Air PollutionAir Pollution

Questions for TodayQuestions for Today

1.1. What are the basics we need to What are the basics we need to understand about the atmosphere?understand about the atmosphere?

2.2. What are the two types of pollutants in our What are the two types of pollutants in our Air?Air?

3.3. What are the major Primary Pollutants in What are the major Primary Pollutants in our Air?our Air?

STRUCTURE AND SCIENCE OF STRUCTURE AND SCIENCE OF THE ATMOSPHERETHE ATMOSPHERE

The atmosphere The atmosphere consists of several consists of several layers with different layers with different temperatures, temperatures, pressures, and pressures, and compositions.compositions.

Figure 19-2Figure 19-2

Composition of the AtmosphereComposition of the Atmosphere

Components – Oxygen 21%, Nitrogen Components – Oxygen 21%, Nitrogen 78%78%

Layers – troposphere, stratosphere, Layers – troposphere, stratosphere, mesosphere, thermosphere, exosphere mesosphere, thermosphere, exosphere (extends from 310 miles to (extends from 310 miles to interplanetary space)interplanetary space)

STRUCTURE AND SCIENCE OF STRUCTURE AND SCIENCE OF THE ATMOSPHERETHE ATMOSPHERE

The atmosphere’s innermost layer The atmosphere’s innermost layer (troposphere) is made up mostly of nitrogen (troposphere) is made up mostly of nitrogen and oxygen, with smaller amounts of water and oxygen, with smaller amounts of water vapor and COvapor and CO22..

Ozone in the atmosphere’s second layer Ozone in the atmosphere’s second layer (stratosphere) filters out most of the sun’s (stratosphere) filters out most of the sun’s UV radiation that is harmful to us and most UV radiation that is harmful to us and most other species.other species.

Fig. 19-2, p. 440

Atmospheric pressure (millibars)

Temperature

Thermosphere

Pressure

Mesopause

Heating via ozoneMesosphere

Stratopause

Alt

itu

de

(kil

om

eter

s)

Stratosphere Alt

itu

de

(mil

es)

Tropopause

Ozone “layer”

Heating from the earthHeating from the earthTroposphere

Temperature (˚C)

Pressure = 1,000 millibars at ground level

(Sea level)

Composition of the Atmosphere Composition of the Atmosphere (cont.)(cont.)

Primary Pollutants – methane, ozone, Primary Pollutants – methane, ozone, dust particles, microorganisms, and dust particles, microorganisms, and chlorofluorocarbons (CFC’s)chlorofluorocarbons (CFC’s)

Causes of Primary Pollutants – Causes of Primary Pollutants – factories, factories, cars, wind and soil, volcanoes, cars, wind and soil, volcanoes, forest fires, pollen, decaying plants, salt forest fires, pollen, decaying plants, salt particles from the sea, and refrigerants.particles from the sea, and refrigerants.

AIR POLLUTIONAIR POLLUTION

Some primary air pollutants may react with one another Some primary air pollutants may react with one another or with other chemicals in the air to form secondary air or with other chemicals in the air to form secondary air pollutants.pollutants.

Figure 19-3Figure 19-3

Fig. 19-3, p. 442

Primary Pollutants

CO CO2Secondary 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

Major Air PollutantsMajor Air Pollutants Carbon oxidesCarbon oxides: :

– Carbon monoxide (CO) is a highly toxic gas that Carbon monoxide (CO) is a highly toxic gas that forms during the incomplete combustion of carbon-forms during the incomplete combustion of carbon-containing materials.containing materials.

– 93% of carbon dioxide (CO93% of carbon dioxide (CO22) in the troposphere ) in the troposphere

occurs as a result of the carbon cycle.occurs as a result of the carbon cycle.

– 7% of CO7% of CO22 in the troposphere occurs as a result of in the troposphere occurs as a result of

human activities (mostly burning fossil fuels).human activities (mostly burning fossil fuels). It is not regulated as a pollutant under the U.S. Clean Air It is not regulated as a pollutant under the U.S. Clean Air

ActAct..

