Principles of Environmental Engineering and Sustainability - PowerPoint Presentation

Slide1

Principles of Environmental Engineering and Sustainability

Lecture

Five: Air

Pollution

Department of Environmental Engineering

Slide2

OUTLINE

Atmosphere as a Resource

Types and Sources of Air Pollution

Major Classes of Air Pollutants

Urban

Air Pollution

Controlling

Air

Pollution

Acid Deposition and acid precipitation

Air pollution concentration expressions

Slide3

Atmosphere as a Resource

Atmospheric Composition

Nitrogen 78.08%

Oxygen 20.95%

Argon 0.93%

Carbon dioxide 0.04%Ecosystem servicesBlocks UV radiationModerates the climateRedistributes water in the hydrologic cycle

Slide4

Types and Sources of Air Pollution

Air Pollution

Chemicals added to the atmosphere by

natural

events or

human activities in high enough concentrations to be harmful Two categoriesPrimary Air PollutantHarmful substance that is emitted directly into the atmosphere

Secondary Air Pollutant

Harmful substance formed in the atmosphere when a primary air pollutant reacts with substances normally found in the atmosphere or with other air pollutants

Slide5

Peroxyacetyl nitrate

(PAN) is a component of photochemical smog, which is a mixture of air pollutants that includes both gases and particulates, some of which react with sunlight.

HNO

2

:Nitrous Acid

HNO3:Nitric Acid

Major Classes of Air Pollutants

:

Particulate Material

Nitrogen Oxides

Sulfur Oxides

Carbon Oxides

Hydrocarbons

Ozone

Slide6

Major Air Pollutants

Slide7

Major Air Pollutants

Particulate Materials

Thousands

of different solid or liquid particles suspended in air

Includes:

soil particles, soot, lead, asbestos, sea salt, and sulfuric acid droplets Nitrogen Oxides

Gases produced by the chemical interactions between atmospheric nitrogen and oxygen at high

temperature, greenhouse gases

Sulfur Oxides

Gases produced by the chemical interactions between sulfur and oxygen

Causes acid precipitation

Carbon Oxides

Gases carbon monoxide (CO) and carbon dioxide (CO

2

)

Greenhouse gases

Hydrocarbons

Diverse group of organic compounds that contain only hydrogen and carbon (ex: CH

4

-

methane

), greenhouse gas

Slide8

Ozone

Tropospheric Ozone

Man- made pollutant in the lower atmosphere

Secondary air pollutant

Component of photochemical

smogGreenhouse gasStratospheric Ozone

Essential component that screens out UV radiation in the upper atmosphere

Man- made pollutants (ex: CFCs) can destroy it

Slide9

Ozone Depletion in Stratosphere

Ozone thinning/hole

First identified in 1985 over Antarctica

Caused by

human-produced bromine and chlorine containing chemicals

Example: CFCs

Slide10

Sources of Outdoor Air Pollution

Two main sources

Transportation

Industry

Intentional forest fires is also high

Slide11

Urban Air Pollution

Photochemical Smog (ex: Los Angeles below)

Brownish-orange haze formed by chemical reactions involving sunlight, nitrogen oxide, and hydrocarbons

Slide12

Formation of Photochemical Smog

Slide13

Effects of Air Pollution

Low level exposure

Irritates eyes

Causes inflammation of respiratory tract

Can develop into chronic respiratory diseases

Slide14

Health Effects of Air Pollution

Sulfur Dioxide and Particulate material

Irritate respiratory tract and impair ability of lungs to exchange gases

Nitrogen Dioxides

Causes airway restriction

Carbon monoxide

Binds with iron in blood hemoglobin

Causes headache, fatigue, drowsiness, death

Ozone

Causes burning eyes, coughing, and chest discomfort

Slide15

Children and Air Pollution

Greater health threat to children than adults

Air pollution can restrict lung development

Children breath more often than adults

Children who live in high ozone areas are more likely to develop asthma

Slide16

Air Quality

Air Quality Index

Protect Your Health

Good

0-50

No health impacts are expected when air quality is in this range.

Moderate

51-100

Unusually sensitive people should consider limiting prolonged outdoor exertion.

Unhealthy for Sensitive Groups

101-150

Active children and adults, and people with respiratory disease, such as asthma, should limit prolonged outdoor exertion.

Unhealthy

151-200

Active children and adults, and people with respiratory disease, such as asthma, should limit prolonged outdoor exertion, everyone else, especially children should limit prolonged outdoor

excertion

.

Very Unhealthy (Alert)

201-300

Active children and adults, and people with respiratory disease, such as asthma, should limit prolonged outdoor exertion everyone else, especially children, should limit outdoor exertion.

Slide17

Controlling Air

Pollution

Smokestacks with electrostatic precipitator (right)

Without Electrostatic precipitator

With Electrostatic precipitator

Slide18

Smokestacks with scrubbers (right)

Controlling Air

Pollution

A suspension of fine drops of a liquid in a gas

Slide19

The Clean Air

Act (USA)

Authorizes EPA to set limits on amount of specific air pollutants permitted

Focuses on 6 pollutants:

lead, particulate matter, sulfur dioxide, carbon monoxide, nitrogen oxides, and ozone

Act has led to decreases!

Slide20

Acid Deposition

Sulfur dioxide and nitrogen dioxide emissions react with water vapor in the atmosphere and form acids that return to the surface as either dry or wet deposition

pH scale

Slide21

How Acid P

recipitation

Develops

Slide22

Air Pollution Around the World

Air quality is deteriorating rapidly in developing countries

Shenyang, China

Residents only see sunlight a few weeks each year

Developing countries have older cars

Still use leaded gasoline5 worst cities in worldBeijing, China; Mexico City, Mexico; Shanghai, China; Tehran, Iran; and Calcutta, India

Slide23

Non-industrial, non-regulated sources of in-door air pollution

Source: AirAdvice, Inc.

Slide24

Air Pollution Concentration (Two main ways this is expressed)

Mass Per Unit

Volume:

Mass

of air pollutant per cubic meter of air

Used for solid, liquid and gaseous air pollutantsGrams per cubic meter (g/m3)Milligrams per cubic meter (

mg/

m

3

)

= 0.001

g/

m

3

Micrograms

per cubic meter (

μg/

m

3

)

= 0.001

mg/

m

3

=

1.0 ×

10

-6

g/

m

3

Parts

Per Million (ppm

):

#

of molecules of air pollutant per million molecules of ai

r

Used for gaseous air pollutants

1 part per billion (ppb) = 0.001 ppm

1 part per trillion (

ppt

) = 0.001 ppb = 1.0 ×10

-6

ppm

Slide25

Class Exercise: Part

1

Express the following situations in terms of the air pollution concentration (use metric units)

:

500

milligrams of carbon monoxide in a 10 ft

x 10

ft

x 10

ft

room

10 milligrams of ozone in a 1000 cubic-meter warehouse

Note: 10 feet = 3.048 meters

Slide26

Class Exercise: Part

1

…cont.

Express the following situations in terms of the air pollution concentration (use metric units):

500 mg of carbon monoxide in a 10

ft x 10 ft

x 10

ft

room = 500 mg/28.3 m

3

= 17.7 mg/

m

3

10 milligrams of ozone in a 1000 cubic-meter warehouse = 10 mg/1000

m

3

= 0.01 mg/

m

3

= 10

μg

/

m

3

Slide27

Class Exercise: Part

2

Are the concentration levels of Part 1 of concern in terms of air pollution?

For the threshold value, use the lowest (i.e. most strict) 1-hour concentration standard for carbon monoxide and ozone for California

.

Slide28

Class Exercise: Part 2

…cont.

We looked at following situations:

500 mg of carbon monoxide in a 10

ft

x 10

ft

x 10

ft

room

= 17.7 mg/m

3

. California 1-hour standard for carbon monoxide is 23 mg/

m

3

. Values are fairly close. Therefore, yes, carbon monoxide at this concentration level is of concern in terms of air pollution.

10 milligrams of ozone in a 1000 cubic-meter warehouse

= 10

μg

/

m

3

. California 1-hour standard for ozone is 183

μg

/

m

3

& 8-hour standard is 137

μg

/m3. Value is much less. Therefore, no, ozone at this concentration level is not of concern in terms of air pollution.

Slide29

End of Lecture Five