AIR and AIR POLLUTION
Learning Objectives
Review: Identify the layers of the
atmosphere.
• Greek: atmos
(vapor/steam),
sphaira (ball/ globe)
• Modern Latin:
atmosphaera
• Gaseous envelope
surrounding the
Earth
3
§ The total mass of the
atmosphere is about 5.3 x
1018 kg
§ Water is excluded from
this table because its
concentration in air can
vary drastically from
location to location.
Troposphere
Stratosphere
Mesosphere
Thermosphere (Ionosphere)
Exosphere
§ Closest to Earth’s surface (7-18 km above the
equator)
§ Most active region – where all the dramatic events
of weather (rain, lightning, hurricanes) occur
§ Contains almost 80% of the total mass of air and
practically all the atmosphere’s water vapor (forms
clouds and rain)
§ Thinnest layer of the atmosphere (10 km)
§ Temperature decreases with increasing altitude
§ Consists of nitrogen, oxygen and ozone.
§ 19-50 km above the equator
§ Air temperature increases with altitude due to
the exothermic reactions triggered by UV
radiation from the sun.
§ One of the products of this reaction sequence
is ozone (O3), which serves to prevent harmful
UV rays from reaching Earth’s surface.
§ 30-50 km above the equator
§ The concentration of ozone and
other gases is low
§ The temperature decreases again
with increasing altitude
§ 50-400 km above the equator
§ Temperature increases with altitude – as the
result of the bombardment of molecular O2
and N2 and atomic species by energetic
particles, such as electrons and protons, from
the sun.
§ In reverse, these processes liberate the equivalent
amount of energy, mostly heat.
§ Ionized particles are responsible for the reflection of
radio waves back toward Earth.
§ ~400 km above the equator
§ The outermost layer of our atmosphere
§ This layer separates the rest of the
atmosphere from outer space – 10,000
km thick
§ There is a lot of empty space in
between of very spread out hydrogen
and helium gases.
§ There is no air to breathe and it is very
cold.
§
§
Spectacular celestial light shows as a result of
ejection of myriad electrons and protons in space
during solar flares or violent eruptions on the
surface of the sun.
§
Aurora borealis – Northern Hemisphere;
§
Aurora australis – Southern Hemisphere
These electrons and protons collide with the
molecules and atoms in Earth’s upper
atmosphere, causing them to ionized and
electronically excited.
e- + O
O* + e-
p+ + N2
N2+* + p+ + e-
Solar Radiation
§
The excited molecules and ions return to the ground state with the
emission of light.
§
An excited oxygen atom emits photons at wavelengths of 558 nm
(green) and between 630 and 636 nm (red).
§
The blue and violet colors often
observed in auroras result from the
transition in the ionized nitrogen
molecule. The wavelengths for this
transition fall between 391 and 470 nm.
• The atmosphere performs
several ecosystem services:
• Protects Earth from most
radiation from the sun
and space
• X-rays, Cosmic rays
and Ultraviolet (UV)
• Without this
atmospheric radiation
shield, life as we know
it would cease to exist
§
Ozone (O3) in the stratosphere prevents
UV radiation emitted by the Sun from
reaching the Earth’s surface.
§
photodissociation of molecular oxygen :
𝑂!
§
UV <240 nm
𝑂+𝑂
reactive O atom combines with molecular oxygen (O2) to
form ozone (O3)
𝑂 + 𝑂! + 𝑀 → 𝑂" + 𝑀
§
Formed ozone absorbs UV light
𝑂"
UV
𝑂 + 𝑂!
where: M = inert substance (N2)
• The atmosphere performs
several ecosystem services:
– Naturally occurring greenhouse
gases absorb some reradiated
heat
• Keeps surface temperature within
habitable range for life to exist
§
The trapping of heat near Earth’s
surface by gases in the
atmosphere, particularly CO2.
– Atmosphere is modified and partially maintained by living
organisms
• Photosynthesis contributes O2 , cellular respiration CO2
Learning Objectives
Identify the types, sources, and
effects of chemicals that pollute
the air.
WHAT IS AIR
POLLUTION?
