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ES 541

Contemporary Environmental

Issues

Unit 4

Air pollution

Atmosphere as a Resource

Atmospheric Composition Nitrogen 78.08%

Oxygen 20.95%

Argon 0.93%

Carbon dioxide 0.04%

Ecosystem services Blocks UV radiation

Moderates the climate

Redistributes water in the hydrologic cycle

Life-Air

Air? Not Ordinary Air!

It is Life-Air from the Skies!

• Without ‘Food’ (but ‘Water’) human can live for ‘3

Days’.

• Without ‘Water’ (and no ‘Food’) human can live

for ‘1 Day’.

• Without ‘Air’ (even with ‘Food’ and ‘Water’)

human can live for ‘1 Minute’.

Ques: Guess, what is ‘Death’?

Ans: No Air for ‘1 Minute’ is called as ‘Death’.

Air is so

important.

Pollution is

a serious

issue.

Air is Expensive than Blood

Air is what we Breathe every Second, even during Sleep!

• Air is sucked into lungs every few seconds and the alveolar

system of the lungs helps the oxygenation of blood in every

drop.

• Heart pumps Blood and Blood carries O2 (by Hemoglobin) to

every part/cell of the body to sustain Life inside.

• ‘More O2’ into the body is called ‘More Life’.

• Similarly ‘Better O2’ into the body is called ‘Better Life’.

• But then ‘Polluted O2’ into the body is called ‘Polluted Life’.

THE RESULT OF EMISSION INTO THE AIR OF HAZARDOUS SUBSTANCES AT

A RATE THAT EXCEEDS THE CAPACITY OF NATURAL PROCESSES IN THE ATMOSPHERE TO CONVERT,

DEPOSIT, OR DILUTE THEM…

What is air pollution Factors that affect air pollution

Emissions (traffic, industrial, domestic)

Geography (terrain)

Weather conditions (rain, winds, humidity)

Season

Time of day

Population density

Indoor vs outdoor

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Types of air pollution

Aerosols Particulates solid phase

Dust

Ash

Fumes

Solid and liquid Smoke (from combustion)

Coastal aerosols

Liquid

Aggregate gases (sulfate, nitrate)

Gases COx

SOx

NOx

PAH

Types and Sources of Air Pollution

Two categories

Primary Air Pollutant

Harmful 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

Six primary or “criteria” air pollutants

Carbon monoxide (CO)

Ozone (O3)

Nitrogen dioxide (NO2)

Sulfur oxides (SOx)

PM2.5 and PM10

Lead (Pb)

Major Air Pollutants Types of air pollution

Individual pollutants

Reducing pollution (SO2) Acid rain (fog)

Corrosive, eroding

Photochemical pollution Aldehydes, electrophilic HCs

Oxidative, carcinogenic?

Mixtures and complex patterns

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Combustion pollutants

VOCs

NOx

N-organics

Halo-organics

Metals

CO

Sources of combustion

Tobacco

Power plants

Incinerators

Automobiles

Industry

Diesel pollutants

Particulate matter C + PAHs + N-aromatics

Gases NOx, CO, SOx

VOCs formaldehyde, acrolein, aldehydes

Respiratory inflammation

Cytotoxicity to airway cells

Outdoor air pollution

Beijing

Delhi

Outdoor air pollution

Mexico City

Santiago

Air Pollution - Side Effects

Acid Rain - and therefore Water Pollution.

Global Warming 1 - due to Air Pollution.

Ozone Layer Depletion - due to Air Pollution.

Global Warming 2 - due to Ozone Layer Depletion.

Increase of Smog, Haze, Particulate, Dust, Toxic Brue.

Global Dimming - due to Air Pollution.

Ecological Issues - too much Rain or no Rain - destruction of Farmers plans - Farmer suicides in some Countries - Ethiopian famine, etc.

Environmental Disorder - disturbs natural Human Life.

Side Effects of Air Pollution are many!

