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The Six Criteria Air Pollutants

  • (See endnote 28)
  • 1. Carbon monoxide

Carbon monoxide is typically produced by the burning of hydrocarbon fuels. People are exposed to the pollutant: by inhaling indoor and outdoor air from a combination of residential, mobile (vehicular traffic, the most frequent source), and heavy industry (refineries, power plants using gas and coal, chemical plants, coke oven plants, etc.) sources; heavy equipment, farming equipment, and residential heating; and through the processing and storage of a variety of hydrocarbons, as well as in the occupational setting. Carbon monoxide may cause chest pain, headaches, aggravate heart disease, and result in emergency measures performed at a hospital. It can and does cause death.

Best Practices for Carbon Monoxide

  • • Utilize a program of motor vehicle inspection to determine if there is proper combustion of fuel.
  • • Avoid cold and rapid starts of motor vehicles to reduce levels of carbon monoxide.
  • • Utilize a program of motor vehicle maintenance to get maximum combustion of fuel in a proper manner.
  • • Do not operate gasoline power tools and engines in confined spaces.
  • • Establish programs of timely examinations of firefighters and other emergency response people and provide effective medical care when needed.
  • • Establish a program for the proper use and maintenance of fireplaces and wood burning heaters to make sure that there is appropriate combustion of the fuel.
  • • Enforce no smoking rules in public facilities to reduce the level of carbon monoxide inhaled by people.
  • • Substitute less hazardous paint strippers and other chemicals for more hazardous compounds.
  • • Publicize areas of high carbon monoxide potential to young families to try to encourage them to live in areas other than those related to industry and high traffic.
  • • Develop programs to more efficiently use fuel as a means of reducing carbon monoxide and other contaminants.
  • • Use continuous emission monitoring systems to record and report carbon monoxide from stationary sources.
  • 2. Ozone—Ground-Level

Ozone (ground-level), a major component of smog, is typically formed when there is a chemical reaction in the atmosphere between a VOC and nitrogen oxides in the presence of sunlight. The VOCs may come from the burning of fuel, cars burning gasoline, chemical manufacturing plants, and petroleum refineries, as well as the use and storage of solvents, petroleum, and other hydrocarbons, as well as landfills. Inhalation leads to difficulty in breathing and lung tissue damage. Children are especially at risk because they play and exercise during the summer out- of-doors when the ozone levels are at their highest. Ozone may also damage rubber, some plastics, forests, and agricultural crops. The weather and topography is especially a problem if the person is in a depressed area such as a valley or in a city at street level between tall buildings. This type of configuration contributes to the concentration of ground-level ozone. The number of vehicles present adds substantially to the problems. (See endnote 8.)

Best Practices for Ozone—Ground-Level

  • • Reduce nitrogen oxide emissions from power plants and industrial combustion sources.
  • • Introduce low emission cars and trucks, use cleaner gasoline, and increase the efficiency of gasoline to get more mileage per gallon burned.
  • • Where feasible use solar, nuclear, hydroelectric, and wind power in place of fossil fuels.
  • • Reduce use of automobiles by carpooling, mass transit, and making less frequent trips for small things.
  • • Use low evaporation VOC solvents and paints in place of high evaporation VOC solvents and paints.
  • • Recover vapor during refueling of automobiles at service stations.
  • • Inspect all automobiles on an annual basis for emissions of hydrocarbons, nitrogen oxides, sulfur oxides, and carbon monoxide.
  • • Use special gas cans for refueling of lawn equipment to prevent spillage.
  • 3. Lead

Lead poisoning may be the result of exposure in the indoor environment, outdoor environment, and the occupational environment. Children are especially vulnerable.

They may be exposed through ingestion and inhalation. Lead comes from resource recovery areas, deterioration of lead-based paint indoors and outdoors, waste incineration, battery manufacturing, and the use of leaded gasoline in piston engine aircraft. (The most common sources are mobile sources and the industrial processes.) Secondary lead smelters produce lead from scrap and are the primary means of recycling lead acid automotive batteries. The basic operations of breaking the batteries, smelting, and refining as well as fugitive sources release 1,3 butadiene, a known carcinogen, as well as lead compounds into the air. The particulate matter released can cause severe respiratory problems and the carbon monoxide can cause adverse health effects. In addition, lead damages the nervous system in children especially and the cardiovascular and renal systems in adults.

