Total Suspended Particulates
particles or aerosols that are less than 100 micrometers are
collectively referred to as total suspended particulate matter
(TSP). These particles constantly enter the atmosphere from many
Human sources include:
- Motor vehicle use.
- Combustion products from space
- Industrial processes.
- Power generation.
Natural sources include:
- Bacteria and viruses.
- Fungi, molds and yeast.
- Salt particles from evaporating
Over 99% of
inhaled particulate matter is either exhaled or trapped in the upper
areas of the respiratory system and expelled. The balance enter the
windpipe and lungs, where some particulates, known as inhalable
particulates, cling to protective mucous and are removed. Other
mechanisms, such as coughing, also filter out or remove particles.
Collectively, these "pulmonary clearance" mechanisms protect the
lungs from the majority of inhalable particles.
Some of the smallest particles,
called respirable particulates, lodge in the lung capillaries and
alveoli, causing the following effects:
- Slowing down the exchange of
oxygen and carbon dioxide in the blood, causing shortness of
- Straining the heart, because it
must work harder to compensate for oxygen loss.
The people most sensitive to these
conditions include those with heart problems, or respiratory
diseases like emphysema, bronchitis and asthma. The elderly and
children are also very sensitive.
The adverse health effects from
particulate matter exposure are often not immediately noticed.
Particulates can accumulate in the lungs after repeated, long-term
exposure causing respiratory distress and other health problems.
Some particles themselves may be
poisonous if inhaled or absorbed, and can damage remote organs like
the kidneys or liver. Swallowed mucous laden with poisonous
particulate matter may also damage the gastrointestinal system.
Irritating odors are often associated
with particulates. Some examples of sources are gasoline and diesel
engine exhausts, large-scale coffee roasting, paint spraying, street
paving and trash burning.
U.S. EPA replaced TSP as the
indicator for both the annual and 24-hour primary (i.e.,
health-related) standards in 1987. The indicator includes only those
particles with an aerodynamic diameter smaller than or equal to a
nominal ten micrometers (PM10 - Particulate Matter 10
microns or less). Exposure to PM10 particles, which are
retained deep in the lungs, may cause health problems. The specific
health effects PM10 causes are discussed below.
Damage and Other Effects
matter is what most people see and feel when they experience "dirty
air." Particulate matter can:
- Corrode metals and masonry.
- Soil structures and motor
vehicles. (Cleaning, e.g., window washing, sand blasting, and
repainting, costs millions of dollars annually.)
- Dust the leaf surfaces of crops,
trees and shrubs, which may injure or inhibit the growth of these
- Impair visibility and reduce solar
radiation. (Very small particles remain suspended in the air for
long periods of time, and also effectively scatter light. The haze
caused by these particles can affect crop productivity by reducing
solar radiation; it can also adversely affect property values;
aesthetics in urban, country-side and wilderness areas;
transportation safety; and potentially the weather.)