A few are mentioned below:

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Air Pollution - 2 Sides of the Coin

1. Pollution / 2. Deforestation

• Pollution: Pollution is the main cause for Global Warming.

• Deforestation: Forests/Vegetation on the side have the capacity

to take the carbon oxides and purify the air around by releasing

oxygen, thus nullifying pollution to some extent.

• But in the present day scenario, pollution is increasing every

second, and same time on the other side deforestation is

happening at rapid speed and is supporting the acceleration of

Air Pollution as a catalyst.

Present Need of the Hour

1. Arise 2. Awake

3. Attend 4. Act

Other Pollutions/Corruptions

Water Pollution.ppt

Food Pollution.ppt

Sound Pollution.ppt

Society Pollution.ppt

Politics Pollution.ppt

Reservations Pollution.ppt

Government Pollution.ppt

Law & Order Pollution.ppt

• Strikes/Riots Pollution.ppt

• Relationships Pollution.ppt

• Cultures Pollution.ppt

• Religions Pollution.ppt

• Mind Pollution.ppt

• Quality of Thought Pollution.ppt

• Security Pollution.ppt

• Health Pollution.ppt

Indoor pollutants

Non-specific symptoms

Household vs work space

Sick building syndrome (20% exposed) Cigarette smoke, combustion products

Organic offgasing (glue, fabrics, furnishings)

Biological agents (infections, allergens)

Additional factors (stress, fatigue, diet, alcohol)

Indoor air quality

Indoor air quality (IAQ) is a term referring to the air quality within and around buildings and structures.

IAQ can be affected by microbial contaminants (mold, bacteria), gases (including carbon monoxide, radon, volatile organic compounds), and particulates.

Indoor air pollution: Poor countries

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Control of Indoor Air Pollution

Basic approaches to control indoor air pollution include source control, source isolation, increased ventilation, dehumidification, and the use of filters. Possible sources of contamination are eliminated in a source-control strategy. Examples include banning smoking in public buildings.

Source-isolation strategy is used in situations where a

source cannot be completely eliminated. For instance,

copy machine areas, food service stations, and

bathrooms are often separately vented outside buildings

to avoid the recirculation of return air.

What is sick building syndrome ?

The feeling of illness among majority of

occupants of a conditioned space is called “Sick Building Syndrome”.

A variety of illness symptoms reported by

occupants in sick buildings are – Headache, fatigue, irritation in eyes, nose and throat, shortness of breathe etc.

Causes :Inadequate ventilation, insufficient supply

of outside air; poor mixing; fluctuations in

temperature & humidity;

Main indoor pollutants and their sources

Main indoor air pollutant and their sources,continue

Sources Pollutant

Cigarette and water pipe smoking Environmental

tobacco smoke

Unburned kerosene, gas water

heaters, gas stoves, automobile

exhaust, tobacco smoke

Carbon monoxide

Lead based paints, contaminated

soil, dust and drinking water

Lead

Deteriorating, damaged, or

disturbed insulation, fireproofing,

acoustical materials, and floor tiles

Asbestos

Kerosene heaters, un-vented gas stoves and heaters.

Environmental tobacco smoke

NO2

Furniture made with pressed wood products, urea-

formaldehyde foam insulation, environmental

tobacco smoke, glues

Formaldehyde

Paint, paint stripper, solvent aerosol sprays Volatile organic compounds

Kerosene heaters, wood stoves, fireplaces,

environmental tobacco smoke

Respirable particles

Dust mite, Pet dander, droppings and body parts of

cockroaches rodents and other pests

Biological pollutants

Building materials and well water Radon

Main indoor air pollutant and their sources

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2200

Particulate matter pollution

Properties - varied Mixture of solid phase and absorbed materials (organic,

inorganic and biological) Carbonaceous core 40-60%, C 7%

Sources Combustion - oil and coal

Industry Automobiles

Tobacco smoke Biomass burning Metal smelters

NAAQS:

