at the conclusion of each review. All areas in the U.S. meet the current (1971) NO2 standards.
Sulfur dioxide, or SO2, belongs to the family of sulfur oxide gases (SOx). These gases dissolve easily in water. Sulfur is prevalent in all raw materials, including crude oil, coal, and ore that contains common metals like aluminum, copper, zinc, lead, and iron. SOx gases are formed when fuel containing sulfur, such as coal and oil, is burned, and when gasoline is extracted from oil, or metals are extracted from ore. SO2 dissolves in water vapor to form acid, and interacts with other gases and particles in the air to form sulfates and other products that can be harmful to people and their environment. Sulfur Dioxide
Health and Environmental Impacts of SO2
SO2
causes a wide variety of health and environmental impacts because of the way it
reacts with other substances in the air.
Particularly sensitive groups include people with asthma who are active
outdoors and children, the elderly, and people with heart or lung disease.
Respiratory Effects from Gaseous SO2 - Peak levels of SO2 in the air can cause temporary
breathing difficulty for people with asthma who are active outdoors. Longer-term exposures to high levels of SO2
gas and particles cause respiratory illness and aggravate existing heart
disease.
Respiratory Effects from Sulfate Particles - SO2 reacts with other chemicals in the air to form tiny sulfate particles. When these are breathed, they gather in the lungs and are associated with increased respiratory symptoms and disease, difficulty in breathing, and premature death.
Respiratory Effects from Sulfate Particles - SO2 reacts with other chemicals in the air to form tiny sulfate particles. When these are breathed, they gather in the lungs and are associated with increased respiratory symptoms and disease, difficulty in breathing, and premature death.
Visibility Impairment - Haze occurs when light is scattered or absorbed by
particles and gases in the air. Sulfate
particles are the major cause of reduced visibility in many parts of the U.S., including
our national parks.
Acid Rain - SO2 and nitrogen oxides react with other substances in the air
to form acids, which fall to earth as rain, fog, snow, or dry particles. Some may be carried by the wind for hundreds
of miles.
Plant and Water Damage - Acid rain damages forests and crops, changes the makeup
of soil, and makes lakes and streams acidic and unsuitable for fish. Continued exposure over a long time changes
the natural variety of plants and animals in an ecosystem.
Aesthetic Damage - SO2 accelerates the decay of building materials and
paints, including irreplaceable monuments, statues, and sculptures that are
part of our nation's cultural heritage.
You Can Help Keep the Air Cleaner!
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Air Quality Index (AQI) - A Guide to
Air Quality and Your Health
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. EPA
calculates the AQI for five major air pollutants regulated by the Clean Air Act:
ground-level ozone, particle pollution (also known as particulate matter),
carbon monoxide, sulfur dioxide, and nitrogen dioxide. For each of these
pollutants, EPA has established national air quality standards to protect
public health.Ground-level ozone and airborne particles are the two
pollutants that pose the greatest threat to human health in this country.
How Does the AQI Work?
Think of the AQI as a yardstick that runs from 0 to 500. The
higher the AQI value, the greater the level of air pollution and the greater
the health concern. For example, an AQI value of 50 represents good air
quality with little potential to affect public health, while an AQI value
over 300 represents hazardous air quality.
An AQI value of 100 generally corresponds to the national air
quality standard for the pollutant, which is the level EPA has set to protect
public health. AQI values below 100 are generally thought of as satisfactory.
When AQI values are above 100, air quality is considered to be unhealthy-at
first for certain sensitive groups of people, then for everyone as AQI values
get higher.
Understanding the AQI
The purpose of the AQI is to help you understand what local air
quality means to your health. To make it easier to understand, the AQI is
divided into six categories:
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Air
Quality Index
Levels of Health Concern |
Numerical
Value |
Meaning
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Good
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0-50
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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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51-100
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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 who are
unusually sensitive to air pollution.
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Unhealthy for
Sensitive Groups |
101-150
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Members of sensitive groups may experience health effects. The
general public is not likely to be affected.
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Unhealthy
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151-200
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Everyone may begin to experience health effects; members of
sensitive groups may experience more serious health effects.
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Very Unhealthy
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201-300
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Health alert: everyone may experience more serious health
effects.
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Hazardous
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> 300
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Health warnings of emergency conditions. The entire population
is more likely to be affected.
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