Best Practices for Lead (See Chapter 4, “Children’s Environmental Health Issues,” Best Practices for Lead section)

  • • Use fabric filters, wet scrubbers, or electrostatic filters to remove dust containing lead during the primary lead production process.
  • • Use baghouse filters to remove dust with lead from emissions in secondary lead production facilities.
  • • Control fugitive lead dust and smelting operations, and transportation to and from the smelter.
  • 4. Nitrogen Oxides

The process of combustion should maximize fuel economy, minimize carbon monoxide and partially oxidize organic compounds, and minimize the volume of air in the furnace. This is typically accomplished by rapid and complete fuel air mixing with adequate time for oxidation. However, this also produces higher levels of nitrogen oxides. To minimize the nitrogen oxides, it is necessary to reduce the gas stream temperatures, minimize the amount of oxygen used, minimize the mixing rates of fuel and air, and have as large a furnace as possible for combustion. Nitrogen oxides are produced primarily from fuel combustion especially in electric utilities, industrial boilers, and all types of wood-burning fireplaces and appliances. Electrical utilities and industrial boilers create about 40% of the nitrogen oxides released to the air.

Further, although motor vehicles individually only contribute small amounts of nitrogen oxides, carbon monoxide, hydrocarbons, and particulate matter, as a group they are a very significant source of all of these air pollutants. Nitrogen oxides (especially nitrogen dioxide) cause irritation and damage to the lungs, lowering resistance to respiratory infections. Frequent exposure to high levels of nitrogen oxides increases the amount of acute respiratory illness in children.

Nitrogen oxides react in the atmosphere to form ozone and acid rain. Nitrogen oxides have caused eutrophication in the coastal waters of the United States, especially in the Chesapeake Bay. They are destructive to fish and other animal life.

Best Practices for Nitrogen Oxides (See endnotes 44, 62)

  • • Modify combustion systems to minimize peak temperatures and the amount of time necessary for combustion of the fuel at the peak temperatures at industrial sites.
  • • Use catalytic converters to reduce nitrogen oxides to nitrogen and oxygen. They also convert hydrocarbons into carbon dioxide and water, and carbon monoxide into carbon dioxide.
  • • Use low nitrogen oxides burners for industrial and utility boilers which utilize such techniques at low excess air, high-efficiency combustion, and recirculation of combustion gases in the flue gas.
  • • Use recirculation of exhaust gases in motor vehicles to reduce the nitrogen oxides.
  • • Use proper maintenance of motor vehicles to ensure appropriate air-fuel ratios, gas compression ratios, and spark timing.
  • • Avoid hard acceleration of motor vehicles to reduce nitrogen oxides, carbon monoxide, and hydrocarbons.
  • • Use energy conservation techniques in buildings to save energy and use less fuel.
  • • Use continuous emission monitoring systems to measure and record nitrogen oxides emissions from stationary sources.
  • 5. Particulate Matter

Both respirable particulate matter (PM10) (dust is the most common source) and fine particulate matter (PM2.5) (dust is the most frequent source followed by fuel combustion in residential housing and electric power plants) increase respiratory problems and lung damage, may cause cancer and premature death, and are also responsible for surface soiling and reduced visibility.

All sizes of particulates may come from power plants, steel mills, chemical plants, grain elevators, and other industrial sources. They may also come from unpaved roads, parking lots, wood-burning stoves, fireplaces, and mobile sources. Typically, there is a continuum of sizes of the particles and therefore you will find both PM10 and PM25 mixed together. There is a seasonal nature to PM2.5 contamination. In the Eastern United States, there are more sulfates from sulfur dioxide contamination during July-September coming from electric power plants. In the Western United States, there is a greater concentration of PM25 caused by fine particulate nitrates formed in cooler weather, and more carbon from wood stoves and fireplaces during cooler weather. Particulate matter can consist of fine dust, soot, smoke, and droplets from chemical reactions. The inhalable coarse particles range in size from 10 pm (PM10) to 2.5 pm (PM25), about the diameter of a human hair. (See endnote 14.)

Primary particles come directly from a source such as a construction site, unpaved road, field, smokestack, or fire. The secondary air pollutants are very small at the 2.5 pm or less level and typically are formed in the atmosphere from emissions from power plants, industries, and cars. The secondary air pollutants are primarily sulfates, nitrates, and carbon compounds. They may cause or contribute to a variety of illnesses, especially among the elderly, children, and those with lung diseases, heart diseases, or asthma. They also reduce visibility in national parks and wilderness areas. Fine particles can remain in the air and travel hundreds of miles or more.

Fugitive dust is particulate in nature and may originate indoors or outdoors from industrial or commercial operations and from unintended consequences of disturbing soil by wind or human activities. The dust particles may contain oxides of silicone, aluminum, calcium, and iron as well as sea salt, pollen, and spores. They may be in the PM10 range or PM2.5 range. Some activities that create fugitive dusts in the industrial sectors of agriculture, mining, construction, manufacturing, transportation and utilities, wholesale trade, retail trade, and services include loading and unloading of material; disturbing the soil and site maintenance; equipment and truck use; storage and dispensing of products; and removal of waste materials. (See endnote 22.)

Best Practices for Particulate Matter

  • • Apply chemical dust suppressants or water to unpaved roads and bare soil in areas where there is traffic and construction.
  • • Choose cleaner fuels such as natural gas, which emits almost no particulate matter.
  • • Use low ash fossil fuels for combustion.
  • • Clean the coal before combustion to reduce ash.
  • • Use more efficient technologies for industrial processes.
  • • Use gasification products of coal instead of coal as a fuel.
  • • Use filters, dust collectors, and electrostatic precipitators, with scrubbers to remove dust particles from gas streams.
  • • Reduce dust in the cement industry by appropriate dust collection systems applied to the air as it leaves the processing and production areas.
  • • Reduce dust in coal processing by using a dust collection system using principles of ventilation, or use a wet suppression system through surface wetting or airborne wetting.
  • • Use appropriate pollution control equipment.
  • • Reduce fuel combustion by improving various technologies related to the product.
  • • Use continuous emission monitoring systems to record and report particulate emissions from stationary sources.
  • 6. Sulfur Dioxide

Sulfur dioxide is produced during the combustion of fuel (most common source), especially high sulfur coal, by coal or oil burning electrical utilities, industries, refineries, and diesel engines. Ninety percent of the sulfur dioxide emissions come from power plants, petroleum refineries, fertilizer manufacturers, paper mills, copper smelters, and iron and steel mills. Sulfur dioxide aggravates asthma, increases respiratory problems, and reacts in the atmosphere to help form acid rain (see the section “Nitrogen Oxides” above).

Best Practices for Sulfur Dioxide (See endnote 63)

  • • Only use low-sulfur coal as a fuel.
  • • Prewash the coal before using as a fuel.
  • • Scrub the sulfur dioxide from the exhaust gases before releasing them into the atmosphere.
  • • Use natural gas instead of high sulfur coal.
  • • Use reactive lime to remove the elemental sulfur, or sulfates.
  • • Alter the industrial process where possible to remove the sulfur and sulfur compounds.
  • • Use continuous emission monitoring systems to record and report sulfur dioxide emissions from stationary sources.

In addition to the six criteria pollutants, there are other sources of pollutions as described below:

1. General Pollutant Sources

The six criteria pollutants, greenhouse gases and hazardous air pollutants come from stationary sources, mobile sources, and area sources, and may travel long distances rapidly, and may be deposited on land or water, dry or wet. They may interact with each other to form new even more complex pollutants, be highly bioaccumulative going from low levels of concentration in water contaminated by air pollution to high levels of concentration in animal tissue, be highly toxic at very low doses, and persist for long periods of time. They may interact with the environment, stick to surfaces to become available at later dates, or re-volatilize into the air and start the process all over again. Typically, pollutants are evaluated individually; however, they are usually present in various combinations and therefore the results of their presence and the potential damage they cause may be hard to predict. Pollutants listed under General Pollutant Sources may be criteria air pollutants, acid rain sources, greenhouse gases, and/or hazardous air pollutants. Specific high-polluting stationary sources and area sources will be discussed later in this chapter under Specific Sources.

2. Stationary Sources (See endnote 59)

The discussion of stationary sources, which are point sources, will be general in nature because the information applies to many of the specific areas listed, such as chemical plants, electric power plants, publicly owned wastewater treatment plants, etc. The individual utilizing this book should first read the stationary sources information and then go to the specific area of interest to enhance his/her knowledge.

Stationary sources typically are a variety of industries including major sources and smaller sources, which may start with the mining of the raw material, the storage of the raw material at the mining area, the storage of fuel to be used for process energy and heating (typically fossil fuels) at the industrial site, the storage at the industrial site of other raw materials to be used in the industrial processes at the plant, the storage of the finished products, and the storage and disposal of wastes. (The various stages of transportation are included below under Mobile Sources.)

Stationary sources emit a variety of inorganic and organic air pollutants as particulates and/or gases depending on the fuels being used in the industrial process of the plant. The industrial plant pollutants may also include sulfur oxides, nitrogen oxides, carbon monoxide, and carbon dioxide. The fuel being used may add the criteria pollutants and/or hazardous air pollutants. Other pollutants, especially hazardous air pollutants, may be created and released depending on the specific processes carried out at the individual facility.

These pollutants may come from the actual processes where incomplete chemical reactions and secondary reactions allow raw materials, impurities, and byproducts to be released into the air. Volatile organic solvents can escape as fugitive emissions from a number of places within the equipment used for the processing of the products. Bad odors may be released in the exhaust, and heating or drying processes. Flaring, which can be very useful for getting rid of excess gases, can also if operated improperly produce excessive amounts of sulfur dioxide and a group of hazardous air pollutants.