PM10: 150ug/m3, 24h

50ug/m3, annual

PM2.5 15ug/m3, annual

65ug/m3, 24h

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Particulates - features

Physical size

Large

Small ~10um

Fine ~2.5um

Aerodynamic diameter (size equivalent of density=1)

Large - local irritation (>100um)

Inhalable (<100um)

Thoracic fraction (<20um)

Coarse PM10 (<10um)

Fine PM2.5 (<2.5um)

Ultrafine (<0.1um)

Chemical reactivity

Shape (fibers) and Water content

respirable

Urban Particulates

• In the <2.5um range

• Large water content, trace metals,

acid gases, organic chemicals,

biological

• Rather uniform distribution

• Include diesel

Health effects of particulate pollutants

Eye irritation

Respiratory tract infection

Exacerbation of asthma

Bronchial irritation

Heart disease

Possibly cancer (controversial) (diesel, TiO2, talc, carbon black, toner black)

Elevated hospital admissions, mortality

Causation(s) not fully understood

- starting at 10ug/m3

Gaseous pollutant features

Chemical reactivity (ozone)

Solubility in water Soluble

Ambient (NOx, SOx)

Occupational (Hydrochloric acid, Ammonia)

Less soluble

H2S, ozone

Gas pollutants - SO2

Properties Reacts with H2O and forms sulfurous acid (H2SO3), which

oxidizes to sulfuric acid (H2SO4) Chemical transformation of other pollutants Responsible for acid rain effect

Sources Biomass and fossil fuel combustion Industrial emissions, smelters

Controls Low-S fossil fuels (clean coal) Emission control devices

London fog episode (acute) NAAQS: 0.03ppm, annual

0.14ppm, 24h

SO2 …continued

Absorption at upper respiratory tract (sulfite, bisulfite)

Health effects (starting at <1ppm) Respiratory tract irritation, bronchoconstriction Pulmonary function impairment Increased air flow resistance Bronchitis Exacerbation of heart diseases

Short acute: 2min 0.4-1ppm in asthmatics Long term, low levels

Impairs immune pulmonary defenses Susceptibility to infections

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Gas pollutants - H2SO4

Product of SO2 With metals and water --> sulf. Fly ash and acid rain

Protonates biomolecules - membrane damage

Bronchoconstriction

Increased air flow resistance

Mucus secretion protects (buffer) - nose inhalation

Asthmatics are more sensitive

Acidity interferes with mucociliary clearance Chronic exposure to 100g/m3 : lower respiratory damage,

macrophage mediated

Gas pollutants -NO2

Properties Oxidant, less potent than O3

Sources NO oxidation

High To combustion (automobiles, power plants) Indoor - kerosene, gas stoves, ETS

Silos in farming (75-100ppm)

Health effects - starting at 1.5-2ppm

Deep lung irritant - terminal bronchioles

Alveolar cells, ciliated epithelia, Clara cells

Similar to ozone but less inflammatory (if < 2-5ppm)

Enhanced infection, suppression of macrophage action Peaks more

NAAQS: 0.05ppm, annual

Gas pollutants - CO

Properties Odorless, heavier than air, stronger binder to Hb than O2

Sources Incomplete combustion Traffic (inside the car, parking garages, tunnels is highest) Inside cars = 3x urban streets, and = 5x residential streets

Health effects Asphyxiant Fatigue, confusion, headaches, dizziness, cardiac function (arrhythmias,

angina) Start at 2.5% COHb (0.5% baseline) (air level 50ppm for 90min) 2ppm COHb, no effect >5ppm COHb, cardiovascular effects 40ppm COHb, is fatal

NAAQS: 9ppm, 8h

35ppm, 1h

Gas pollutants - O3

Good O3 - stratosphere

Bad O3 - troposphere

Properties Short lived, highly reactive, water soluble

Scrubbed in nasopharynx

Reaches terminal bronchioles and alveoli

Sources Photochemical reactions

Health effects Degenerative lung disease

Loss of lung function

NAAQS: 0.12ppm, 1h

0.08ppm, 8h

Photochemical pollution

NO2 NO + O O2 + O O3

O3 + NO O2 + NO2

uv

Twist:

In absence of HC- the reaction reaches equilibrium

Car emitted HC- (PAH) react with O. ….

HC- + O. Oxidized free radicals

NO NO2 + Aldehydes

O3

Balance of photochemical reaction shifts toward O3 build-up!!

Hydrocarbons shift photochemical reaction…

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Photochemical pollution

uv

O3 NO2

Hydrocarbons O2

O2.

O3

O .

H2O

2 (HO.)

The O3 molecule is highly reactive

• Ultimate toxicant: • No enzyme can detoxify it • Only protection: prevention of its formation

What’s in smog

particulates (especially lead)

nitrous oxides

potassium

Carbon monoxide

Other toxic chemicals

Acid rain

contains high levels of sulfuric or nitric acids

contaminate drinking water and vegetation

damage aquatic life

erode buildings

Alters the chemical equilibrium of some soils

Other air pollutants - HAPs

Hazardous air pollutants Not included in the 6 criteria air pollutants

Include Organic chemicals (acrolein, benzene)

Minerals (asbestos)

PAH (benzo[a]pyrene)

Metals (Hg, Be)

Pesticides (carbaryl, parathion)

Some are carcinogenic

Volatile Organic Pollutants (VOCs)

Sources: Petroleum emissions, fuel combustion, incineration, biomass burning

Account for ~14% of all air pollution Important factor of indoor air pollution Types

Aliphatic Alcohols (ethylene glycol, MTBE) Aldehydes (formaldehyde) Aromatic (benzene, toluene, xylene) Halogenated (TCE, PERC, Methylene Chloride) Polycyclic (PAHs) Other (Carbon disulfide)

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VOCs Health Effects

Alkanes (solvents, varnishes, lacquers)

Irritants, lung and skin

CNS depressants, neuron degeneration, paralysis

Pulmonary edema

React with OH radical in photochemical pollution

VOCs Health Effects

Alkenes (gasoline and aviation fuel) more reactive than alkanes - chains, oxides, halogenated HC

CNS effects - cramps, tremor

GI tract - nausea, vomiting

NAAQS - CAA 1990

National Ambient Air Quality Standards ug/m3 or ppm

National Air Quality and Emissions Trends Report

NAAQ Standards for six “criteria” pollutants

http://www.epa.gov/air/criteria.html

Pollutant Primary Stds. Averaging Times Secondary Stds.

9 ppm

(10 mg/m3)

35 ppm

(40 mg/m3)

Lead 1.5 µg/m3 Quarterly Average Same as Primary

0.053 ppm

(100 µg/m3)

Revoked(2) Annual(2) (Arith. Mean)

150 µg/m3 24-hour(3)

15.0 µg/m3 Annual(4) (Arith. Mean)

35 µg/m3 24-hour(5)

Ozone 0.08 ppm 8-hour(6) Same as Primary

0.12 ppm * 1-hour(7) Same as Primary

0.03 ppm Annual (Arith. Mean) -------

0.14 ppm 24-hour(1) -------

------- 3-hour(1) 0.5 ppm

(1300 µg/m3)

Particulate Matter

(PM10)

Sulfur Oxides

Particulate Matter

(PM2.5)

None

None

Same as Primary

Same as Primary

Nitrogen Dioxide

Carbon Monoxide

1-hour(1)

8-hour(1)

Annual (Arithmetic Mean)

*Applies only in limited areas

US Regulation history

1947 CA - Air pollution control Act 1955 - Truman’s Air pollution control Act 1963 Federal - Clean Air Act (1967 am) 1965 Federal - Motor vehicle Air pollution control Act 1970 The Clean Air Act: national level (EPA)

