CE 3231 - Introduction to Environmental Engineering and Science

CE 3231 - Introduction to Environmental Engineering and Science

Readings for This Class:

5.5-5.6

Ohio Northern University

Introduction Chemistry, Microbiology & Material Balance Water & Air Pollution Env Risk Management

Introduction to Air Quality

Every breath we take is affected by air quality. This lecture serves to introduce students to topics within air pollution and control technologies. Additional topics will be explored with more depth in subsequent lectures.

Lecture 26Introduction to Air Quality

(Air Quality I)

DO Sag Curve Modeling

Air Quality

Topics Covered Include: Introduction (Air Quality I) Atmospheric dispersion modeling (Air Quality II) Air pollution control technologies: Cyclones (Air Quality

III) Air pollution control technologies: Electrostatic

Precipitators (Air Quality IV)

Introduction: Air Pollution is all around us

• Indoor Air Pollution (home and work environment)• Local (near emission source)• Regional

– “Smog” and “Photochemical Smog”• Global

– Stratospheric Ozone Depletion– Global warming /climate change

Air Pollution Culprits

• Those that hurt you immediately– Smog (VOCs, O3, NOx, SOx)– Particulate Matter

• Those that hurt you long term– Ozone Depletion (The story of CFCs)– Green House Gasses

Introduction: London Smog incident of 1952

• Smog = smoke + fog• Adverse effects due to

soot particles + acid fog droplets

2 2 2 4( ) ( ) ( )SO g SO aq H SO aq http://www.metoffice.gov.uk/education/secondary/students/smog.html

Probably the most deadly air pollution event in human history– Lots of coal burning + stagnant

weather (foggy)– 4000 deaths with elevated death

rate lasted long after the event

Introduction: National Ambient Air Quality Standards (NAAQS)

(CO)

(Pb)

(NOx)

(SOx)

(O3)

APC: Smog (Effects)

• Ozone– Severe eye, nose and throat irritants– Lung damage– Plant damage, including leaf discoloration and cell collapse– A factor causing forest losses

• NO2

– Visibility reduction (brownish color)

Volatile Organic Carbon + NOx O3

APC: Smog

APC: SMOG (Formation of Ground Level Ozone)

• NO2 and O3 relationships• NO2 + uv NO + O

• O + O2 O3

• NO + O3 NO2 + O2

• Formation of OH radical• O3 + uv O2 + O

• O + H2O 2OH .

• VOC oxidation and NO2 relationship• VOC + OH . + O2 RO2

. + H2O

• RO2. + NO NO2 + RO.

APC: Sources of NOx

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APC: Average Emission of a Typical Car on the Road in 2002

FHWA-HEP-05-045

APC: Car vs. Truck Emissions

APC: Effects of PM

PM2.5 (<2.5 mm, respirable) and PM10 (<10 mm, thoracic)

APC: Effects of PM

• Health Effects– Asthma– Lung cancer– Cardiovascular issues– Premature death

• Visibility

Detailed damage mechanismunclear.

APC: PM Sources

Sources: dust, combustion

APC: Upper level ozone…a good thing

An orbit of retrieved GOME ozone profiles on October 22, 1997 overpass Indonesia in the tropics. The red line shows the NCEP tropopause.

O2+UV photon O + OO + O2 + M O3 + M

Both reactions are fast

Formation:

Destruction:O3+UV photon O2 +OO+O3 2O2

Second reaction is slow.O3 life time ~ 1-10 years.

APC: Ozone Depletion Mechanism…a bad thing

• CFCs (Chlorofluorocarbon) have shown to be the major cause of ozone depletion. – They are non-reactive in the troposphere due to lack of UV– They gradually fill the troposphere and diffuse into the

stratosphere

3 2

3 22Cl O ClO OClO O Cl O

3 3 23ClO O O

UVCFCs Cl

Net:

Step1: Photolysis (splitting by sunlight) of CFC’s in the stratosphere

Step2: Catalytic destruction of ozone

APC: However …

APC: Largest ozone hole – September 2006

• From September 21-30, 2006 the average area of the ozone hold was the largest ever observed. 11.4 million square miles

• (Area of USA: 3.5 million square miles)

http://www.nasa.gov/vision/earth/lookingatearth/ozone_record.html

APC: Green House gasses and recent surface temperature

variations

• Surface temperatures have shown significant fluctuation over the last 1000 years.

• Temperatures rose abruptly over the last century

• The cause of these changes is still debated although it can be captured reproducibly in the most sophisticated models.

APC: Green House Gasses (CO2 as a Green House Gas)

The Greenhouse Effect

APC: Green House Gasses (Global warming is only the beginning…)

• Sea level increase

APC: Green House Gases (Extreme Weather)

APC: The Kyoto Protocol

• UN treaty entered into enforce February 2005– Developed countries to reduce their green house emission

by an average of 5% below their 1990 level. • EU: 8%• US: 7%• Japan: 6%

– United States signed the protocol but did not ratify the treaty

APC: Participation in the Kyoto Protocol

Participation in the Kyoto Protocol: dark green indicates countries that have signed and ratified the treaty, yellow indicates those that have signed and hope to ratify it, and red indicates those that have signed but not ratified it.