Major Air PollutantsMajor Air Pollutants Nitrogen oxides Nitrogen oxides andand nitric acid nitric acid: :

– Nitrogen oxide (NO) forms when nitrogen and Nitrogen oxide (NO) forms when nitrogen and oxygen gas in air react at the high-combustion oxygen gas in air react at the high-combustion temperatures in automobile engines and coal-temperatures in automobile engines and coal-burning plants. NO can also form from burning plants. NO can also form from lightening and certain soil bacteria.lightening and certain soil bacteria. NO reacts with air to form NONO reacts with air to form NO22..

NONO2 2 reacts with water vapor in the air to form nitric reacts with water vapor in the air to form nitric

acid (HNOacid (HNO33) and nitrate salts (NO) and nitrate salts (NO33--) which are ) which are

components of acid deposition.components of acid deposition.

Major Air PollutantsMajor Air Pollutants Sulfur dioxide (SOSulfur dioxide (SO22)) andand sulfuric acidsulfuric acid::

– About one-third of SOAbout one-third of SO22 in the troposphere occurs in the troposphere occurs

naturally through the sulfur cycle.naturally through the sulfur cycle.– Two-thirds come from human sources, mostly Two-thirds come from human sources, mostly

combustion (S+ Ocombustion (S+ O22 SO SO22) of sulfur-containing coal ) of sulfur-containing coal

and from oil refining and smelting of sulfide ores. and from oil refining and smelting of sulfide ores.

– SOSO2 2 in the atmosphere can be converted to sulfuric in the atmosphere can be converted to sulfuric

acid (Hacid (H22SOSO44) and sulfate salts (SO) and sulfate salts (SO442-2-) that return to ) that return to

earth as a component of acid deposition.earth as a component of acid deposition.

Major Air PollutantsMajor Air Pollutants Suspended particulate matter (SPM)Suspended particulate matter (SPM)::

– Consists of a variety of solid particles and liquid Consists of a variety of solid particles and liquid droplets small and light enough to remain droplets small and light enough to remain suspended in the air.suspended in the air.

– The most harmful forms of SPM are fine particles The most harmful forms of SPM are fine particles (PM-10, with an average diameter < 10 (PM-10, with an average diameter < 10 micrometers) and ultrafine particles (PM-2.5).micrometers) and ultrafine particles (PM-2.5).

– According to the EPA, SPM is responsible for According to the EPA, SPM is responsible for about 60,000 premature deaths a year in the U.S.about 60,000 premature deaths a year in the U.S.

Major Air PollutantsMajor Air Pollutants Ozone (OOzone (O33))::

– Is a highly reactive gas that is a major Is a highly reactive gas that is a major component of photochemical smog.component of photochemical smog.

– It can It can Cause and aggravate respiratory illness.Cause and aggravate respiratory illness. Can aggravate heart disease.Can aggravate heart disease. Damage plants, rubber in tires, fabrics, and paints. Damage plants, rubber in tires, fabrics, and paints.

Major Air PollutantsMajor Air Pollutants Volatile organic compounds (VOCs)Volatile organic compounds (VOCs)::

– Most are hydorcarbons emitted by the leaves of Most are hydorcarbons emitted by the leaves of many plants and methane.many plants and methane.

– About two thirds of global methane emissions About two thirds of global methane emissions comes from human sources.comes from human sources.

– Other VOCs include industrial solvents such as Other VOCs include industrial solvents such as trichlorethylene (TCE), benzene, and vinyl trichlorethylene (TCE), benzene, and vinyl chloride.chloride. Long-term exposure to benzene can cause cancer, Long-term exposure to benzene can cause cancer,

blood disorders, and immune system damage.blood disorders, and immune system damage.

Major Air PollutantsMajor Air Pollutants Radon (Rn)Radon (Rn)::

– Is a naturally occurring radioactive gas found in Is a naturally occurring radioactive gas found in some types of soil and rock.some types of soil and rock.

– It can seep into homes and buildings sitting It can seep into homes and buildings sitting above such deposits.above such deposits.

Case Study: Radioactive RadonCase Study: Radioactive Radon

Radon-222, a Radon-222, a radioactive gas radioactive gas found in some found in some soils and rocks, soils and rocks, can seep into can seep into some houses some houses and increase and increase the risk of lung the risk of lung cancer.cancer.

Sources and paths of entry Sources and paths of entry for indoor radon-222 gasfor indoor radon-222 gas.

Figure 19-13Figure 19-13