Health and Environmental Effects of Particulate Matter
United States Environmental Protection Agency
Office of Air & Radiation
Office of Air Quality Planning & Standards
July 17, 1997
HEALTH AND ENVIRONMENTAL EFFECTS OF PARTICULATE MATTER
Why are We Concerned About Particulate Matter?
Who is Most at Risk from Exposure to Fine Particles?
- Particulate matter is the term used for a mixture of solid
particles and liquid droplets found in the air. Coarse particles
(larger than 2.5 micrometers) come from a variety of sources
including windblown dust and grinding operations. Fine particles
(less than 2.5 micrometers) often come from fuel combustion, power
plants, and diesel buses and trucks.
- These fine particles are so small that several thousand of them
could fit on the period at the end of this sentence.
- They are of health concern because they easily reach the
deepest recesses of the lungs.
- Batteries of scientific studies have linked particulate matter,
especially fine particles (alone or in combination with other air
pollutants), with a series of significant health problems,
- Premature death;
- Respiratory related hospital admissions and
emergency room visits;
- Aggravated asthma;
- Acute respiratory
symptoms, including aggravated coughing and difficult or
- Chronic bronchitis;
- Decreased lung function
that can be experienced as shortness of breath; and
- Work and school absences.
How do Particulate Matter and Fine Particles Affect the Environment?
- The Elderly:
- Studies estimate that tens of thousands of elderly people die
prematurely each year from exposure to ambient levels of fine
- Studies also indicate that exposure to fine particles is
associated with thousands of hospital admissions each year.
Many of these hospital admissions are elderly people suffering
from lung or heart disease.
- Individuals with Preexisting Heart or Lung Disease:
- Breathing fine particles can also adversely affect individuals
with heart disease, emphysema, and chronic bronchitis by
causing additional medical treatment. Inhaling fine
particulate matter has been attributed to increased hospital
admissions, emergency room visits and premature death among
- The average adult breathes 13,000 liters of air per day;
children breathe 50 percent more air per pound of body weight
- Because children's respiratory systems are still developing,
they are more susceptible to environmental threats than
- Exposure to fine particles is associated with increased
frequency of childhood illnesses, which are of concern both in
the short run, and for the future development of healthy lungs
in the affected children.
- Fine particles are also associated with increased respiratory
symptoms and reduced lung function in children, including
symptoms such as aggravated coughing and difficulty or pain in
breathing. These can result in school absences and
limitations in normal childhood activities.
- Asthmatics and Asthmatic Children:
- More and more people are being diagnosed with asthma every
year. Fourteen Americans die every day from asthma, a rate
three times greater than just 20 years ago. Children make up
25 percent of the population, but comprise 40 percent of all
- Breathing fine particles, alone or in combination with other
pollutants, can aggravate asthma, causing greater use of
medication and resulting in more medical treatment and
What Improvements Would Result from EPA's New Standards?
- The same fine particles linked to serious health effects are also a
major cause of visibility impairment in many parts of the U.S.
- In many parts of the U.S. the visual range has been reduced 70%
from natural conditions. In the east, the current range is only
14-24 miles vs. a natural visibility of 90 miles. In the west, the
current range is 33-90 miles vs. a natural visibility of 140 miles.
- Fine particles can remain suspended in the air and travel long
distances. For example, a puff of exhaust from a diesel truck in
Los Angeles can end up over the Grand Canyon, where one-third of
the haze comes from Southern California. Emissions from a Los
Angeles oil refinery can form particles that in a few days will
affect visibility in the Rocky Mountain National Park. Twenty
percent of the problem on dirtiest days in that Park is attributed
to Los Angeles-generated smog.
- Airborne particles can also cause soiling and damage to materials.
Background: What is Particulate Matter and What are "Fine" Particles?
- EPA's new standards will provide increased health protection from
the following effects:
- About 15,000 lives each year will be saved, especially among
the elderly and those with existing heart and lung diseases.
- Reduced risk of hospital admissions by thousands each year,
and fewer emergency room visits, especially in the elderly and
those with existing heart and lung diseases.
- Reduced risk of symptoms associated with chronic bronchitis,
tens of thousands fewer cases each year.
- Reduced risk of respiratory symptoms in children, hundreds of
thousands fewer incidences each year of symptoms such as
aggravated coughing and difficult or painful breathing.
- Reduced risk of aggravation of asthma, hundreds of thousands
fewer incidences each year, in children and adults with
- Reduced risks of susceptibility to childhood illnesses.
- Improved visibility over broad regions in the east and urban areas:
- The Clean Air Act placed special emphasis on preserving
visibility in certain national parks and wilderness areas. In
response, EPA is developing a "regional haze" program intended
to ensure all parts of the country make continued progress
toward the national visibility goal of "no manmade
- New standards that EPA has promulgated, together with the
"regional haze" program under development, will protect
against visibility impairment, soiling and material damage
effects, and will further reduce acid rain.
- Particulate matter originates from a variety of sources, including
diesel trucks, power plants, wood stoves and industrial processes.
The chemical and physical composition of these various particles
vary widely. While individual particles cannot be seen with the
naked eye, collectively they can appear as black soot, dust clouds,
or grey hazes.
- Those particles that are less than 2.5 micrometers in diameter are
known as "fine" particles; those larger than 2.5 micrometers are
known as "coarse" particles. Fine particles result from fuel
combustion (from motor vehicles, power generation, industrial
facilities), residential fireplaces and wood stoves. Fine
particles can be formed in the atmosphere from gases such as sulfur
dioxide, nitrogen oxides, and volatile organic compounds. Coarse
particles are generally emitted from sources such as vehicles
traveling on unpaved roads, materials handling, and crushing and
grinding operations, and windblown dust.
- EPA is also maintaining a national air quality standard focused on
small particles less than 10 micrometers in diameter (known as
"PM10") to protect against coarse particle effects. Ten micrometers
are about one-seventh the diameter of a human hair.
- Before 1987, EPA's standards regulated larger particles (so called
"total suspended particulates"), including those larger than 10
micrometers. By 1987, research had shown that the particles of
greatest health concern were those equal to or less than 10
micrometers that can penetrate into sensitive regions of the
respiratory tract. At that time EPA and states took action to
monitor and regulate particulate matter 10 micrometers and smaller.
- In the years since the previous standard was enacted, hundreds of
significant new scientific studies have been published on the
health effects of particulate matter. Recent health effects studies
suggest those adverse public health effects, such as premature
deaths and increased morbidity in children and other sensitive
populations, have been associated with exposure to particle levels
well below those allowed by the current standard.