Unit 7-Atmospheric Pollution

Grasshopper Effect

: Is based on atmospheric distillation which transfer volatile air pollutants from tropical and temperate areas to the Earth's poles. It occurs when volatile compounds evaporate from warm terrestrial areas at low latitudes and rise high into the atmosphere. Then they are deposited in the oceans or carried to higher latitudes at or near the Earth's poles by atmospheric currents and oceanic currents of water. This explains why for decades pilots have reported dense layers of reddish-brown haze over the Arctic. It also explains why polar bears, whales, sharks, and other top carnivores and native peoples in the Arctic have high levels of DDT and other long-lived pesticides, toxic metals (such as lead and mercury), and polychlorinated biphenyls (PCBs) in their bodies even though there are no concentrations of industrial facilities and cars in these remote areas.

Environmental Protection Agency (EPA)

A U.S. government agency that creates federal policy and oversees enforcement of regulations related to the environment, including science, research, assessment, and education.

Cyclone Separator

A centrifugal separator where the particles are swung as a result of their mass by the centrifugal force to the outside. Entering air is automatically forced a rapidly spinning double vortex movement, so-called "double-vortex". This double vortex movement exists from the outside stream, that flows spirally down and the inside stream that flows spirally up. On the border area of both flows the air flows from one to the other. The particles present in the air flow are swung to the outside wall and leaves the separator by means of a reception space situated to the base.

Nitrous Oxide (N2O)

A greenhouse gas. Human sources include fossil fuel burning, fertilizers, livestock wastes, and nylon production.

Atmospheric Pressure

A measure of the mass per unit area of air.

Nonattainment Area

A region that does not meet ozone guidelines set by the EPA.

Asthma

A respiratory disease that sometimes starts early in life. Asthma is typically an allergic reaction causing muscle spasms in the bronchial walls and acute shortness of breath.

Ozone (O3)

A secondary pollutant made up of three oxygen atoms bound together.

Mercury (Hg)

A trace metal found in coal and oil and, like lead, is toxic to the central nervous system of humans and other organisms. The EPA regulates this element through its hazardous air pollutants program. As a result of the release of it into the air (primarily from the combustion of fossil fuels, especially coal), the concentrations of this element in both air and water have increased dramatically in recent years. As a result of bioaccumulation, high concentrations of this element have been found in some fish species. People who eat these fish increase their own concentrations of this highly toxic element - an example of the interconnectedness of air pollution, air, water, aquatic health, and human health.

Prevention Approaches

According to most scientists studying the problem of acid deposition, the best solutions are those approaches that reduce or eliminate emissions of SO2, NOx, and particulates.

Indoor Air Pollutants

According to the EPA and public health officials, the four most dangerous indoor air pollutants in developed countries are cigarette smoke, formaldehyde, radioactive radon-222 gas, and very small fine and ultrafine particles.

Dry Deposition

Acidic substances that descend to the Earth's surface as acidic particles. This typically occurs within about 2-3 days fairly near the emission sources.

Wet Deposition

Acidic substances that descend to the Earth's surface as acidic rain, snow, fog, and cloud vapor with a pH less than 5.6. Usually takes place within 4-14 days in more distant downwind areas.

Los Angles Type Smog

Also referred to as photochemical smog or brown smog.

Radiation Temperature Inversion

An air event that typically occurs at night in which a layer of warm air lies atop a layer of cooler air nearer the ground as the air near the ground cools faster than the air above it. As the sun rises and warms the earth's surface, the inversion normally disappears by noon and disperses the pollutants built up during the night.

Soot

Is also referred to as black carbon aerosols. Is primarily produced from incomplete combustion in coal burning, diesel engines, and open fires. It could be the second biggest human contribution to global warming, after the greenhouse gas CO2.

Primary Standard

Is an air quality standard set by the EPA to protect human health.

Photochemical Reaction

Is any chemical reaction activated by light. Air pollution known as photochemical smog is formed when a mix of nitrogen oxides (NO and NO2, both called Nox) and volatile organic hydrocarbon compounds from natural and human sources chemically react under the influence of UV radiation from the sun to produce a mixture of more than 100 primary and secondary pollutants.

Acid Shock

Is caused by the sudden runoff of large amounts of highly acidic water and aluminum ions into lakes and streams when snow melts in the spring or after unusually heavy rains.

UV-C

Is even stronger than UV-B but it never reaches the Earth's surface because it is filtered out by the atmosphere.

UV-B

Is stronger than UV-A, is the most harmful to us and other life forms. Causes skin cancer and cataracts - a permanent clouding of the eye which reduces vision. Both this ultraviolet radiation and UV-A cause suntans and sunburns. UV-B also reduces the growth of plants, and may affect the health of wildlife and other animals.

UV-A

Is the weakest form of ultraviolet radiation. It causes skin aging, wrinkles and can also damage outdoor plastics and paint.

Clean Air Act of 1970

Law that established national standards for states, strict auto emissions guidelines, and regulations which set air pollution standards for private industry.

Density

Mass per unit volume. This property of air decreases as altitude increases in the troposphere.

Toxic Release Inventory (TRI)

Measurements of hazardous air pollutants (HAPs) are made in abut 50 locations in the United States. One of the best sources of information about these chemicals in your local area is an annual report inventoried and released to the public as part of community right to know laws enacted by Congress in 1986.

Emissions Trading Policy

An approach used to control pollution by providing economic incentives for achieving reductions in the emissions of pollutants. To help reduce SO2 emission, the Clean Air Act of 1990 allows this, which enables the 110 most polluting power plants in 21 states (primarily in the Midwest and East) to buy and sell SO2 pollution rights. This process begins with each of the coal-burning plants measuring the sulfur dioxide emitted from their smokestacks. Each year, a coal-burning power plant is given a certain number of pollution credits, or rights to emit a certain amount of SO2. A utility that emits less SO2 than its limit has a surplus of pollution credits. It can use these credits to avoid reductions in SO2 emissions at another of its plants, keep them for future plant expansions, or sell them to other utilizes, private citizens, or environmental groups.

Dust Dome

An area of heated air that surrounds an urban area and traps pollutants, especially suspended particulate matter.

Particles

Another name for particulate matter or particulates.

Ground-Level Pollution

Another name for tropospheric pollution.

Nitrogen Oxides

Are generically designated NOx, with the X indicating that there may be either one or two oxygen atoms per nitrogen: nitrogen oxide (NO), a colorless, odorless gas, and nitrogen dioxide (NO2), a pungent, reddish-brown gas, respectively. Motor vehicles and stationary fossil fuel combustion are the primary anthropogenic sources of these. Natural sources include forest fires, lightning, and microbial action in soils. They play a role in forming tropospheric ozone and other components of photochemical smog.

Lichens

Are not plants, they consist of a fungus and an alga living together, usually in a mutually beneficial (mutualistic) relationship. Some species are very sensitive to specific air-polluting chemicals and can be used effectively as indicator species.

Legionella pneumophila

Bacterium that causes a disease in the lungs, spread by air conditioning equipment.

Primary Pollutant

Chemical that has been added directly to the air by natural events or human activities and occurs in a harmful concentration.

Coal Gasification

Coal can be converted to gaseous and liquid fuels that burn cleaner than coal, but costs are high, and producing and burning them add more carbon dioxide to the atmosphere than burning coal.

Photochemical Oxidants

Collectively, NO2, O3, and PANs are called this because they can react with and oxidize certain compounds in the atmosphere or inside your lungs that normally are not oxidized. Mere traces of these oxidants (especially ozone) and aldehydes in photochemical smog can irritate the respiratory tract and damage crops and trees).

National Ambient Air Quality Standards (NAAQS)

Congress directed the EPA to establish air quality standards for six outdoor criteria pollutants (carbon monoxide, nitrogen dioxide, sulfur dioxide, suspended particulate matter, ozone, lead). The EPA regulates these chemicals by using criteria developed from risk assessment methods to set maximum permissible levels in outdoor air.

Suspended Particulate Matter

Consists of particles of solid matter and droplets of liquid that are small and light enough to remain present in the atmosphere for some period (the larger the particle, the sooner it usually falls to Earth). Are found in a wide variety of types and sizes, ranging in diameter from 0.001 micrometer to 100 micrometers (a micrometer, or micron, is one-millionth of a meter, or about 0.00004 inch). Since 1987, the EPA has focused on fine particles smaller than 10 microns (known as PM-10). In 1997 the agency began focusing on reducing emissions of ultrafine particles with diameters less than 2.5 microns (known as PM-2.5) because these particles are small enough to reach the lower part of human lungs and contribute to respiratory diseases.

Output Approach

Current air pollution laws are a useful way to controlling air pollution. To environmentalists, however, the next step is to shift to preventing air pollution. In this way, the question is not What can we do about the air pollutants we produce? But How can we avoid producing such pollutants in the first place?

Sulfurous Smog

Dominated by sulfur dioxide and sulfate compounds. Also known as London-type smog; gray smog; and industrial smog

Dust Plume

Elongation of a dust dome by winds that can spread a city's pollutants hundreds of kilometers downwind.

Secondary Pollutant

Harmful chemical formed in the atmosphere when a primary air pollutant reacts with normal air components or other air pollutants.

Cilia

Hundreds of thousands of tiny mucus-coated hair-like structures called cilia line your upper respiratory tract. They continually wave back and forth and transport mucus and the pollutants they trap to our throat (where they are swallowed or expelled).

Welfare

In the Clean Air Act welfare refers to visibility, the status of crops, natural vegetation, animals, ecosystems, and buildings.

Gray-Air Smog

In the troposphere, some of the sulfur dioxide reacts with oxygen to form sulfur trioxide (SO3), which then reacts with water vapor in the air to produce suspended droplets of sulfuric acid (H2SO4). Some of these droplets react with ammonia in the atmosphere to form solid particles of ammonium sulfate [(NH4)2SO4]. The tiny suspended particles of such salts and carbon (soot) give the resulting industrial smog a gray color, explaining why it is sometimes called gray-air smog.

Carbon Oxides

Includes both carbon monoxide (CO) and carbon dioxide (CO2).

Global Warming

Increase in temperature of Earth's atmosphere as a result of increases in the concentrations of one or more greenhouse gases.

Black Triangle

Industrial smog is a problem in some eastern European countries called the "black triangle" region of Slovakia, Poland, Hungary and the Czech Republic, where large quantities of coal are burned with inadequate pollution controls.

Troposphere

Innermost layer of the atmosphere. It contains about 75% of the mass of earth's air and extends about 17 kilometers (11 miles) above sea level.

Carbon Monoxide (CO)

Is a colorless, odorless gas that is formed during incomplete combustion of most matter, and therefore is a common emission in vehicle exhaust and most other combustion processes. This gas can be a significant component of air pollution in urban areas. It also can be a dangerous indoor air pollutant when exhaust systems on natural gas heaters malfunction and, primarily in developing countries, where there may be poor ventilation when cooking with manure, charcoal, or kerosen.

Sulfur Dioxide (SO2)

Is a corrosive gas that comes primarily from combustion of fuels such as coal and oil. It is a respiratory irritant and can adversely affect plant tissue as well. Is also released in large quantities during volcanic eruptions and can be released, though in much smaller quantities, during forest fires.

Radon-222

Is a naturally occurring radioactive gas that you cannot see, taste, or smell and is produced by the radioactive decay of uranium-238. But this isotope is much more concentrated in underground deposits of minerals such as uranium, phosphate, granite, and shale. When gas from such deposits seeps upward through the soil and is released outdoors, it disperses quickly in the atmosphere and decays to harmless levels. However, in buildings above such deposits this radioactive gas can enter through cracks in foundations and walls, openings around sump pumps and drains, and hollow concrete blocks. It tends to be pulled into a house because of the slightly lower atmospheric pressure inside most homes. Once inside it can build up to high levels, especially in unventilated lower levels of homes and buildings. It is the second leading cause of lung cancer after smoking.

Electrostatic Precipitator

Is a particulate collection device that removes particles from a flowing gas (such as air) using the force of an induced electrostatic charge. Are highly efficient filtration devices that minimally impede the flow of gases through the device, and can easily remove fine particulate matter such as dust and smoke from the air stream.

Atmospheric Brown Cloud

Is a relatively new descriptive term that has been given to the combination of particulate matter and ozone. Derived primarily from combustion of fossil fuel and burning biomass, atmospheric brown clouds have been observed in cities and throughout entire regions.

Lead (Pb)

Is a trace metal that occurs naturally in rocks and soil. Was added to gasoline for many years to improve vehicle performance. It was released into the air during combustion and traveled with the prevailing winds and was deposited on the ground by rain or snow, become pervasive around the globe, including polar region. Another persistent source of this element is most paint in older buildings; when the paint peels off, the resulting dust or chips can be toxic to the central nervous system and can affect learning and intelligence, particularly for young children who may ingest the dust or chips, attracted by their sweet taste.

Local Air Pollution

Most coal-burning power plants, ore smelters, and other industrial plants in developed countries use tall smokestacks to emit sulfur dioxide, suspended particles, and nitrogen oxides high into the troposphere where wind can mix, dilute, and disperse them. These tall smokestacks reduce air pollution near where it is produced, but they can increase regional air pollution downwind. This occurs because the primary pollutants, sulfur dioxide and nitrogen oxides, emitted into the atmosphere above the inversion layer are transported as much as 1,000 kilometers (600 miles) by prevailing winds. During their trip, they form secondary pollutants such as nitric acid vapor, droplets of sulfuric acid and particles of acid-forming sulfate and nitrate salts.

Brown-Air Smog

NO2 is the cause of the brownish haze that hangs over many cities during the afternoons of sunny days, explaining why photochemical smog sometimes is called brown-air smog. Sometimes called Los Angeles smog.

pH

Numeric value that indicates the acidity or alkalinity of a substance on a scale of 0 to 14, with the neutral point at 7.

Temperature Inversion

Occurs when a layer of dense, cool air trapped under a layer of less dense, warm air. This prevents upward-flowing air currents from developing. In a prolonged inversion, air pollution in the trapped layer may build up to harmful levels.

Subsidence Temperature Inversion

Occurs with normal air temperature layers when a large mass of warm air moves into a region at a high altitude and floats over a mass of colder air near the ground. This keeps the air over a city stagnant and prevents vertical mixing and dispersion of air pollutants.

Baghouse Filter

One of the most efficient devices for removing suspended particulates is an assembly of fabric filter bags. Dust-laden air is blown upward through the bottom of the enclosure by fans. Particulates are trapped inside the filter bags, while the clean air passes through the fabric and exits at the top of the baghouse. A fabric-filter dust collector can remove very nearly 100 percent of particles as small as 1 mm (0.00004 inch) and a significant fraction of particles as small as 0.01 mm (0.0000004 inch). Fabric filters, however, offer relatively high resistance to airflow, and they are expensive to operate and maintain.

Air Pollution

One or more chemicals in high enough concentrations in the air to (1) harm humans, other animals, vegetation, or materials or (2) alter climate. Excess heat and noise are also considered forms of air pollution. Such chemicals or physical conditions are called air pollutants.

Volatile Organic Compounds (VOCs)

Organic compounds that exist as gases in the atmosphere and act as pollutants, some of which are hazardous.

Wet Scrubber

Particulates, vapors, and gases are controlled by passing the gas stream through a liquid solution. These devices are used on coal burning power plants, asphalt/concrete plants, and a variety of other facilities that emit sulfur dioxides, hydrogen sulfides, and other gases with a high water solubility. Can be used for corrosive, acidic, or basic gas streams.

PANs

Peroxyacyl nitrates. Group of chemicals found in photochemical smog.

Climate

Physical properties of the troposphere of an area based on analysis of its weather records over a long period (at least 30 years). The two main factors determining it are temperature (with its seasonal variations) and the amount and distribution of precipitation.

Chimney (or stack) Effect

Process whereby warmer air rises in buildings to upper levels and is replaced in the lower portion of the building by outdoor air drawn through a variety of openings, such as windows, doors, or cracks in the foundations and walls.

Emphysema

Prolonged smoking and exposure to air pollutants can cause this lung which disease which causes shortness of breath. In people with this condition, the air sacs in the lungs (alveoli) are damaged.

Cap-And-Trade

Proponents of emissions trading policy argue that it allows the marketplace to determine the cheapest, most efficient way to get the job done instead of having the government dictate how to control air pollution.

Haze

Reduced visibility often caused when particulate matter from air pollution scatters light.

Acid Deposition

Refers to the falling of acids and acid-forming compounds from the atmosphere to the Earth's surface.

Human Health

Refers to the medical well-being of the human population and includes the elderly, children, and sensitive populations such as those with asthma.

Fine Particles

Research indicates that especially particles with diameters less than 10 microns (PM-10) and ultrafine particles with diameters less than 2.5 microns (PM-2.5) - pose a significant health hazard. Such particles come from a variety of sources.

Asian Brown Cloud

Satellite images show a dark brown cloud, 3 kilometers (2 miles) thick, stretching nearly continuously across much of India, Bangladesh, and the industrial heart of China and parts of the open sea in this area. This cloud is caused by huge emissions of ash, smoke, dust, and acidic compounds produced by people burning coal in industries and homes and clearing and burning forests for planting crops, along with dust blowing off deserts in western Asia. As the cloud travels, it picks up many toxic pollutants.

Particulate Matter (PM)

Solid or liquid particles suspended in air. Comes from the combustion of wood, animal manure and other biofuels, coal, oil, and gasoline. It is most commonly known as a class of pollutants released from the combustion of fuels such as coal and oil. Diesel-powered vehicles give off more of this than other vehicles. Can also come from road dust and rock-crushing operations. Volcanoes, forest fires, and dust storms are important natural sources. Particles smaller than 10 µm are called PM-10 and particles of 2.5 µm and smaller are called PM-2.5 and are an even greater health concern than PM-10 because they deposit deeply within the respiratory tract and they tend to be composed of more toxic substances than particles in larger size ranges.

Synergistic Effects

Some air pollutants can harm some types of trees through synergistic effects. For example, studies show that no visible injury occurs to white pine seedlings when they are exposed individually to low concentrations of sulfur dioxide and ozone. However, if the seedlings are exposed to the same concentrations of both pollutants simultaneously, visible damage occurs, apparently because the two pollutants interacted synergistically.

Cleaning Solvents

Some industrial cleaning solvents like carbon tetrachloride, methyl chloroform, n-propyl bromide, and hexachlorobutadiene are known to be ozone-depleting compounds.

Asbestos

Sources include fireproofing, insulation, vinyl flooring, and cement products. Effects on humans include skin irritation and lung cancer.

Sick Building Syndrome

Studies have linked various air pollutants found in buildings to dizziness, headaches, coughing, sneezing, shortness of breath, nausea, burning eyes, chronic fatigue, irritability, skin dryness and irritation, and flu-like symptoms. New buildings more commonly have this issue because of reduced air exchange (to save energy) and chemicals released from new carpeting and furniture.

Buffer

Substance that can react with hydrogen ions in a solution and thus hold the acidity or pH of a solution fairly constant.

Criteria Air Pollutants

The Clean Air Act identified six pollutants that significantly threaten human well-being, ecosystems, and/or structures: sulfur dioxide, nitrogen oxides, carbon monoxide, particulate matter, tropospheric ozone, and lead. They are called this because under the Clean Air Act, the EPA must specify allowable concentrations of each pollutant.

Hazardous Air Pollutants (HAPs)

The EPA has established national emission standards for more than 188 dangerous air pollutants that may cause serious health and ecological effects. These chemicals include neurotoxins, carcinogens, mutagens, teratogens, endocrine system disrupters, and other toxic compounds. Most of these chemicals are chlorinated hydrocarbons, volatile organic compounds, or compounds of toxic metals.

Formaldehyde

The chemical that causes most people in developed countries difficulty is a colorless, extremely irritating gas widely used to manufacture common household materials. According to the EPA and the American Lung Association, 20-40 million Americans suffer from chronic breathing problems, dizziness, rash, headaches, sore throat, sinus and eye irritation, wheezing, and nausea caused by daily exposure to low levels of this chemical that is emitted from common household materials. Sources include building materials (such as plywood, particleboard, paneling, and high-gloss wood used in floors and cabinets), furniture, drapes, upholstery, adhesives in carpeting and wallpaper, some types of insulation, fingernail hardener, and wrinkle-free coating on permanent-press clothing.

Inversion Layer

The layer of warm air that traps emissions in a thermal inversion.

Weather

The troposphere is the layer of the atmosphere involved in the chemical cycling of the Earth's vital nutrients. This thin, turbulent layer of rising and falling air currents and winds is largely responsible for our planet's short-term changes in surface atmospheric conditions.

Fluidized-Bed Combustion

This is method of burning coal which reduces pollutant emissions. Coal burns more efficiently because a stream of hot air is blown into a boiler containing a mixture of powdered coal and crushed limestone.

Sensitive Areas

Two types of regions are vulnerable to acid deposition because they lack the buffering capacity needed to neutralize the acidic compounds falling from the sky. One has areas with thin acidic soils derived mostly from granite rock without such natural buffering. The other is areas where the buffering capacity of soils has been depleted by decades of acid deposition.

Industrial Smog

Type of air pollution consisting mostly of a mixture of sulfur dioxide, suspended droplets of sulfuric acid formed from some of the sulfur dioxide, and a variety of suspended solid particles.

Ultrafine Particles

Ultrafine particles are invisible particles with diameters less than 2.5 microns (PM-2.5). These extremely small particles pose significant health hazards.

Smog

Was originally described as a combination of smoke and fog but the term is now used to describe other mixtures of pollutants in the atmosphere.

Atmosphere

Whole mass of air surrounding the Earth.

Chronic Bronchitis

Years of smoking and breathing air pollutants can lead to respiratory disorders including lung cancer and this chronic condition. Involves persistent inflammation and damage to the cells lining the bronchi and bronchioles. The results are mucus buildup, loud, painful coughing, and shortness of breath.