Unit 4 Air pollution - Tezpur University Unit 4 Study material.pdf · Unit 4 Air pollution ......
Transcript of Unit 4 Air pollution - Tezpur University Unit 4 Study material.pdf · Unit 4 Air pollution ......
9/16/2013
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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 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 Range Transport of Air Pollutants
Long-range transport of air
pollutants (LRTAP) refers to
the atmospheric transport of
air pollutants within a moving
air mass for a distance greater
than 100 kilometres.
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
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
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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:
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)
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;
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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.
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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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
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
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. ….
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HC- + O. Oxidized free radicals
NO NO2 + Aldehydes
O3
Balance of photochemical reaction shifts toward O3 build-up!!
Hydrocarbons shift photochemical reaction… 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
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
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How Acid Deposition Develops 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)
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
Alkenes (gasoline and aviation fuel) more reactive than alkanes - chains, oxides, halogenated HC CNS effects - cramps, tremor
GI tract - nausea, vomiting
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
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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
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 - 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
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!
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