94 AIR POLLUTION SOURCES
Part 1. Pollutant Emissions (continued)Pollutant types Sources and abundance Abatement and controlbetween 10 and 15 million people in the United
States are affected by seasonal allergic (hay-fever).a) Ragweed—has been found in all 50 states, it
produces large quantities of pollen, and the
grains are especially adapted for aerial
dissemination by virtue of their size (20 m),
shape, and density. It has been estimated that
an acre of giant ragweed may produce as much
as 50 lbs of pollen during a single season.
b) Fungi—(molds) usually habitating in soil and
dust, can become a menace when airborne.
Their concentration in the air is dependent
upon the magnitude of the source, their death
rate in the air, humidity, temperature and
other factors.
c) Danders—(small particulate organic
materials), including feathers of fowl and hair
of animals and house dust.
2) Man-made sources:
a) Flour mills—grain dusts produced in flour-
milling plants (have been identified as a
cause of asthma).
b) Castor bean dust-oil processing plants. Most
sources of biological aerosols are natural.Herbicide (p lant killers)—are
sometimes used, but they are not
only to ragweed, but to all plants.
For eradicating molds, a number of
disinfectants have been utilized.
Man-made sources are subject to
normal particulate control methods
as well as good housekeeping
practices in plants.- Asbestos: General name given to a variety of fibrous
minerals found in rock masses. The value of asbestos
ensues from the indestructible nature of products
fabricated from the various grades of mineral fibers.
The major asbestos minerals are: (Pyroxenes)
chrysolite (amphiboles—), crocidolite, amosite, and
anthophyllite. Tremolite and actinolite are
considerably less important. Over 90% of the
asbestos is chrysolite.
Major sources are:
a) Asbestos mines and factories.
b) The wearing of brake linings, roofing
insulation and shingles.
c) Fireproofing of buildings with sprayed
asbestos applications.
d) Road surfacing.
e) Asbestos cement.
f ) Asbestos removal.a) IN MANUFACTURING:
Ventilation through fabric sleeve
filters carrying out some operations
(such as spinning and weaving of
asbestos fabrics) as wet processes to
eliminate dust.
b) IN TRANSPORTATION:
Use of plastic-coated bags to
transport asbestos.
c) IN CONSTRUCTION REMOVAL:
Use of insulators to enclose the work
area when asbestos fire-proofing is
blown onto steel frames. Wetting of
asbestos prior to removal.- Non metallic elements:
a. BORON: A non-metallic chemical element which
occurs only in combination with other elements as with
sodium and other elements (as with sodium and oxygen
in borax). Most important pollutants are boron dust and
borane fuel. The borones are the most highly toxic of
the boron compounds, consists chiefly of pentaborane,
decaborane, and diborane.
Major sources are: Rocket motor or jet engines
which use borane, a compound of boron, for
a high energy fuel; combination of petroleum
fuels which contain boron as an additive;
burning of coal containing boron;
manufacturing processes employed to
produced boron compounds which are used
as wastes softness.
Natural abundance: Boron is widely distributed
in nature, but constitutes only an estimated in
0.001% of the earth’s crust. It is present in
sea water, and is an essential constituent of a
number of rock-forming silicate minerals,
such as datolite and tourmaline. Boron occurs
naturally only in combined forms, usually as
air alkaline earth borate or as boric acid.
The compounds known to be emitted in
appreciable quantities into the ambient air are
phosphorus oxides, phosphoric acid, mostly in
agricultural chemicals. Other organic
phosphorus compounds are very probably
emitted into the ambient air by the chemical
industry from processes in which phosphorous
products are intermediate or final outputs.1) Prevention of accidental spilling of
fuels.
2) Reduction or elimination of boron
additives in vehicle fuels.b. PHOSPHORUS: A solid non-metallic element
existing in at least two allotropic forms, one yellow
(poisonous, inflammable, and luminous in the dark),
the other red (less poisonous, and less inflammable).
Elemental phosphorus (yellow) is a protoplasmic
poison. Some of its compounds, especially organic
phosphates, can also be lethal to man and animal in
the case of exposure to high air concentrations.Major control methods: Scrubbers
cyclones, fiber mist eliminators,
high energy wire-mesh contactors
and electrostatic precipitators are
used in the control of phosphorus
emissions.C001_006_r03.indd 94C001_006_r03.indd 94 11/23/2005 9:42:40 AM11/23/2005 9: