Chapter 15: Air Pollution and Stratospheric Ozone Depletion (APES)

Air pollution

The introduction of chemicals, particulate matter, or microorganisms into the atmosphere at concentrations high enough to harm plants, animals, and materials such as buildings, or to alter ecosystems

Particulate matter (PM)

Solid or liquid particles suspended in air.

Haze

Reduced visibility

Photochemical oxidant

A class of air pollutants formed as a result of sunlight acting on compounds such as nitrogen oxides

Ozone (O3)

A secondary pollutant made up of three oxygen atoms bound together

Smog

A type of air pollution that is a mixture of oxidants and particulate matter

How does Chattanooga's geography exacerbate its air pollution problems?

Chattanooga is located in a bowl formed by surrounding mountains; this geography traps pollutants that hover above the city

Why did Chattanooga continue to have an ozone problem even after cleaning up other types of air pollution?

Automobiles precursors within and beyond city limits

What are two anthropogenic sources and two natural sources of air pollution?

Motor vehicles and fossil fuel combustion anthropogenic sources

Forest fires and lighting - natural sources

Why is air pollution a global problem? Support your answer with examples.

Since one of the major repositories for air pollutants is the atmosphere, which envelops the entire globe, we must think of the air pollution system as a global system

What did the Clean Air Act originally target? What other pollutants should be added to the Clean Air Act?

The original act identified six pollutants that significantly threaten human well-being, ecosystems, and structures: sulfur dioxide, nitrogen oxides, carbon monoxide, particulate matter, tropospheric ozone, and lead. Mercury and CO2 should be added

Carbon monoxide (CO)

- (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.

Nitrogen oxides

- nitrogen oxide (NO), a colorless, odorless gas; and nitrogen dioxide (NO2), a pungent, reddish-brown gas

- All combustion in the atmosphere including fossil fuel combustion, wood, and other biomass burning (anthropogenic)

Sulfur dioxide

- corrosive gas that comes primarily from combustion of fuels such as coal and oil

- released in large quantities during volcanic eruptions and smaller quantities, during forest fires

- Combustion of fuels that contain sulfur, including coal, oil, gasoline (anthropogenic)

PM 2.5 sources

Agriculture, road construction, and other activities that mobilize soil, soot, and dust (natural)

What is an anthropogenic source of particulate matter? What is a natural source?

Anthro: Burning fossil fuels, agriculture, road construction

Natural: volcano

How does the size of PM affect our concern about it?

We can filter out the larger particles with the lining found in the nose and throat

The amount of lead in the atmosphere has decreased over time. Why hasn't this been the case for mercury?

It is uncontrolled when mercury is produced through coal burning. Lead was reduced through catalytic converters

Even though VOCs aren't necessarily hazardous, why are they still considered air pollutants?

Lead to photochemical oxidants, so can be harmful

Photochemical smog (Los Angeles- type Smog; Brown smog)

Smog that is dominated by oxidants such as ozone

Sulfurous smog (London-type smog; Gray smog; Industrial smog.)

Smog dominated by sulfur dioxide and sulfate compounds

Volatile organic compound (VOC)

An organic compound that evaporates at typical atmospheric temperatures

Primary pollutant

A polluting compound that comes directly out of a smokestack, exhaust pipe, or natural emission source

- Ex: CO and CO2

Secondary pollutant

A primary pollutant that has undergone transformation in the presence of sunlight, water, oxygen, or other compounds

- Ex: Ozone and nitrate

What are the National Ambient Air Quality Standards?

Limits on atmospheric concentration of six pollutants that cause smog, acid rain, and other health hazards

What two air pollutants are major contributors to smog formation?

Nitrogen oxides and Sulfur dioxides

What is the chemical equation of ozone formation?

No2 → NO+O → O+O2 → O3

What is a natural & anthropogenic source of VOCs?

Natural:plants

Human: dry, cleaning fluid

How does temperature influence smog formation? Why?

more ozone forms when higher temperatures because they need sunlight for the reaction to occur

How does an inversion layer influence smog formation? Why?

The warm inversion layer traps emission that then accumulates beneath it

What causes rain to be naturally acidic? What is the pH of natural rain?

Volcanoes and decaying vegetation naturally increase the acidity of rain, while the burning of fossil fuels are the primary man-made causes of acid rain. Ph is between 5 and 5.5

What is a natural process that causes acid deposition?

Condensation- pollutants such as so2 and nox combined with o2 to form acid, which combines with h2o, creates clouds and falls to earth as acid rain

How has the US reduced acid deposition?

Result of lower sulfur dioxide and nitrogen oxide emissions due to the Clear Air Act Amendments in 1990 and 95

Ground level pollution

air pollution that occurs in the troposphere, the first 16 km (10 miles) above Earth's surface

Atmospheric brown cloud

combination of particulate matter and ozone

NAAQS (National Ambient Air Quality Standards)

are pollution standards for six priority pollutants set by the Environmental Protection Agency through the Clean Air Act

Is acid deposition a local, regional or global problem? Explain.

Regional problem. Acid deposition is original problem that occurs across the world, globally

What are the 2 most common forms of acid deposition? What are their chemical formulae?

Nitrogen oxides (NO/NO2) and sulfur dioxides (SO2)

What type of ecosystem is most affected by acid deposition? What happens that causes so much ecosystem harm?

Aquatic ecosystems. Lower pH of lakes and streams caused decreased species diversity of aquatic organisms. Can also lead to mobilization of metals, an indirect effect

How does acid deposition release heavy metals into water?

Metals bound in organic or inorganic compounds in soils and sediments are released into surface water

What compound in building marble is susceptible to acid deposition?

calcium carbonate

List the environmental, economic and human health impacts associated with acid rain.

Envio: aquatic environments, such as streams, lakes, and marshes where it can be harmful to fish and other wildlife

Economic: Power generating plants and other major producers of acid rain discharge their oxide wastes into the air in order to reduce production costs

Human Health: Air pollution like sulfur dioxide and nitrogen oxides can cause respiratory diseases, or can make these diseases worse

List some ways to PREVENT air pollution.

Avoid them , use low-sulfur coal or oil, and increased efficiency and conservation

How can we control sulfur dioxide emissions? Include any drawbacks to the control methods.

Fluidized bed combustion → granulated coal is burned in close proximity to calcium carbonate. The heated calcium carbonate absorbs sulfur dioxide and produces calcium sulfate, which can be used in the production of sheetrock, for houses

How can we control nitrogen oxide emissions? Include any drawbacks to the control methods.

Burn temperatures must be reduced and the amount of oxygen must be controlled. However, lowering temperatures and oxygen supply can result in less-complete combustion, which reduces the efficiency of the process and increases the amount of particulates and carbon monoxide

How can we control particulate matter emissions? Include any drawbacks to the control methods.

Gravitational settling, which relies on gravity as the exhaust travels through the smokestack. The particles simply settle out to the bottom. The ash residue that accumulates must be disposed of in a landfill. Fabric filters are a type of filtration devices that allow gases to pass through them but remove particulate matter

Thermal inversion

A situation in which a relatively warm layer of air at mid-altitude covers a layer of cold, dense air below

Inversion layer

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

Acid deposition

Sulfur oxides and nitrogen oxides, emitted by burning fossil fuels, enter the atmosphere-where they combine with oxygen and water to form sulfuric acid and nitric acid-and return to Earth's surface

Sulfur allowances

awarded annually to existing sulfur emitters proportional to the amounts of sulfur they were emitting before 1990 --> can be bought and sold

Baghouse filter

type of filtration device that allow gases to pass through them but remove particulate matter

Scrubber

Air pollution control device where particles are "scrubbed" from the exhaust stream by water droplets. A water-particle "sludge" is collected and processed for disposal

How does an electrostatic precipitator work? What does it remove?

Use an electrical charge to make particles coalesce so they can be removed. Polluted air enters the precipitator and the electrically charged particles within are attracted to negative or positive charges on the sides of the precipitator. The particles collect and relatively clean gas exits the precipitator

Describe 2 methods cities have employed to reduce photochemical smog.

Reduce it precursors: VOCs and nitrogen oxide

How did the Clean Air Act successfully reduce SO2 emissions?

Allows the free market to determine the least expensive ways to reduce emissions. Allows the buying and selling of allowances

What are the 3 types of UV radiation? Which type of UV radiation is most dangerous? What are 3 health effects of this?

UV-A, or low-energy ultraviolet radiation, and the shorter, higher-energy UV-B and UV-C wavelengths. UVB is the most dangerous. increases the risk of skin cancer and suppresses the immune system. It also harms the cells of plants, and it reduces their ability to convert sunlight into usable energy

What are the benefits of stratospheric ozone?

absorbs radiation from sun, therefore protects life on earth

What chemicals cause ozone loss?

chlorofluorocarbons (CFCs)

What is the chemical reaction that causes the formation of stratospheric ozone? Write down 3 equations below.

1. O2 + UVC → O + O

2. O + O2 → O3

3. O3 + UVB or UVC → O2 + O

CFCs

Chlorinated Fluorocarbons are chemicals that break down the ozone layer

Montreal Protocol

This was a commitment to reduce CFC production by 50 percent by the year 2000

Asbestos

A long, thin, fibrous silicate mineral with insulating properties, which can cause cancer when inhaled

Radon

a radioactive gas that occurs naturally from the decay of uranium, exists in granitic and some other rocks and soils in many parts of the world

Sick building syndrome

A buildup of toxic pollutants in an airtight space, seen in newer buildings

What is the chemical reaction that causes the breakdown of stratospheric ozone? Write down 2 equations below.

1. O3 + Cl → ClO + O2

2. ClO + O → Cl + O2

Where and when (months and season) does the ozone hole form?

In the Antarctic, ozone depletion was seasonal: Each year the depletion occurred from roughly August through November (late winter through early spring in the Southern Hemisphere).The depletion caused an area of severely reduced ozone concentrations over most of Antarctica

What is the main source of indoor air pollution in developing countries?

Biomass

Who is most affected by indoor air pollution in developing countries? What is a likely explanation for this?

Africa. This is because there are tons of people there who all create things using industry, and there are also tons of vehicles in Africa

What are 3 reasons why indoor air pollution has become a greater concern in developed countries?

Agricultural land, industrial and vehicle emissions, and the burning of forests

What are some symptoms of Sick Building Syndrome (SBS)? According to the EPA, what are 4 causes of SBS?

Symptoms: headache; eye, nose, or throat irritation

4 causes:

- Buildings with poor ventilation, such as schools, offices, and public spaces.

high levels of dust.

- Tobacco smoke.

- Rooms with poor lighting.

- Asbestos

How do households in China, India and sub-Saharan Africa typically cook food? What problems do this cause?

80-90% of houses cook food using wood, animal manure, and crop residue as fuel. This indoor pollutant creates PM, carbon monoxide, and 1.6 million deaths annually and 200x the EPA recommended exposure limit

Describe some of the options for better cook stoves. Include any trade-offs.

Efficient cooking stoves, ventilated cooking areas, and cooking outside. This improves air quality, reduces fuel needed, and has environmental benefits. Cook stoves for backpacker and other outdoorsmen can be used to cook outside with no gasoline nor batteries. BioLute physically separates solid fuel from the gases that form when the fuel is burned and allows a small electric fan inside to ensure full combustion