AIR POLLUTION SOURCES 91
Part 1. Pollutant Emissions (continued)Pollutant types Sources and abundance Abatement and control
molecules and, thus, deplete the earth’s
protective ozone layer. This stratospheric
ozone depletion is a result of the photolytic
destruction of CFCs and, subsequent, release
of chlorine atoms in the middle stratosphere.
Chlorine and ozone react by the reactions:
Cl O 3 → ClO O 2 (10)
ClO O → Cl O 2 (11)
In these reactions, chlorine acts as a catalyst
since it is rapidly regenerated by reaction 11.
Estimates have shown that one chlorine atom
has the potential to destroy 100,000 ozone
molecules before the chlorine atom reacts
with hydrogen to form hydrochloric acid and
be removed from the cycle.
b. Fluorides: Fluorine is the 13th element in order of
abundance and exists in nature primarily as
fluorospar and fluorspatite which contain 49%
and 3–4% fluorine, respectively. Fluorospar is
the source of nearly all commercially used
fluorine. Fluorspatite is also known as
phosphate rock and is used in the manufacture
of phosphate fertilizers and elemental
phosphorous compounds comprising of
fluorine. It may occur in extremely low
concentrations in the atmosphere as solid
particles (sodium and calcium fluoride) or
highly irritating and toxic gases (hydrofluoric
acid). The processing of fluorospar and
fluorspatite are the predominate sources of
fluorine air pollutants. Industrial plants
manufacturing steel, glass, brick and tile, are
among the major emitters. The combustion of
coal is another source.Scrubbers, electrostatic precipitators or
baghouses can be used to remove particle
emissions while scrubbers can be used to
clean gaseous emissions. Most industrial
processes require the use of both.TABLE 12
Total National Emissions of Particulate Matter (PM-10), 1940 through 1994 (thousand short tons)
Source Category 1940 1950 1960 1970 1980 1990 1993 1994FUEL COMB. -ELEC. UTIL. 962 1,467 2,117 1,775 879 282 268 266
Coal 954 1,439 2,092 1,680 796 269 255 254
bituminous 573 865 1,288 1,041 483 187 184 182
FUEL COMB. -INDUSTRIAL 708 604 331 641 679 240 234 237
FUEL COMB. -OTHER 2,338 1,674 1,113 455 887 553 539 529
Commercial/Institutional Coal 235 224 21 13 8 14 13 13
Residential Wood 1,716 1,128 850 384 818 501 488 478
Residential Other 368 288 194 3 27 18 18 18
CHEMICAL and ALLIED PRODUCT MFG. 330 455 309 235 148 62 63 64
METALS PROCESSING 1,208 1,027 1,026 1,316 622 136 136 141
Nonferrous Metals Processing 588 346 375 593 130 45 45 46
copper 217 105 122 343 32 3 3 3
Ferrous Metals Processing 246 427 214 198 322 86 87 90
Metals Processing NEC 374 254 437 525 170 4 4 5
PETROLEUM and RELATED INDUSTRIES 366 412 689 286 138 28 27 26
Asphalt Manufacturing 364 389 639 217 97 4 4 4
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