Air Pollution - Polk County School District · 2018-08-30 · oOzone RHS Environmental Science 18 ....

Air Pollution Environmental Science

Mr. Moss

RHS

RHS Environmental Science 2

Definition • Air Pollution – is the presence of chemicals in the

troposphere in concentrations high enough to harm

organisms, ecosystems, or materials, and high

enough to alter climate.

• Can range from annoying to lethal.


Sources • Come from both natural and human sources.

• Natural sources: o Dust (windstorms)

o Wildfires

o Volcanic eruptions

o Volatile Organic Chemicals (VOC’s)

• Released from some plants

• Human sources: o Most are in industrialized and urban areas.

• High concentration of people, factories, and cars.

o Most come from the burning of fossil fuels in

• Power plants and factories (stationary sources)

• Motor vehicles (mobile sources).


Refining the Definition • Pollution is something produced by humans that

interferes with our well-being.

• Although natural source fit our definition, they are

generally not controlled by humans. We will focus

on those factors that are controlled by humans.


Outdoor Pollutants • Two main categories;

o Primary Pollutants

• Emitted directly into the air.

o Secondary Pollutants

• Primary pollutants that react with components of air to form new

harmful pollutants.


Fig. 19-3, p. 442

Primary Pollutants

CO CO2 Secondary Pollutants

SO2 NO NO2

Most hydrocarbons SO3

Most suspended particles HNO3

H2O2 O3 PANs

Most NO3– and SO4

2– salts

Sources Natural Stationary

Mobile

H3SO4

Sources of Primary Pollutants

Pollutant Sources

Carbon Monoxide Incomplete burning of fossil fuels

Tobacco smoke

Hydrocarbons Incomplete burning of fossil fuels

Tobacco smoke

Chemicals

Particulates Burning fossil fuels

Farming operations

Construction operations

Industrial wastes

Building demolition

Sulfur Dioxide Burning fossil fuels

Smelting ore

Nitrogen Compounds Burning fossil fuels 9

Question • How does your daily lifestyle produce some of each

of the primary air pollutants shown in the previous

slide?


News Good Bad


• Over the past 30 years,

outdoor air quality in

most developed

countries has

improved.

• Passage of air pollution

laws.

• WHO estimates 1 out of

6 people on the earth

(1.1 billion) lives in

urban areas. o Poor air quality

• Most live in developing

countries.

• Major threat is from

indoor air pollution. o Heating and cooking

The Relationship • The problem of air pollution is directly related to the

size of the population living in an area and their

activities.

• If population is small and energy use is low, impact

is small. o Pollution is diluted and negative effect is slight.

• In urbanized, industrialized civilizations where use of

fossil fuels is high, we release large amounts of

pollution into the environment.


Relationship • The released particles are mixed and diluted but

stay near the earth due to gravity. o We don’t get rid of it. We just dilute it and move it out of the immediate

area.

• In urbanized, industrialized areas, these particles do

not have time to dilute before reaching another

city. o This magnifies and adds to the problem.



As an air mass moves across from west to east, each population adds to the total load in the atmosphere.

Health Risks • Pollution is not only ugly

to look at, it poses a

health risk. Especially

to: o Respiratory illness patients

o The elderly

o The very young

• Bronchial inflammation

• Allergic Reactions

• Irritations of mucous

membranes


Donora • City in Pennsylvania

• October 1948

• Pollution from a zinc plant

and steel mills became

trapped in a valley

forming a dense smog.

• Within 5 days, o 17 people died

o 5,910 persons became ill

• Affected almost 50% of

the city’s 12,300

population.


Megacities • What do Beijing, Seoul, Mexico City, and Cairo have

in common? o All are megacities in a developing world that have extremely poor air

quality.

• Each also exceed the W.H.O. guidelines for air

quality for at least two pollutants. o Air quality in Mexico City contributes to approximately 6,400 deaths each

year.

• Death rates increase and general health of

population is lowered.


Major Air Pollutants • These include:

oCarbon Oxides

oNitrogen Oxides

o Sulfur Oxides

o Suspended Particulate Matter

oVolatile Organic Compounds

oOzone


Carbon Oxides • The two main oxides of carbon that we will focus on

are:

o Carbon monoxide

o Carbon dioxide


Carbon monoxide (CO) • Odorless, colorless, highly toxic gas.

• Forms from incomplete combustion of carbon-

containing materials. o 2C + O2 2CO

• Major sources o Motor Vehicle Exhaust

o Tobacco smoke

o Clearing and burning of forests/grasslands

o Open fire cooking and inefficient stoves


Health Risks of CO • Reacts with hemoglobin in red blood cells.

o A protein in RBC that carries oxygen.

• Reduces ability of blood to transport oxygen.

• Chronic exposure can trigger o Heart attacks

o Aggravate lung diseases

• Asthma

• Bronchitis

• Emphysema

• High levels cause headaches, nausea, drowsiness, mental impairment, collapse, coma, and death.

• Several hours of exposure to 0.001% concentration can cause death.


Whatchathinkboutit? • The two major sources are motor vehicle exhaust

and tobacco smoke.

• Knowing the health implications, put yourself on any

of the interstates around Atlanta, GA, on a warm

day, between the hours of 4:00 p.m. and 6:00 p.m..

• Discuss with your group any potential problems with

driver alertness. List your answers on paper and be

prepared to share with the class.

• 5 Minutes to discuss


Effects of CO on Driver • The amount of CO produced in heavy traffic can

cause headaches, drowsiness, and blurred vision.

• A heavy smoker in traffic is doubly exposed and

may experience severely impaired reaction time

compared to nonsmoking drivers.


Good News • CO is not a persistent pollutant.

• Natural processes convert CO to other non-harmful

compounds.


Carbon dioxide (CO2) • A colorless, odorless gas.

• About 93% of CO2 in the troposphere is the result of

the natural carbon cycle.

• Remaining 7% results from human activities. o Burning fossil fuels

o Clearing forests/grasslands

• Not regulated by the U.S. Clean Air Act o Deep-pocket lobbyist.


Nitrogen Oxides • Nitrogen Oxide (NO) is a colorless gas.

o Reaction of Nitrogen and Oxygen in high-temp combustion.

o N2 + O2 2NO

• Nitrogen dioxide (NO2) reacts with water in the

atmosphere to form: o Nitric acid (HNO3)

o Nitrate salts (NO3-)

• Plays a role in the formation of photochemical

smog.

• Nitrous oxide (N2O) is a greenhouse gas emitted

from fertilizers, animal wastes, and burning fossil fuels


Sulfur Oxides • Sulfur dioxide (SO2) is a colorless gas with a bad

odor.

• 1/3 of the amount in troposphere comes from

natural sources. 2/3’s come from human sources. o Use of coal to produce electricity, oil refining, smelting

• Can react with water vapor to form sulfuric acid

(H2SO4) and sulfate salts (SO42-). These can lead to

acid deposition.

• Aggravate respiratory problems, corrode metals,

damage paint, paper, leather, and stone.


SPM • Suspended Particulate Matter – solid particles and

liquid droplets small and light enough to stay suspended in the air for short to long periods of time.

• 62% comes from natural sources. o Dust, Wildfires, sea salt nuclei

• 38% from human sources o Plowing fields, road construction, unpaved roads, tobacco smoke, coal-

burning industrial plants, motor vehicles

• Fine SPM (PM-10) is ≤ 10 microns

• Ultrafine SPM (PM-2.5) is ≤ 2.5 microns

• Results in approximately 60,000 premature deaths per year in the U.S.


Ozone • O3

• O2 + UV light + O O3

• Colorless and highly reactive gas

• Good in stratosphere but bad in troposphere

• Major component of photochemical smog.

• Can cause and aggravate respiratory problems.


VOCs • Volatile Organic Compounds- organic compounds

that exist as gases in the air.

• Mostly hydrocarbons such as isoprene (C3H8) and

terpenes (C10H15) that are emitted by plant leaves,

and methane (CH4).

• 1/3 of methane emission are natural (plants,

wetlands, and termites)

• 2/3’s of methane is from human sources (rice

paddies, landfills, oil and gas wells, cow farts)

• Others include benzene, vinyl chloride, and

trichlorethylene.


Radon (Rn) • #86 on Periodic Table; one of the Nobel Gases

• Radioactive gas found in some types of rock and

soils.

• Seeps into homes and buildings that are situated

above the source.

• Has been linked to lung cancer.


Photochemical Smog • A chemical reaction that is activated by light.

• A mixture of primary and secondary pollutant in the

presence of UV radiation

• VOC’s + Nox + heat + UV photochemical smog o Mixture of Ozone, nitric acid, aldehydes, peroxyacl nitrates and other

secondary pollutants

• Hotter days lead to increased levels of ozone and

other components. As traffic increases, smog

increases.


5 Factors Reducing Air Pollution

• Heavier particles settle out due to gravity.

• Precipitation helps to clean the air of pollutants

• Salty sea spray can wash out PM and soluble

pollutants

• Winds carry pollutants away and help dilute by

mixing actions

• Chemical reactions in the atmosphere


6 Factors Increasing Air Pollution

• Buildings can reduce wind speed causing less

dilution

• Surrounding hills and mountains can reduce air flow

to valleys

• Higher temperatures promote chemical reactions

to form photochemical smog

• VOC emissions from certain trees and plants (some

oaks, sweet gums, poplars, and kudzu)

• Grasshopper effect- pollutants are transported from

tropics toward poles.

• Temperature inversions


Acid Deposition • a.k.a. Acid Rain

• Industrial smokestacks can input SOx and NOx above the inversion

• Reduces local but increases regional pollution

• These pollutants may travel over 600 miles (1000 m) o Along the way, they form secondary pollutants from the chemical reactions

with the water vapor

• Descend in two forms o Wet deposition

• pH less than 5.6

• rain, snow, fog, cloud vapor

• 4 – 14 days

o Dry depostion

• acidic particles

• 2 -3 days


Acid Deposition • Regional issue from coal-fired plants and areas with

many cars.

• Eastern U.S. precipitation is about pH 4.4 – 4.7 o 10x greater than normal rain which has a pH of 5.6

• Mountains in Eastern U.S. and those east of Los

Angeles have fog and dew with a pH of 2.3 o this is more acidic than lemon juice

o 1000 times greater than normal rain


Acid Deposition • In soil, some compounds such as limestone (CaCO3)

can react with the acid to help neutralize it. o This is known as Buffering

• On mountains, there is a thin soil layer so the

buffering is minimal

• Some areas have received so much deposition that

the soil is unable to buffer the acids.


Effects of Acid Deposition • Contributes to respiratory illnesses

• Leaching of toxic metals into water supplies o Biomagnification of Hg

• Building and Monument damage

• Car finishes

• Increase of acidity in aquatic ecosystems

• Farms and cropland


Air Pollution - Polk County School District · 2018-08-30 · oOzone RHS Environmental Science 18 ....

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Transcript of Air Pollution - Polk County School District · 2018-08-30 · oOzone RHS Environmental Science 18 ....