Four major locations in industrial production which may lead to discharge of air pollutants may be:

  • 1. Process operations, such as emissions from the reactor vents, distillation systems, and spray drying
  • 2. Fugitive sources, such as emissions from valves, pressure relief devices, and equipment cleaning and maintenance
  • 3. Surface area sources, such as evaporation from holding ponds, cooling towers, wastewater treatment areas
  • 4. Handling, storage, and loading areas, such as storage tanks and line venting

Best Practices for Stationary Sources (also see General Best Practices for All Sources of Air Pollution section) (See endnote 61)

  • • Eliminate the source of the problem in the industrial process.
  • • Change the industrial operation to reduce the level of air pollutants.
  • • Make the industrial operation more efficient, which also produces greater profits for the industry.
  • • Adjust various pieces of equipment such as burners, boiler doors, etc., to reduce nitrogen oxides emissions.
  • • Make industrial boilers using fossil fuels more efficient by proper maintenance, reducing excess air, eliminating leaks, insulating pipes, automatically controlling use of fuel, and switching from coal or oil to natural gas.
  • • Make electric motors for various industrial applications more efficient by using modern flat belts instead of V belts, adjust the components of the motor properly, or replace with energy efficient motors.
  • • Use cogeneration of heat and power to extract most of the energy that is available in the fuel.
  • • Use appropriate size smokestacks to dilute small amounts of pollutants but not carry them downwind to other areas.
  • • Pretreat raw materials before use to reduce the level of potential pollutants released during the actual industrial process.
  • • Substitute less polluting materials for more polluting materials.
  • • For particulate control, use wet and dry electrostatic precipitators, fabric filters, venturi scrubbers, cyclones, and settling chambers.
  • • To control gaseous emissions, use thermal oxidizers, catalytic reactors, flares, boilers and process heaters, carbon absorbers, absorbers, condensers, and biofilters.
  • 3. Mobile Sources

Mobile sources are divided into on-road sources and off-road sources. Mobile sources regulated by the EPA include: commercial aircraft; heavy-duty vehicles, buses, recreational vehicles, and semi-trailers; light-duty vehicles, cars, minivans, and SUVs; diesel-powered engines on locomotives; motorcycles; a variety of boats and ships; construction and agricultural equipment; gasoline and propane industrial equipment; lawn and garden equipment; and snowmobiles, dirt bikes, etc. These mobile sources pollute the air through combustion of fuel and fuel evaporation. They produce carbon monoxide, hydrocarbons, nitrogen oxides, and particulate matter as well as air toxics and greenhouse gases. Mobile sources are the largest contributors to air toxics. Diesel exhaust from freight vehicles is a primary source of PM25, air toxics, nitrogen oxides, and approximately one third of the greenhouse gas emissions in the United States. (See endnote 20.) In New Jersey, as of the US EPA’s 1999 Air Toxics Inventory, on-road and non-road mobile sources accounted for 61% of the air toxics inventory. Area and other sources accounted for 27% of the air toxics. Only 12% were from major source contributors. (See endnote 16.)

An environmental justice issue is created by mobile sources in heavily industrialized areas of the city because the diesel semi-truck traffic around industrial plants use the same routes every day moving raw materials and finished products and therefore contribute heavily to air pollutants. This may lead to a substantial increase in disease for residents of the surrounding area.

Best Practices for Mobile Sources

  • • The US EPA established standards for specific pollutants being emitted by mobile sources including vehicles, engines, and equipment.
  • • The US EPA established sulfur dioxide emission standards for gasoline, on-road diesel fuel, and off-road diesel fuel which is being used in mobile sources.
  • • People selling a vehicle or engine within the United States have to show compliance with the Clean Air Act.
  • • Manufacturers, in order to meet the standards, design and implement efficient combustion systems, vapor recovery systems, computer technology to monitor and control the performance of the engines, catalytic converters, and particulate filters to remove the pollutants from the exhaust.
  • • Use reformulated gasoline to reduce emissions of benzene, toluene, and other toxic pollutants.
  • • Establish limits for tailpipe emissions of toxic pollutants and enforce them.
  • 4. Acid Rain

Acid rain, acid snow, acid fog, acid mist, or dry forms of acid deposition are formed in the atmosphere and fall to the earth. The acid deposition changes the chemistry of the soil and bodies of water. It may destroy or alter ecosystems. The acid deposition causes health problems, hazy skies, and property damage, and can affect agricultural crops. The acid precipitation is formed when sulfur dioxide and nitrogen oxides are emitted to the air and react with water vapor and other chemicals to create acids.

Best Practices for Acid Rain

  • • Reduce the quantity of emissions of sulfur dioxide and nitrogen oxides from power plants and automobiles.
  • • Reduce the amount of electricity used by turning off lights, computers, and appliances that are not being used at a particular time.
  • • Purchase only energy-efficient appliances and phase out the older ones.
  • • Reduce the thermostat during the winter and raise it during the summer to decrease fuel use.
  • • Use appropriate maintenance programs for all motor vehicles and various motorized equipment and tools.
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