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VOCs
are emitted from a wide variety of sources, including: automobiles and other vehicles (also called "mobile sources"); refineries and chemical manufacturing plants ("major stationary
sources"); paint shops and dry cleaners ("minor" or "area sources"); recreational boats, ships, barges, lawn and garden equipment, aircraft, and locomotives ("off-road mobile sources"); and
even plants and trees ("biogenics"). Nitrogen oxide comes from some of the same sources -- automobiles, boats, trains and planes, and refineries -- as well as from service stations, home heating and cooling units, wastewater treatment plants, power plants, and forest fires. The TCEQ has estimated both the amount and the sources of VOCs and nitrogen oxides released into the atmosphere in major Texas metropolitan areas, with sources differing significantly depending upon the area.
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NITROGEN OXIDES AND VOLATILE ORGANIC COMPOUND EMISSIONS
IN TEXAS'S MAJOR METROPOLITAN AREAS
|
|
METROPOLITAN AREA
|
POLLUTANT
|
TOTAL
(TONS PER DAY)
|
SOURCES BY PERCENT
|
|
MAJOR
INDUSTRIAL
|
MINOR
INDUSTRIAL
|
MOBILE
ON-ROAD
|
MOBILE
OFF-ROAD
|
|
Houston / Galveston / Brazoria
|
NOX
|
975.39
|
49.4%
|
20.5%
|
16.8%
|
13%
|
|
VOC
|
1331
|
58.7%
|
1%
|
25.3%
|
15%
|
|
Dallas / Ft. Worth
|
NOX
|
548.83
|
11.9%
|
31.7%
|
37.2%
|
19.1%
|
|
VOC
|
596
|
18.3%
|
3.4%
|
49.2%
|
29.4%
|
|
Beaumont / Port Arthur
|
NOX
|
313.53
|
78.3%
|
9.8%
|
6.1%
|
5.8%
|
|
VOC
|
297
|
74.4%
|
0.3%
|
13.8%
|
11.1%
|
|
San Antonio
|
NOX
|
271
|
36%
|
21%
|
41%
|
2%
|
|
VOC
|
228
|
2%
|
34%
|
42%
|
22%
|
|
Longview / Marshall / Tyler
|
NOX
|
264
|
74%
|
1%
|
18%
|
7%
|
|
VOC
|
138
|
31%
|
26%
|
21%
|
22%
|
|
Corpus Christi
|
NOX
|
161
|
62%
|
1%
|
23%
|
14%
|
|
VOC
|
144
|
41%
|
20%
|
18%
|
21%
|
|
Austin
|
NOX
|
141
|
14%
|
3%
|
56%
|
27%
|
|
VOC
|
159
|
1%
|
31%
|
45%
|
23%
|
|
El Paso
|
NOX
|
69.4
|
13.6%
|
35.9%
|
34.6%
|
15.8%
|
|
VOC
|
88
|
37.5%
|
2.3%
|
42%
|
17%
|
|
Source: Texas Natural Resources Conservation Commission, Revisions to the State Implementation Plan for Ozone (1996).
|
|
Note: El Paso represents a special case. The table shows only sources from
within the El Paso County area, where an estimated 69.4 tons of NOx and 88 tons of VOCs are released into the atmosphere - a relatively low amount compared to
Texas's other cities. However, El Paso shares the border with Ciudad Juárez, Mexico, which has a significant influence on air quality in Mexico.
Stationary/Area Sources:
Major industrial sources (petroleum storage and petrochemical facilities, major manufacturing plants, gasoline pipelines, power plants) and area minor industrial sources (gasoline stations, dry cleaners, oil and gas production, small coating and painting operations, small print shops, landfills, wastewater treatment facilities, consumer commercial solvent use).
Mobile Sources:
Off-road (recreational boats, agricultural, construction, industrial equipment, lawn and garden equipment, airplanes) and on-road (highway vehicles, both gasoline and diesel).
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