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Atmospheric Changes:

Climate Change and Air Pollution Atmosphere is the thin layer of gases that surrounds the Earth

It supports life:

Absorbs dangerous solar radiation

Burns incoming meteors

Transports and recycles water and other chemicals

Drives Climate and Weather

Chemical Composition of Atmosphere

Major components

Minor variable components

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Although the atmosphere’s molecular

composition is largely similar

Certain characteristics change with altitude

Atmosphere is divided in layers

Ozone’s Distribution in the Atmosphere

Ozone layer

Temperature and other characteristics vary

between layers

Stratosphere:

most ozone (0.00004%) found here

ozone layer: filters UV rays

Troposphere:

ozone from human activities

causes health problems

Tropopause:

cap that prevents mixing between layers

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Addressing the problem of Air Pollution

In 1971 the newly-formed Environmental

Protection Agency regulated 6 “criteria”

pollutants…

…even though no conclusive evidence

proved a cause/effect relationship

between the pollutants and human health.

What are the six criteria pollutants in

Air Pollution?

-particulate matter (particles or droplets)

and 5 chemicals:

-sulfur oxides

-carbon monoxide

-nitrogen oxides

-ground-level ozone

-lead

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Addressing the problem of Air Pollution

In 1971, The EPA was following the

Precautionary, Though you are not 100% sure of what is causing a

problem, there is a big risk to “doing nothing.”

All six pollutants have since been shown

to be harmful.

The EPA now lists another 187 hazardous

air pollutants—including carbon dioxide!

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Types of substances and their sources

Gases:

Oxides of carbon (CO, CO2)

Oxides of nitrogen (N2O, NOx)

Oxides of Sulfur (SO2)

VOC Tropospheric Ozone

Ozone depleting substances (ODS)

Aerosols:

Particulate matter (soot, dust and smoke)

Metals (lead and mercury)

Transformation: Pollution Changes in the air

Primary pollutants Secondary Pollutants

Emitted directly Form in the air

from source from primary pollutants

Note: Some chemicals can be considered primary and secondary

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Impact of Air Pollutants • Change in Temperature:

Global warming (CO2 CH3 , HCFCs and N2O)

• Change in Water acidity:

Acid precipitation (SO2 and NOx)

• Depletion of stratospheric ozone:

ODP (chemicals with Bromide or Chloride atoms)

• Health problems:

Industrial smog SO, CO

Photochemical smog NO2 and VOC (volatile organic compounds)

Lead and Mercury

(deposited in water, enter food chain, accumulate in tissue)

Industrial Smog or Gray Smog

Cause: combustion of coal and diesel

Chemistry:

Incomplete combustion soot

Reaction of sulfur with

other elements in air sulfur compounds

Products: Sulfur compounds and soot

Impact:

irritate respiratory tract

impair breathing

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Industrial smog in

London 1952

Picture taken at mid-day

Industrial smog in

Pennsylvania in 1948

Killing about 12000 people

Photochemical Smog or

Brown smog

Cause: gasoline combustion

on hot sunny days

Chemistry:

Reaction of light with NO2 and VOC’s

Products: Ozone and 100 more

Impact:

reduces photosynthesis

affects human health

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Topography and Climate in LA favors

photochemical smog conditions Thermal inversion

The warm air holds down the cool air and

prevents pollutants from rising and scattering.

What are the health impacts to Los angelinos?

Stratospheric Ozone depletion

Cause: ODS (ozone depleting substances)

CFCs, its substitutes HCFCs, Halons

Methyl bromide (pesticide of strawberries)

ODS vary in

their in their life times and potential

Compare Halons with CFCs

Chemistry:

UV rays free Cl or Br atom

This atom destroys O3

Into O2 and O

Result:

Ozone layer gets thinner

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Impact of O3 depletion

International treaty for ODS 1987 Montreal Protocol

signed by 180 countries

Stop production of CFCs

Reasons for success of the Montreal Protocol:

- Government and industry cooperated on finding solutions

- Cheap replacement technologies

Future amendments have not been

as successful

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Issues to consider • Illegal trade of CFC on the raise

• A large number of used CFC-based refrigerators are being exported to developing countries by countries that have phased out CFCs.

• Atmospheric halons continue to increase (production ended in 1994)

Halons in existing fire-fighting equipment emitted whenever there is a fire

Concern:

bromide in Halons is 50 x more potent than CFCs

• Countries had promised to phase out methyl bromide 100% by 2005

Nov 2006, meeting agreed to allow US to produce of more pesticide

even though their stock piles have enough for farmers needs

Farmers allowed = 8,900 tons,

US stockpiles = 11,000 tons,

Allowed new production = 7,600 tons.

• New estimates:

Ozone layer in mid latitudes will not return to pre-1980 levels until 2049

Antarctic ozone will only return around 2065

This year's Antarctic ozone "hole" was the largest ever recorded.

• CFCs are being replaced by HCFCs, which have a large global warming potential.

Present and future

ozone levels

2011 2075 2050

Largest ozone

“hole” ever

recorded

above the

Arctic!

Mid-latitude

areas back to

pre-1980

ozone levels

Polar regions

back to

pre-1980

ozone levels

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Questions

• Is the depletion of the ozone layer over?

• Why are we concerned about the ozone layer?

• What are the differences between industrial

smog and photochemical smog?

Acid Rain Cause:

Combustion of fossil fuels

Chemistry:

SO2 and NO reacts with water, oxygen, and oxidants Nitric and Sulfuric acids

Result:

Acids can remain in atmosphere

They can be transported long distances

Eventually these fall as rain or snow

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Acid Rain Impact Acid rain on soil

leaches basic minerals (calcium and magnesium)

no longer available to plants us

Acid rain on lakes or rivers

increase acidity of water

harm fauna

Acid rain or fog on forests

damage plant tissue

Acid rain on buildings

eats away concrete

Why should air pollution be regulated

federally and internationally? Not just locally

Green House gases

ODS

Acids

Tropospheric ozone

They are transboundary problems

cross political borders

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Emissions reduction: Electricity

At the Industry level:

Improved technology at plants

Expansion of alternative sources

of energy

At the Consumer level:

Energy saving habits

Product choices

Emissions reduction: Transportation

At the Industry level:

Improve efficiency of cars

Improve exhaustion quality

At the Consumer level:

Consumer choices

Consumer habits

Walking briskly for just 2 miles

every day or cycling for five can

reduce your chances of heart

disease by 1/2