The presence of various chemicals in the atmosphere in
concentrations high enough to harm organisms, ecosystems,
or human-made materials, or to alter climate
• Primary Air Pollutant
Øchemicals or substances
emitted directly into the air
from a source (natural
processes and human
activities) at concentrations
high enough to cause harm
• Secondary Air Pollutant
ØHarmful substance formed in
the atmosphere when a
primary air pollutant reacts
with substances normally
found in the atmosphere or
with other air pollutants
Natural Sources:
• wind-blown dust
• Pollutants from wildfires and
volcanic eruptions
• Volatile organic chemicals
released by some plants
Ø Spread out over the globe
Ø Removed by chemical cycles,
precipitation, and gravity
Ø Some chemicals emitted by
volcanic eruptions or forest
fires can temporarily reach
harmful levels
Human (Anthropogenic) Sources:
• combustion of fossil fuels
• industrial by-products
Types of Human Sources:
• Mobile sources - such as cars, buses, planes, trucks, and
trains
• Stationary sources - such as power plants, oil refineries,
industrial facilities, and factories
OUTDOOR
POLLUTION
This refers to
exposures that
occurs outside of the
built environment.
Ozone (O3)
§ Has a sharp odor that you may have detected
around electric motors or welding equipment
§ Can be found both in troposphere and
stratosphere
§ At troposphere, it is as major part of smog
§ At stratosphere, it is a protective layer against
UV radiation (ozone layer)
§ Formed when nitrogen oxides (NOx) and volatile
organic compounds (VOCs) combine chemically
with oxygen in sunlight
Carbon Monoxide (CO)
§ “the silent killer” – no color, taste, nor smell
§ CO is released when engines burn fossil fuels – automobile exhaust,
charcoal fires, propane pumping stoves
§ When inhaled, CO passes into the
bloodstream and interferes with
the ability of the hemoglobin to
carry oxygen
•
Carbon dioxide (CO2)
– Colorless, odorless, tasteless gas
– Greenhouse gas
– Major sources: 93% of CO2 in the atmosphere is
the result of the natural carbon cycle; human
activities – burning of fossil fuels, clearing of CO2–
absorbing forests and grasslands
Nitrogen Oxides (NOx)
§ Refer to a binary compound of nitrogen and
oxygen, or a mixture of such compounds
§ NO: nitric oxide
§ NO2: nitrogen dioxide
§ N2O: nitrous oxide
§ N4O: nitrosylazide
§ Formed when N in the fuel is burned or when N in
the air reacts with O at very high temperature
– vehicle engines and coal-fired power plants
Nitrogen Monoxide (NO)
§ Common name: nitric oxide
§ A colorless gas
Nitrogen Dioxide (NO2)
§ NO2 is a reddish-brown gas that comes from the
burning of fossil fuels
§ Has a strong smell at high levels
§ Primary visible component of urban smog
§ Can also react in the atmosphere to form ozone, acid rain or
particles
§ Can combine with the moist tissue in lungs to produce an acid
Dinitrogen Monoxide (N2O)
§ Common name: nitrous oxide
§ Greenhouse gas emitted from fertilizers and animal
wastes, and is produced by the burning of fossil fuels
§ It is the largest cause of ozone layer depletion.
Sulfur Oxides (SOx)
• Refer to a binary compound of sulfur and
oxygen, or a mixture of such compounds
§ SO: sulfur monoxide
§ SO2: sulfur dioxide
§ SO3: sulfur trioxide
§ S2O: disulfur monoxide
§ S2O2: disulfur dioxide
§ Lower sulfur oxides (S7O2, S6O2)
§ Higher sulfur oxides (SO3, SO4, etc.)
Sulfur Dioxide (SO2)
§ SO2 is a corrosive gas that cannot be seen or smelled at low levels
but can have a “rotten egg” smell at high levels
§ Mostly comes from burning of coal or petroleum in power plants;
also comes from factories that make chemicals, paper or fuel
§ Like NO2, it reacts in the atmosphere to form acid rain
§ SO2 exposure can affect people with asthma or emphysema by
making it more difficult to breathe
§ Also irritates eyes, noses and throats
§ Can harm trees and crops, as well as damage buildings
Sulfur Trioxide (SO3)
§ a secondary air pollutant that forms when SO2 reacts with oxygen in
the air
§ reacts with water to form sulfuric acid
Particulate Matter (PM)
§ Solid or liquid matter that is suspended in the air
§ To remain in the air, particles must be less than 0.1 mm wide
and can be as small as 0.00005 mm
§ Divided into 2 types: coarse particles and fine particles
§ Coarse particles: road dust, sea spray, construction
§ Fine particles: burning of fuels in power plants and
automobiles
§ Can enter the lungs - asthma attacks, respiratory problems,
premature death
§ Reduces visibility and corrodes metals
Particulate Matter (PM): PM2.5 and PM10
§ PM10
§ particles with an average
diameter of 10 μm (1.0 x
104 nm), length on the
order of 4 x 10-4 (0.0004)
inches or one-fifth of the
width of a human air.
§ PM2.5
§ is a subset of PM10 and includes particles with an
average diameter 2.5 um (2.5 x 103 um) or less.
https://blissair.com/what-is-pm-2-5.htm
Particulate Matter (PM)
https://www.ucair.org/pollutants/pm2-5/
Sources: 62% natural sources – dust,
wild fires, sea salt; 38% human sources –
coal-burning power and industrial plants,
motor vehicles, road constructions
http://www.bestratedairpurifier.in/pm2-5-pm10-effects-human-health/
Lead
§ Blue-gray metal that is very toxic and
found in a number of forms and locations
§ From cars in areas where leaded gasoline
is used; from power plants and other
industrial sources
§ Lead paint (peeling paint), lead in old
pipes (drinking water)
§ High amounts can be dangerous for small
children that may cause lower IQ and
kidney problems
§ In adults, increased chances of heart
attack and/or stroke
Toxic Air Pollutants (TAPs) or Hazardous air pollutants
(HAPs)
§ Each toxic air pollutant comes from a slightly different source, but
many are created in chemical plants or are emitted when fossil
fuels are burned
§ Chlorine, formaldehyde, arsenic, asbestos, benzene and dioxin
§ Asbestos and formaldehyde can be found in building materials
and can lead to indoor air problems
§ TAP can also enter food and water supplies
§ Some TAP can cause cancer
§ Some TAP can cause birth defects (teratogenic);
§ teratogen – mutagen which causes birth defects
§ Some TAP can cause skin & eye irritation and breathing problems
Toxic Air Pollutants (TAP) - Asbestos
§ According to the World Health Organization
(WHO), asbestos can cause mesothelioma (rare
cancer of the lung), as well as lung, laryngeal
and ovarian cancer.
§ The material can also cause asbestosis, or
fibrosis of the lungs – a scarring or thickening of
the lung lining, both of which cause shortness of
breath.
§ Asbestos was used for wall insulation, mixed
with plastic, sealed into floors and built into
cars.
§ It is resistant to heat and corrosion.
https://www.livescience.com/63280-epa-asbestos.html
Toxic Air Pollutants (TAP) - Dioxins
§ Group of chemically-related compounds that are
persistent organic pollutants (POPs).
§ Found throughout the world in the environment and
they accumulate in the food chain, mainly in the fatty
tissues of animals.
§ More than 90% of human exposure is through food, mainly meat and dairy
products, fish and shellfish.
§ Dioxins are highly toxic and can cause reproductive and developmental
problems, damage the immune system, interfere with hormones and may cause
cancer.
§ Burning of municipal and/or hospital waste, backyard burning and automobile
emissions contribute to the release of low levels of dioxins into the
environment.
http://www.who.int/news-room/fact-sheets/detail/dioxins-and-their-effects-on-human-health
Stratospheric Ozone Depleters
§ Chemicals that can destroy ozone in the atmosphere
§ Include chlorofluorocarbons (CFCs e.g. CFCl3, CF2Cl2, C2F3Cl3 and C2F3Cl3),
hydrochlorofluorocarbons (HCFCs), halons and other compounds containing
Cl or Br
§ CFCs are used in air conditioners & refrigerators as coolants, aerosol cans
and fire extinguishers
§ Other ozone depleters are used as solvents in industry
Volatile Organic Compounds (VOCs)
§ Diverse group of organic compounds emitted as gases from certain solids or
liquids
§ Concentration of many VOCs are consistently higher indoors (>10x) than
outdoors
§ Variety of health effects, depending on the individual chemical
§ Many are respiratory tract irritants and carcinogenic
§ Most contribute to photochemical smog
https://www.epa.gov/
Volatile Organic Compounds (VOCs)
Sources
• Paints, paint strippers and
other solvents
• Wood preservatives
• Aerosol sprays
• Cleansers and disinfectants
• Moth repellents and air
fresheners
• Stored fuel and automotive
products
• Hobby supplies
•
•
•
•
Dry-cleaned clothing
Pesticide
Building materials and furnishings
Office equipment, such as copiers and
printers, correction fluid and carbonless
copy paper
• Graphics and craft materials including
glues and adhesives, permanent markers
and photographic solutions
39
Volatile Organic Compounds (VOCs)
Health Effects
§ Eye, nose and throat
irritation
§ Headaches, loss of
coordination and nausea
§ Damage to kidney, liver and
central nervous system (CNS)
§ Some organics may can cause
cancer in animals, some are
suspected or known to cause
cancer in humans
https://www.haywardscore.com/
Pollens
§ Pollen from trees, weeds and grass can cause allergies and hay fever
§ Pollen pollution is expected to increase with global warming as
growing seasons lengthen
https://greenliving.lovetoknow.com/Types_of_Air_Pollution
Molds
§ Mold is a problem affecting indoor air quality
§ Some molds produce toxins that bring on allergies and asthma
§ Molds occur in damp buildings or those with high humidity
§ Air pollution in an urban area is referred to as smog or
industrial smog.
