An overview of sources of air pollution

Air pollution comes from a variety of sources, many of which we see in our everday lives but do not recognize as sources of pollution.  The following is an overview of point and non-point sources, and specific examples of both.  It may be suprising to see that air pollution comes from every level of our society.

Point Sources

"Industrial and nonindustrial stationary equipment or processes considered significant sources of air pollution emissions. A facility is considered to have significant emissions if it emits about one ton or more in a calendar year." (Texas Commission on Environmental Quality)

• industrial and commercial boilers
• wood and pulp processors
• petroleum storage tanks
• piping leaks
• industrial wastewater treatment ponds
• rock and quarry operations

Non-Point Sources

The first thing that comes to mind when non-point sources are discussed is usually cars.  While cars, or on-road mobile sources, are a significant source of emissions, it is only one of four non-point emissions sources.  The other three are: non-road mobile sources (planes, boats, lawn mowers), biogenic (non-human) sources, and area sources.

1. On-road Mobile sources

The vehicles in this category are cars and other gasoline vehicles, diesel vehicles, and motorcycles.

2. Non-Road Mobile Sources

These non-road mobile sources are often overlooked, but contribute significant amounts of air pollution, mostly in the form of VOCs, nitrogen oxides, and carbon dioxide.  Two major emissions sources among these are lawn mowers and recreational boats.

• Aircraft
  • Commercial
  • Military
• General
  • Locomotives
  • Ships and barges
• Small Engines
  • Lawn and garden
  • • * lawn mower
    • chain saw
    • snowblower
    • string trimmer
  • Airport support vehicles
    
    • terminal tractor
  • Recreational vehicles
    • ATV
    • mini bike
    • golf cart
    • snowmobile
  • Recreational marine
    • * small vessels
    • sailboats with auxiliary engines
  • Light commercial
    
    • generators
    • welders
    • air compressors
  • Industrial construction
    
    • forklift
    • sweeper/scrubber
  • Construction
    • paving equipment
    • signal boards
    • cement and mortar mixers
    • cranes
    • graders
    • off-highway trucks
    • crushing/process equipment
    • tractors/loaders/backhoes
  • Agricultural
    • 2-wheel tractors
    • Combines
    • Sprayers
    • Balers
  • Logging
    • Chainsaws
    • Shredders
    • Fellers/bunchers

3. Biogenic Emissions

Biogenic, or natural (non-human), emissions account for 30 percent of all the volatile organic compounds (VOCs) emitted in urban areas in the eastern half of Texas.  The majority is the VOC isoprene, a byproduct of photosynthesis, which is released from the many trees in the Gulf Coast and Piney Woods regions ot Texas.  Isoprene readily reacts to form ozone.  VOCs are harmful because they react to form ozone.

4. Area Sources

Area source emissions are similar to point source emissions, but generally release emissions in smaller quanitities.  Major categories of areas source emissions are:

• Stationary source fuel combustion
  • Coal
  • Natural Gas
  • Wood
• Solvent use
  • Barge, tank, rail car, drum cleaning
  • Consumer and commercial solvent use
  • Dry cleaning
  • Graphic arts (spray paint)
  • Asphalt
• Product storage and transport distribution
  • Aircraft and vehicle refueling
  • Leaking underground tanks
  • Catastrophic/accidental releases
• Light industrial/commercial sources
  • Bakeries
  • Breweries
  • Wineries
• Agriculture (e.g., feedlots, crop burning)
  • Pesticide application
  • Orchard heaters
  • Prescribed burning and forest fires
• Waste management (e.g., landfills)
  • Landfills
  • Wastewater treatment
• Painting operations
  • Auto refinishing
  • Traffic markings
  • Electrical insulation
  • Other product coatings
• Miscellaneous area sources (e.g., wind erosion, unpaved roads)

Source:
"Sources of Air Pollution." Texas Commission on Environmental Quality. 2008. TCEQ. 6 Feb. 2009 <http://www.tceq.state.tx.us/implementation/air/areasource/Sources_of_Air_Pollution.html#Biogenic>.