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Samenvatting Milieubeleid & Compartimenten
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Dit is een samenvatting voor het vak Milieubeleid & Compartimenten.
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SAMENVATTING M&C: LUCHT EN GELUIDLIVING IN THE ENVIRONMENT
CHAPTER 18 – AIR POLLUTION AND OZONE DEPLETION
18.1 What is the nature of the atmosphere?
The two innermost layers of the atmosphere are the troposphere, which supports life, and the
stratosphere, which contains the protective ozone layer.
Life exists under a thin blanket of gases surrounding the earth, the atmosphere. Divided into several
spheric layers.
Density: the number of gas molecules per unit of air volume.
Atmospheric pressure: the force, or mass, per unit area of a column of air.
About 75-80% of the earth’s air mass is found in the troposphere, the atmospheric layer closest to
the earth’s surface.
Several gases in the troposphere, including H₂O, CO₂, CH₄ and N₂O are called greenhouse gases
because they absorb and release energy that warms the troposphere.
The earth’s second layer stratosphere.
Most of the earth’s ozone is concentrated in a portion of the stratosphere called the ozone layer.
3 O₂ + UV 2 O₃
18.2 What are the major outdoor air polluti on problems?
Pollutants mix in the air to form harmful industrial smog, caused mostly by the burning of coal and
photochemical smog, caused by emissions from motor vehicles, industrial facilities and power plants.
Air pollution is the presence of chemicals in the atmosphere in concentrations high enough to harm
organisms, ecosystems or human-made materials, or to alter climate.
Natural sources of air pollution:
- Wind-blown dust
- Solid and gaseous pollutants from wildfires and volcanic eruptions
- Volatile organic chemicals released by some plants
Most human inputs of outdoor air pollutants occur in industrialized and urban areas where people,
cars and factories are concentrated.
Primary pollutants are chemicals or substances emitted directly into the air from natural processes
and human activities at concentrations high enough to cause harm.
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,In the atmosphere, some primary pollutants react with one another and with other natural
components of air to form new harmful chemicals, called secondary pollutants.
Prolonged high exposure to air pollutants overloads the body’s natural defense mechanisms. Fine
and ultrafine particles can get lodged deep in the lungs and contribute to cancer, asthma, heart
attack and stroke.
Chemical reactions that form major air pollutants:
Pollutant Chemical reaction
Carbon monoxide (CO) 2 C + O₂ 2 CO
Carbon dioxide (CO₂) C + O₂ CO₂
Nitric oxide (NO) N₂ + O₂ 2 NO
Nitrogen dioxide (NO₂) 2 NO + O₂ 2 NO₂
Sulfur dioxide (SO₂) S + O₂ SO₂
Carbon oxides:
- Carbon monoxide: a colorless, odorless and highly toxic gas that forms during the incomplete
combustion of carbon-containing materials.
- Carbon dioxide: colorless, odorless gas.
Nitrogen oxides and nitric acid:
- Nitric oxide: a colorless gas that forms when nitrogen and oxygen gases react under high
temperatures in automobile engines and coal-burning power and industrial plants.
- Nitrogen dioxide: a reddish-brown gas.
- Nitric acid: HNO₃
- NO and NO₂ play a role in the photochemical smog a mixture of chemicals formed under the
influence of sunlight in cities with heavy traffic.
Sulfur dioxide and sulfuric acid:
- Sulfur dioxide: a colorless gas with an irritating odor.
- Aerosols consist of microscopic suspended droplets of sulfuric acid (H₂SO₄) and suspended
particles of sulfate (SO₄²⁻) salts that return to the earth as a component of acid deposition.
Particulates:
- Suspended particulate matter (SPM): consists of a variety of solid particles and liquid droplets
that are small and light enough to remain suspended in the air for long periods.
Ozone:
- Ozone: a colorless and highly reactive gas.
- Extensive measurements indicate that human activities have decreased the amount of
beneficial ozone in the stratosphere and increased the amount of harmful ground-level
ozone.
Volatile organic compounds (VOCs):
- Organic compounds that exist as gases in the atmosphere or that evaporate from sources on
the earth’s surface into the atmosphere are called volatile organic compounds.
Industrial smog: consisting mostly of an unhealthy mix of sulfur dioxide, suspended droplets of
sulfuric acid and a variety of suspended solid particles in outside air.
Photochemical smog is a mixture of primary and secondary pollutants formed under the influence
of UV radiation from the sun.
