Ozone DepletionOzone Depletion

Significant concentrations of ozone (OSignificant concentrations of ozone (O33) exist in the lower ) exist in the lower

elevations of the stratosphere. elevations of the stratosphere.

Ozone in the stratosphere Ozone in the stratosphere absorbs UV B radiation from absorbs UV B radiation from sunlight.sunlight.

UV B radiation damages UV B radiation damages DNA molecules and can DNA molecules and can cause genetic defects on the cause genetic defects on the outer surfaces of plants and outer surfaces of plants and animals, including human animals, including human skin (skin cancer)skin (skin cancer)

Ozone Depletion ResultsOzone Depletion Results

Each 1% loss of ozone leads to a 2% increase in UV radiation Each 1% loss of ozone leads to a 2% increase in UV radiation striking the earth.striking the earth.

A 2% increase in UV radiation results in a 5% to 7% A 2% increase in UV radiation results in a 5% to 7% increase in skin cancer, including a 1% increase in deadly increase in skin cancer, including a 1% increase in deadly malignant melanomamalignant melanoma

A 5% Ozone Depletion would cause:A 5% Ozone Depletion would cause:

An additional 940,000 cases annually of basal-cell and squamous-cell An additional 940,000 cases annually of basal-cell and squamous-cell skin cancer (disfiguring, but not usually deadly)skin cancer (disfiguring, but not usually deadly)

An additional 30,000 cases annually of melanoma skin cancer (often fatal). An additional 30,000 cases annually of melanoma skin cancer (often fatal). There are 9,000 American deaths per year from this now. There are 9,000 American deaths per year from this now.

A sharp increase in eye cataracts and severe sunburn in people, A sharp increase in eye cataracts and severe sunburn in people, cataracts in cattle.cataracts in cattle.

Suppression of the human immune systemSuppression of the human immune system

An increase in smog. The EPA estimates a 1% decrease in stratospheric An increase in smog. The EPA estimates a 1% decrease in stratospheric ozone causes a 2% increase in ozone near the groundozone causes a 2% increase in ozone near the ground

Reduced yields from crops like corn, rice, beans, and wheatReduced yields from crops like corn, rice, beans, and wheat

Reduction in ocean phytoplankton growthReduction in ocean phytoplankton growth

Loss of $2 billion per year from materials degradationLoss of $2 billion per year from materials degradation

Increased global warmingIncreased global warming

Causes of DepletionCauses of Depletion

Chlorine and Bromine in the StratosphereChlorine and Bromine in the Stratosphere

CFC-11 (chlorofluoromethane) and CFC-12 CFC-11 (chlorofluoromethane) and CFC-12 (dichlorofluoromethane) are the most widely used as (dichlorofluoromethane) are the most widely used as coolants for refrigerators and air conditionerscoolants for refrigerators and air conditioners

CFC-11 (chlorofluoromethane) and CFC-12 CFC-11 (chlorofluoromethane) and CFC-12 (dichlorofluoromethane) are the most widely used as (dichlorofluoromethane) are the most widely used as coolants for refrigerators and air conditionerscoolants for refrigerators and air conditioners

SourcesSources

Chlorofluorocarbons (CFC’s)Chlorofluorocarbons (CFC’s)Commonly called Freons (a Du Pont Chemical tradename)Commonly called Freons (a Du Pont Chemical tradename)

Also used as propellant in aerosol cans, industrial cleaner, hospital Also used as propellant in aerosol cans, industrial cleaner, hospital sterilant, fumigant, and to create bubbles in polystyrene plastic foam sterilant, fumigant, and to create bubbles in polystyrene plastic foam used for insulation and packaging.used for insulation and packaging.

HalonsHalonsBromine containing compounds used in fire extinguishersBromine containing compounds used in fire extinguishers

Carbon TetrachlorideCarbon TetrachlorideAn industrial solventAn industrial solvent

Methyl ChloroformMethyl ChloroformSolvent, correction fluid, dry cleaning spray, spray adhesiveSolvent, correction fluid, dry cleaning spray, spray adhesive

United States accounts for largest part of world-wide United States accounts for largest part of world-wide consumption o CFC’sconsumption o CFC’s

29% of global consumption is from US29% of global consumption is from US

Americans use six times more CFC’s than global Americans use six times more CFC’s than global averageaverage

Vehicle air conditioners accounted for about 75% of Vehicle air conditioners accounted for about 75% of annual CFC emissions in the US in 1990annual CFC emissions in the US in 1990

Since 1978 the use of CFC’s in aerosol cans has been Since 1978 the use of CFC’s in aerosol cans has been banned in many countries; however, worldwide, banned in many countries; however, worldwide, aerosol cans still account of 25% of CFC emissionsaerosol cans still account of 25% of CFC emissions

What do these compounds do?What do these compounds do?