O3, SO2, NO2, CO, PM, Pb, total hydrocarbons (dropped)

1970 Lead is banned as fuel additive 1990 CCA amendment: 118 chemicals, some carcinogenic

Maximum achievable control technology Additional risk assessment if health effects beyond the MACT level Emission standards for motor vehicles (CO solution - MTBE new

problem)

1997 New standard for PM2.5

Clean Air Mercury and Interstate rules

On March 15, 2005, EPA issued the Clean Air Mercury Rule to permanently cap and reduce mercury emissions from coal-fired power plants for the first time ever. This rule makes the United States the first country in the world to regulate mercury emissions from utilities.

On March 10, 2005, in a separate but related action, EPA issued the Clean Air Interstate Rule (CAIR), a rule that will dramatically reduce air pollution that moves across state boundaries.

Together the Clean Air Mercury Rule and the Clean Air Interstate Rule create a multi-pollutant strategy to reduce emissions throughout the United States.

http://www.epa.gov/air/mercuryrule/

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Controlling Air Pollution

Smokestacks with electrostatic precipitator (right)

Without

Electrostatic

precipitator

With

Electrostatic

precipitator

Controlling Air Pollution

Smokestacks with scrubbers (right)

Particulate material can also be controlled by proper excavating techniques

Controlling Air Pollution

Phase I Vapor Recovery System for gasoline

Catalytic Converters and Particle Traps

Catalytic converters can be fitted to cars to reduce NOx emissions.

CO + HC + NOx H2O + N2 + CO2

Platinum Honeycomb

Particle traps can be used to reduce PM10 and NOx, but the effectiveness is severely reduced if the fuel the vehicle burns has a high sulphur content.

The major target in the battle for cleaner cities is diesel.

Multi-pollutant/multi-effect analysis

for identifying cost-effective policy scenarios

SO2 NOx VOC NH3 PM

Health Acidification Eutrophication Ozone

RAINS

computer model

CAFE policy targets

for 2020

The Clean Air Act

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!

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Other Ways to Improve Air Quality

Reduce sulfur content in gasoline from its current average of 330 ppm to 30 ppm Sulfur clogs catalytic converters

Require federal emission standards for all passenger vehicles Including SUVs, trucks and minivans

Require emission testing for all vehicles

Including diesel

Ozone Depletion in Stratosphere

Ozone Protects earth from UV radiation Part of the electromagnetic spectrum with wavelengths just

shorter than visible light

Ozone Depletion in Stratosphere

Ozone thinning/hole First identified in 1985 over

Antarctica

Caused by human-produced bromine and

chlorine containing chemicals

Ex: CFCs

Ozone Depletion in Stratosphere

Hole over Antarctica requires two conditions: Sunlight just returning to polar region

Circumpolar vortex- a mass of cold air that circulates around the southern polar region

Isolates it from the warmer air in the rest of the planet

Polar stratospheric clouds form Enables Cl and Br to destroy ozone

Effects of Ozone Depletion

Higher levels of UV-radiation hitting the earth

Eye cataracts

Skin cancer (right)

Weakened immunity

May disrupt ecosystems

May damage crops and forests

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Recovery of Ozone Layer

Montreal Protocol (1987) Reduction of CFCs

Started using HCFCs (greenhouse gas)

Phase out of all ozone destroying chemicals is underway globally

Satellite pictures in 2000 indicated that ozone layer was recovering

Full recovery will not occur until 2050

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

How Acid Deposition Develops Effects of Acid Deposition

Declining Aquatic Animal Populations

Thin-shelled eggs prevent bird reproduction Because calcium is unavailable

in acidic soil

Forest decline Ex: Black forest in Germany

(50% is destroyed)

Acid Deposition and Forest Decline 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 gasoline

5 worst cities in world

Beijing, China; Mexico City, Mexico; Shanghai, China; Tehran, Iran; and Calcutta, India

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Long Distance Transport of Air Pollutants