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,VOCs + NOx + heat + sunlight ground-level ozone + other photochemical oxidants + aldehydes +
other secondary pollutany
Natural factors that help reduce the outdoor air pollution:
- Gravity causes particles heavier than air to settle out
- Rain and snow partially cleanse the air of pollutants
- Salty sea spray from the oceans washes out many pollutants from air that flows from land
over the oceans
- Winds sweep pollutants away and dilute them by mixing them with cleaner air
- Natural chemical reactions remove some pollutants.
Factors that increase outdoor air pollution:
- Urban buildings slow wind speed and reduce the dilution and removal of pollutants
- Hills and mountains reduce the flow of air in valleys below them and allow pollutant levels to
build up at ground level
- High temperatures promote the chemical reactions leading to the formation of
photochemical smog
- Emissions of volatile organic compounds from certain trees and plants in urban areas can
promote the formation of photochemical smog.
- Grasshopper effect: when air pollutants are transported at high altitudes by evaporation and
winds from tropical and temperate areas to the earth’s polar areas as part of the earth’s
global air circulation system.
- The vertical movement of air. Under certain atmospheric conditions, a layer of warm air can
temporarily lie atop a layer of cooler air nearer the ground temperate inversion.
18.3 What is acid depositi on and why is it a problem?
Acid deposition is caused mainly by coal-burning power plants and motor vehicle emissions, and in
some regions, it threatens human health, aquatic life and ecosystems, forests and human-built
structures.
Wet deposition: consisting of acidic rain, snow, fog and cloud vapor, with a pH of less than 5.6.
Dry deposition: consisting of acidic particles.
Resulting mixture: acid deposition/acid rain.
Acid deposition is the result of human activities that disrupt the natural nitrogen cycle and sulfur
chemical cycle by adding excessive amounts of NO x and SO₂ to the atmosphere.
In some areas, soils contain basic compounds such as calcium carbonate (CaCO₃) or limestone that
can react with and help neutralize or buffer some inputs of acids.
Harmful effects of acid deposition:
- Damages statues and buildings
- Contributes to human respiratory diseases
- Harms aquatic ecosystems
- Can harm crops and reduce plant productivity
- Leaching essential plant nutrients such as calcium and magnesium from forest soils.
- Releasing ions of aluminum, lead, cadmium and mercury from forest soils.
Acid deposition:
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, Prevention Cleanup
Reduce coal use and burn only low-sulfur coal Add lime to neutralize acidified lakes
Use natural gas and renewable energy Add phosphate fertilizer to neutralize acidified
resources in place of coal lakes
Remove SO₂ and NOx from smokestack gases Add lime to neutralize acidified soils
and remove NOx from motor vehicular exhaust
Tax SO₂ emissions
18.4 What are the major indoor air polluti on problems?
The most threatening indoor air pollutants are smoke and soot from the burning of wood and coal in
cooking fires (mostly in less-developed countries), cigarette smoke, and chemicals used in building
materials and cleaning products.
Most dangerous indoor air pollutants:
- Tobacco smoke
- Formaldehyde emitted from many building materials and various household products
- Radioactive radon-222 gas, which can seep into houses from underground rock deposits.
Formaldehyde (CH2O)is a colorless, extremely irritating chemical that is considered a carcinogen.
Common sources of indoor air pollution:
- Pesticide residues in the 75% of US homes where pesticides are used indoors at least once a
year.
- Lead particles brought indoors on shoes and collecting in carpets and furnishings.
- Dust mites and cockroach droppings found in some homes, thought to play a role in asthma
attacks.
- Airborne spores of molds and mildew that can cause headaches, allergic reactions and
asthma attacks.
- Candles, almost all of which emit fine-particle soot when burned.
- Clothes dryer sheets that emit ammonium salt, linked to asthma.
- Gas stoves that emit nitrogen dioxide.
- Cleaning products that contain alcohol, chlorine, ammonia and VOCs.
- Air fresheners that emit glycol ethers, which can contribute to fatigue, nausea and anemia.
- Air purifiers that emit ozone.
Sick-building syndrome = various air pollutants found in buildings are linked to a number of health
effects.
18.5 What are the health eff ects of air polluti on?
Air pollution can contribute to asthma, chronic bronchitis, emphysema, lung cancer, heart attack and
stroke.
Your respiratory system helps to protect you from air pollution in various ways.
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