Spray cans, discarded and/or leaking refrigeration and air conditioning units, Spray cans, discarded and/or leaking refrigeration and air conditioning units, the production and burning of plastic foam products, and the use of solvents the production and burning of plastic foam products, and the use of solvents result in the release of these compounds into the environment.result in the release of these compounds into the environment.

Most of these compounds are non-reactive and have lives of 22 to 111 Most of these compounds are non-reactive and have lives of 22 to 111

years in the atmosphereyears in the atmosphere..

They circulate in the atmosphere until they reach the stratosphere.They circulate in the atmosphere until they reach the stratosphere.

In the stratosphere they are broken down by UV radiation to release In the stratosphere they are broken down by UV radiation to release chlorine and bromine atomschlorine and bromine atoms

Chemical reactions between chlorine or bromine and ozone cause ozone Chemical reactions between chlorine or bromine and ozone cause ozone to degrade to Oto degrade to O22 and O. and O.

Over time a single chlorine atom can cause the breakdown of as many as Over time a single chlorine atom can cause the breakdown of as many as 100,000 molecules of ozone.100,000 molecules of ozone.

The Ozone HoleThe Ozone Hole

In the 1980’s researchers discovered that up to 50% of the ozone in In the 1980’s researchers discovered that up to 50% of the ozone in the stratosphere over Antartica is destroyed between September and the stratosphere over Antartica is destroyed between September and October (Arctic Spring). An area larger than the USOctober (Arctic Spring). An area larger than the US

CauseCauseVortexing winds with ice crystals that have absorbed CFC’s on the surface Vortexing winds with ice crystals that have absorbed CFC’s on the surface that lift CFC’s into the stratosphere and destroy the ozone at a fast rate.that lift CFC’s into the stratosphere and destroy the ozone at a fast rate.

The vortex breaks up in a couple of months and large masses of ozone depleted The vortex breaks up in a couple of months and large masses of ozone depleted air flow northward over parts of Australia, New Zealand and southern South air flow northward over parts of Australia, New Zealand and southern South America. During this time UV levels increase by as much as 20% there.America. During this time UV levels increase by as much as 20% there.

A similar phenomenon has recently been observed in the Arctic regionsA similar phenomenon has recently been observed in the Arctic regions

Satellite photo of south pole. Purple shade shows the extent of the ozone hole.Satellite photo of south pole. Purple shade shows the extent of the ozone hole.

Ozone Depletion ObservationsOzone Depletion Observations

Average drops in Ozone levels between 1969 and 1986Average drops in Ozone levels between 1969 and 1986

Protecting the Ozone LayerProtecting the Ozone Layer

Ban the use of CFC’sBan the use of CFC’s

Have to replace with somethingHave to replace with something

Current replacements are greenhouse gases and do Current replacements are greenhouse gases and do not eliminate ozone depletion, just slow it downnot eliminate ozone depletion, just slow it down

Indoor Air PollutionIndoor Air Pollution

Air Quality StandardsAir Quality Standards

Emission StandardsEmission Standards

Limit amounts of pollutants that can be emitted by pollution sourcesLimit amounts of pollutants that can be emitted by pollution sources

Generally set by State Air Quality OfficesGenerally set by State Air Quality Offices

Ambient Air Quality StandardsAmbient Air Quality Standards

The Clean Air Act, which was last amended in 1990, requires EPA to set National Ambient The Clean Air Act, which was last amended in 1990, requires EPA to set National Ambient Air Quality Standards for pollutants considered harmful to public health and the Air Quality Standards for pollutants considered harmful to public health and the environment. The Clean Air Act established two types of national air quality standards. environment. The Clean Air Act established two types of national air quality standards. Primary standards set limits to protect public health, including the health of "sensitive" Primary standards set limits to protect public health, including the health of "sensitive" populations such as asthmatics, children, and the elderly. Secondary standards set limits to populations such as asthmatics, children, and the elderly. Secondary standards set limits to protect public welfare, including protection against decreased visibility, damage to animals, protect public welfare, including protection against decreased visibility, damage to animals, crops, vegetation, and buildings.crops, vegetation, and buildings.  The EPA Office of Air Quality Planning and Standards (OAQPS) has set National Ambient The EPA Office of Air Quality Planning and Standards (OAQPS) has set National Ambient Air Quality Standards for six principal pollutants, which are called "criteria" pollutants. Air Quality Standards for six principal pollutants, which are called "criteria" pollutants. They are listed below. Units of measure for the standards are parts per million (ppm) by They are listed below. Units of measure for the standards are parts per million (ppm) by volume, milligrams per cubic meter of air (mg/m3), and micrograms per cubic meter of air volume, milligrams per cubic meter of air (mg/m3), and micrograms per cubic meter of air (µg/m3).(µg/m3).

http://www.epa.gov/oar/oaqps/peg_caa/pegcaain.html#indexhttp://www.epa.gov/oar/oaqps/peg_caa/pegcaain.html#index

A guide to the Clean Air Act may be found at the EPA website:A guide to the Clean Air Act may be found at the EPA website: