APES Unit 7: Atmospheric Pollution

How is photochemical smog formed?

Photochemical smog is formed when sunlight reacts with the primary pollutants nitrogen oxides (NOx) and VOCs emitted by cars and factories; This creates a mixture of harmful secondary pollutants such as tropospheric ozone, PANs, and aldehydes; Heat and intense UV radiation increase smog formation

Health effects of photochemical smog

* Nose and throat irritation
* lung inflammation
* scar lung tissue (fibrosis)
* worsened asthma

Solutions to reduce photochemical smog

* Catalytic converters
* vapor recovery nozzles
* reduce vehicle use

How is tropospheric ozone formed?

NOx + VOCs + sunlight → O3 (much worse in the summer due to more heat/sunlight)

Health effects of tropospheric ozone

* Chest pain
* coughing
* throat irritation
* bronchitis
* asthma
* scar lung tissue (fibrosis)

Environmental effects of ozone

Interferes with the ability of sensitive plants to produce and store food, harms plant appearance, degrades rubber,

Acid deposition

Acidic substances or acid-forming substances that fall to Earth (materials may be wet or dry)

Secondary pollutants of acid deposition

Sulfuric and nitric acid

Nitric oxides that cause acid deposition come from…

motor vehicles and coal-burning power plants

Sulfur dioxides that cause acid deposition come from…

coal-burning plants

How is acid deposition formed?

Acid deposition forms when gaseous sulfur dioxide and nitric oxides are released into the atmosphere and react with oxygen and water to form sulfuric/nitric acid

Effects of acid deposition

* Damages leaves and bark, impairing photosynthesis and increasing vulnerability to disease
* Leaches (takes away) calcium and magnesium from soil, depriving trees of essential minerals
* Acid reaction with soil minerals releases toxic aluminum ions
* Wet depositions erodes human-made structures
* Increases pH and level of heavy metals in aquatic environments which harms species
* Eutrophication from increased nitrates

Thermal inversion

When the normal temperature gradient in the atmosphere is changed as cool air gets trapped under a layer of hot air

Effects of thermal inversions

Air pollution is trapped close to the ground, especially smog and particulates because they can’t rise

Concentrations of these pollutants peak in the mid-morning from vehicle exhaust

VOCs and NOx

Concentration of this secondary pollutant peaks in the afternoon due to increased sunlight

Tropospheric ozone

Air pollution

Anything in the atmosphere that is harmful to humans or the environment

Primary pollutants

Emitted directly into the atmosphere

Natural: pollen, volcanic ash, VOCs given off by plants

Anthropogenic: products of combustion of fossil fuels (CO2, NOx, SO2)

Secondary polluants

Form once they are in the atmosphere, usually by combining with water vapor or other atmospheric gases (tropospheric ozone, acid rain)

Criteria pollutants of the Clean Air Act

* Sulfur dioxide (SO2)
* Particulate matter (PM)
* Lead (Pb)
* Ozone (O3)
* Nitrogen dioxide (NO2)
* Carbon monoxide (CO)

SPLONC

Low-level lead exposure health impacts

Children

* Anemia
* Behavioral disorders
* Lowered IQ
* Reading and learning disabilities
* Nerve damage

Adults

* Hypertension
* Cardiovascular disease

Air quality can be affected through the release of sulfur dioxide during the burning of fossil fuels, mainly…

diesel fuels

Sulfur is present in larger quantities in…

marine fossil fuels

Coal combustion releases air pollutants including…

carbon dioxide, sulfur dioxide, toxic metals, and particulates

Effects of fossil fuel pollution

* Inhaled pollutants exacerbate existing lung conditions and can cause permanent lung damage
* Can damage plant tissue during photosynthesis and respiration

NOx + VOCs + UV + heat =

O3 + PANs

VOCs

Pollutants which vaporize at room temperatures and have an increased presence in the atmosphere (antropo: formaldehyde, gasoline; natural: trees, plant oils)

Ozone levels are higher in…

sunny, warm climates

Catalytic converters

* Convert NO into O2 and N2
* CO and hydrocarbons react to produce CO2 and H20

Vapor Recovery Nozzles

Prevent the release of VOCs into the atmosphere from gas

Geography that encourages inversion layers

* Valleys
* Nearby mountains
* Coastal or prevailing winds

CO2 appears naturally in the atmosphere from sources such as…

respiration, decomposition, and volcanic eruptions

PM10

* Between 2.5 and 10 microns (larger particle size)
* **Upper respiratory concern because they can be stopped**

PM2.5

* Under 2.5 microns
* Lower respiratory concerns and can enter blood stream due to small size

Natural sources of PM

* Pollen
* Spores
* Bacteria
* Dust
* Airborne soil
* Sea salt
* Volcanic dust

Health effects of PM

* Eye irritation
* Pneumonia
* Respiratory irritation

Common natural source indoor air pollutants

* Radon
* Mold
* Dust

Indoor air pollutants that are classified as particulates

* Asbestos
* Dust
* Smoke

Radon-222

A naturally occurring radioactive gas that is produced by the uranium found in rocks and soils and can seep into houses through cracks

Asbestos causes the disease…

mesothelioma

Carbon monoxide is an indoor air pollutant that is classified as an…

asphyxiant

Health effects of CO

* Impairs the ability of red blood cells to carry oxygen through your body. Reacts with hemoglobin to create a molecule which can’t carry oxygen.
* Dizziness, nausea, and suffocation

Exposure to radon gas can lead to…

radon-induced lung cancer, which is the second leading cause of lung cancer in America

Methods to reduce air pollutants include…

regulatory practices, conservation practices, and alternative fuels

The Clean Air Act supports the development of alternative fuel for transportation. These fuels reduce pollutants in emissions:

* Natural gas
* Propane
* Ethanol
* Electricity
* Biofuels

Catalytic converters use…

high temperatures and chemical rxns to change air pollutants from fuel combustion into less toxic gases exiting tail pipes

Methods to reduce air pollution from **coal-burning power plants** include…

scrubbers and electrostatic precipitators

Wet and dry scrubbers are air pollution control devices that remove…

particulates and/or gases from industrial exhaust streams

Wet scrubbers

* Use a spray or mist to capture or change pollutants
* For sulfur oxides, the liquid is often a combination of limestone powder and water that makes a slurry

Dry scrubbers

* Use dry particles, or reagents, to capture or change pollutants
* Due to the added weight, the particulates will fall to the bottom of the chamber and be collected

What’s more effective, dry or wet scrubbers?

Wet scrubbers

Electrostatic precipitators

* force gas through a chamber that adds a charge to the pollutants
* As soot particles move past metal plates or filters that have an opposite charge, the particles stick their
* Clean air can leave chamber
* These devices can be used as the first step before the gases move into a scrubber chamber

All 3 technologies are effective, but…

they create waste (sludge or toxic fly ash), which must be disposed of and can cause issues (ash slides)

Electrostatic precipitators use electrical charge attractions to remove…

particles from exhaust stream of coal-fired plants

Acid deposition mainly affects communities that are…

downwind from coal-burning power plants

Regional differences in soils and bedrock affect the impact that acid deposition has on the region, such as…

limestone bedrock’s ability to neutralize the effect of acid rain on lakes and ponds

How does acid deposition cause calcium deficiencies

Acid deposition promotes aluminum ions to leach from soils, which prevent the uptake of calcium in tree roots. Calcium is critical for normal cell processes.

Effects of noise pollution

* Stress
* Masking sounds used to communicate or hunt
* Damaged hearing
* Changes to migratory routes