ap environmental science ch. 18 air pollution

Air Pollution

Ch. 18

Number 1 Threat to Human Health - Air Pollution

Asian Brown Cloud - size of continental US Dust, smoke, ash from clearing and

burning forests for crops Acidic compounds, soot, mercury, lead,

fly ash from burning coal, gas, oil Contributes to 700,000 deaths per year Moves over Pacific to CA Reduced photosynthesis by plants Traps heat near surface - warms the earth

Our Precious Atmosphere Atmosphere - thin layer of gasses divided

into several layers based on temperature

Differences in temperature of layers of the atmosphere

Temp changes rather abrupt

Based on composition of gases and their collective ability to absorb solar radiation

Our Layer - the Troposphere Troposphere - layer closet to

the surface of the Earth 5-11 miles up Made up mostly of nitrogen gas -

N2 - 78% and oxygen gas - O2 - 21%

Rest is water vapor, argon, CO2, dust, soot, methane, ozone, nitrous oxide (N2O)

Troposphere is dynamic - plays key role in biogeochemical cycles, weather, climate

Our Sunscreen - the Stratosphere

Next layer up - 11-30 miles Mostly the same gasses as the

troposphere except MUCH LESS water vapor and MUCH MORE ozone (O3)

Ozone layer blocks about 95% of the incoming solar radiation Protects us from sunburn, skin & eye

cancer, cataracts, immune system damage

Protects the O2 in the troposphere from becoming O3

Let’s go outside!

Outdoor Air Pollution - the presences of chemicals in the atmosphere in high enough concentrations to cause harm to humans or the environment

Sources

Natural - dust, volcanic ash, smoke from wildfires

Human - mostly in industrialized areas from cars, factories

Air Pollution is not new Middle agesMiddle ages - wood is primary fuel

source; very polluting Industrial RevolutionIndustrial Revolution in late 1700s -

burning coal 1850s London1850s London - smog so thick created

sunless winters 1880 - coal smog kills 2200 1911 - coal smog kills 1100 1952 - smog kills 4000-12,000 - during

daytime people couldn’t even see their own feet

1948 US Pennsylvania - killer fog lasted 5 days, sickened half the city and killed 20

1963 NY city - air pollution kills 300

Donora, PA at noon

Mixing it up! Pollutants in the air

can combine to form new, even more harmful chemicals

Wind can move air pollution from it’s source to new areas

Primary Pollutants - harmful chemicals emitted directly to the air

Secondary Pollutants - primary pollutants react with each other and the atmosphere to make new chemicals

Good News and Bad News

Good - air quality has improved a lot since the 1970s due mostly to grassroots efforts by citizens demanding clean air

Bad - There are still over 1 billion people living in areas with unhealthy air (mostly in crowded cities in developing nations)

More Bad News Air Pollution used to be

a local problem Now it is a global

problem High volume of

pollutants from sources all over the planet

Wind blows pollution everywhere - even the arctic where there are no cities

Arctic haze from air pollution in northern Eurasia

Quick Check

1. What is the composition of the atmosphere?

2. What are some sources of air pollution?

3. What are primary and secondary pollutants?

Best to set up notes this wayName of pollutant

Chemical formula

Sources Harmful effects

Other info

1.

2.

3.

4.

5.

6.

7.

8.

9.

Major Outdoor Air PollutantsThe List1. Carbon monoxide (CO)

1. Sources are cars, fires, stoves

2. Reacts with hemoglobin in blood to reduce oxygen flow

3. Chronic exposure - lung disease, asthma, emphysema

4. High levels - headache, nausea, drowsiness, mental impairment, collapse, coma, death

5. Indoor CO detectors

2. Carbon Dioxide (CO2)

- 93% of the CO2 in the air just part of the natural carbon cycle- rest from human activities – burning fossil fuelsCO2 is a greenhouse gas that traps heat near the surface of the earth

3. Sulfur dioxide (SO2)1. Stinky2. ~1/3 just part of natural sulfur

cycle3. 2/3 from human sources - mostly

coal burning, oil refining, smelting4. SO2 + atmosphere = sulfuric acid

(H2SO4) and sulfate salts (SO42-) -->

acid rain5. All three create haze, irritate lungs,

damage crops, trees, soil, pH of lakes, corrode metals, paint, paper, leather, stone

Sulfur creates yellow/brown Sulfur creates yellow/brown smogsmog

1. Nitrogen oxides (NOx)

1. NO and NO2

2. NO comes from cars, power plants, lightning, nitrogen fixing bacteria

3. NO + oxygen = NO2 -reddish brown gas --> photochemical smog

4. NO2 + water vapor = nitric acid (HNO3) and nitrate salts (NO3

-) --> acid rain

5. Nitrous oxide (N2O) from fertilizer, poo, burning fossil fuels - a greenhouse gas

6. Irritates the eyes, nose, throat; aggravates asthmaMarble statue being

corroded by acid rain

1. Suspended particulate matter (SPM)1. Tiny solids and liquid droplets that stay

suspended in the air1. ~2/3 from dust, fires, sea salt

2. ~1/3 from coal burning power plants, cars, plowed fields, unpaved roads, construction, tobacco smoke

2. Fine and ultrafine particles irritate respiratory tract, damage lungs, aggravate asthma

3. Toxic particulates like lead and PCBs cause mutations, reproductive problems, cancer

4. Reduce photosynthesis, alter climate

Oil refinery fire in New Delhi

Ozone – O3

1. Major component of smog2. Secondary pollutant from cars + heat3. Causes coughing, breathing difficulty, heart

and lung disease, reduce resistance to colds, irritate eyes, nose, throat

4. Damages plants, rubber, fabrics, paints5. A greenhouse gas in the troposphere

Lead – Pb Paint, lipstick, leaded gas1. Does not break down in the

environment2. 12,000-16,000 kids under age 9

treated for lead poisoning in US every year (200 die)

3. Symptoms:1. Palsy, partial paralysis, blindness,

mental retardation

4. Low level exposure symptoms: 1. Lowered IQ, shortened attention

span, hyperactivity, hearing loss, behavioral disorders

Sources of lead: Leaded gas (phased out from 1976-1986 in US,

but still used in some countries) Lead paints (phased out in 1970) Toys with lead paint (2007 major recall of

Chinese toys) Lead in lipstick (red, turns black on contact

with gold) Lead pipes

Ozone Depleting Chemicals CFCs- Refrigerants Halons - Fire extinguishers Methyl bromide - Soil fumigants

CFCs- Refrigerants Halons - Fire extinguishers Methyl bromide - Soil fumigants

Cause ozone depletion in the stratosphere

Act as greenhouse gases in the troposphere

Leads to more skin cancers, cataracts

Leads to reduced crop yield, leaf burn

1. Volatile Organic Compounds

Mostly hydrocarbons (CxHx)1. Isoprene (C3H8)

2. Terpenes (C10H15)

3. Methane (CH4)

Some from industrial solvents 1. Benzene, vinyl chloride, TCE from dry cleaning,

plastics, synthetic rubber, paints1. Benzene exposure can cause leukemia, blood disorders,

death

From plants, termites, rice paddies, landfills

Gulf Oil explosion and fire released large amounts of VOCs including benzne

Quick Check

Can you name the 9? How many can you name without looking

at your notes?

Ideas?

1. What kinds of health effects are COMMON to all air pollutants?

2. What kinds of sources are COMMON to most air pollutants?

3. What can we do to reduce air pollution? (come up with at least 3 specific actions)

SMOG Industrial smog (gray

smog) - from coal burning power plants Mostly sulfur dioxide,

sulfuric acid, suspended particles

Many urban areas have pollution control measures to reduce particulates and sulfur

Some countries (China, India, Ukraine) still do not

Chemistry of Industrial Smog

C + O2 CO2 carbon dioxide

2C + O2 2CO carbon monoxide

S + O2 SO2 sulfur dioxide

2SO2 + O2 2SO3 sulfur trioxide

SO3 + H2O H2SO4 Sulfuric acid

2NH3 + H2SO4 (NH4)2SO4 ammonium sulfate

Photochemical smog - (brown smog) Mix of primary and

secondary pollutants + sunlight + heat

Exhaust from cars releases nitrogen oxides and VOCs

Hotter days = more smog Worst in cities with dry,

hot climates and lots of commuters Los Angeles, Denver, Salt

Lake City, Mexico City

N2 + O2 2NO During Combustion

2NO + O2 2NO2 (nitrogen dioxide)

In the troposphere

3NO2 + H2O 2HNO3 + NO (nitric acid)

NO2 + UV radiation NO + O

O2 + O O3 (photochemical ozone)

Chemical Reactions resulting in Photochemical Smog

Hydrocarbons + O2 + NO PANs (peroxyacyl nitrates)

O & O3 + Hydrocarbons aldehydes

Decrease Smog - Increase Smog Decrease:

Gravity Rain and snow Salty sea spray Wind Chemical reactions

Increase: Buildings (slow wind) Hills and mountains (reduce air flow in

valleys) High temps VOCs Grasshopper effect (winds move pollutants to

other areas) Inversion layers (warm air layer prevents

pollutants from dispersing upward)

Acid Deposition Coal burning power plants, smelters, etc

have tall smoke stacks Release pollutants high into air where they can

be diluted and dispersed Reduces local air pollution Increases air pollution downwind (up to 600

miles away)

Pollutants stay in atmosphere for 2-14 days depending on the weather Then fall back to earth in rain, snow, fog,

particles = acid deposition (aka acid rain) pH of less than 5.6

Areas with fairly basic soil (high CaCO3 or limestone) can neutralize the acid precipitation

Areas with acidic soil greatly harmed

Green and red areas of this map

The problems is worst in…

China! (duh) - lots of coal power plants Threatening the food supply of China, Japan,

North Korea, South Korea

Eastern US - acid rain as acidic as lemon juice in some mountain areas

Effects of acid deposition

Buildings, car paint Can leach toxic metals

from soil and rock into lakes Toxins build up in fish

eaten by birds, mammals, people

45 US states have warnings about the high levels of mercury in their fish

Acid deposition harms aquatic ecosystems Reduces pH below tolerance level of fish Leaches aluminum from soil into lakes - chokes

fish to death Many lakes in Norway, Sweden, Canada, US

East have no fish in lakes anymore

Areas most affected

Areas downwind of large car-dominated cities

Thankfully still a minority of the world’s lakes and forests are affected

So what to do? Prevention is best policy -

cheapest, safest But this is political difficult

because People/areas affected far away

from problem source Coal is cheap and plentiful so

there is economic incentive to burn it

Coal power plant owners resist investing in latest pollution control measures because then they would have to increase what they charge consumers

Clean up involves trying to neutralize soils and waters with limestone

Expensive and temporary, since it will just rain again

Not always effective

Quick Check

Should cities downwind of a factory or power plant get to make decisions/regulations for those power plants? (e.g. emission regulations, rules about pollution control devices, etc)

Try to give both sides of the argument. Remember, these cities may be 600 miles

away or more (that’s like from here to Denver, CO)