§ Industrial smog is generally worse during the winter
months.
§ Smog is composed of sulfur oxides and particulate matter
§ Industrial smog significant problem in developing
countries due to the lack of pollution-control laws that
developed countries have in place.
How pollutants are formed from
burning of coal and oil. The result is
industrial smog.
Industrial smog in China
© 2017 John Wiley & Sons, Inc. All rights reserved.
§ A brownish-orange haze formed by chemical reactions
involving sunlight, nitrogen oxide and hydrocarbons is
referred to as photochemical smog.
§ Photochemical smog was first noted in Los Angeles in
the 1940s
- Worse in the summer months
§ Ozone is a principal component of photochemical
smog
§ Results in eye irritation, aggravates respiratory illness,
and harms plant tissue
§ Sources include car exhaust, dry cleaners, and bakeries
Photochemical reaction – any
chemical reaction activated by light
Typical Variations with Time in Concentration of Air
Pollutants on a Smoggy Day.
Primary pollutants: NO, CO and
unburned hydrocarbons
Secondary pollutants: NO2 and O3
N2 (g) + O2 (g)
2NO (g) + O2 (g)
NO2 (g) + hn
O (g) + O2 (g) + M
2NO (g)
2NO2 (g)
NO (g) + O (g)
O3 (g) + M
lachrymator – tear producer and
causes breathing difficulties
Formation and composition of photochemical smog
© 2017 John Wiley & Sons, Inc. All rights reserved.
§ A catalytic converter is a unit that fits into
the front part of exhaust system of a
vehicle, close to the engine, to reduce the
emission of gaseous pollutants, such as
carbon monoxide (CO), nitrogen oxides
(NOx) and hydrocarbons (HCs).
https://www.cars.com/auto-repair/glossary/catalyticconverter/
§ Sulfur dioxide and nitric oxide emissions react with
water vapor in the atmosphere to form acids that
return to the surface as either dry or wet deposition.
§ Wet deposition - includes sulfuric acid and nitric acid
in precipitation
§ Dry deposition – dry particles of sulfuric acid and
Acid rain – usually has a pH between
nitric acid that settle out of the air
4.2 and 4.4
§ Acid rain can corrode limestone and marble (CaCO3)
CaCO3 (s) + H2SO4 (aq)
CaSO4 (s) + H2O (l) + CO2 (g)
§ SO2 directly react with CaCO3
2CaCO3 (s) + 2SO2 (g) + O2 (g)
2CaSO4 (s) + CO2 (g)
• Harmful effects:
• Damages statues and buildings
• Contributes to human respiratory diseases
• Leach toxic metals (such as lead and
mercury) from soils and rocks into lakes
used as sources of drinking water
• Harms aquatic ecosystems
• Affects forests in two ways:
• Leaching essential plant nutrients such
as calcium and magnesium from soils
• Releasing ions of aluminum , lead,
cadmium, and mercury, which are toxic
to the trees
Acid Fume Scrubber
liming – a process of adding quicklime
(CaO) to lakes and soils to reduce their
acidity
Ozone Depletion (in purple) Over the South Pole
§ Stratospheric Ozone Thinning is the accelerated
destruction of ozone in the stratosphere by humanproduced chlorine and bromine containing chemicals.
ozone hole – a region of
exceptionally depleted ozone in
the stratosphere over the
Antarctic
https://ozonewatch.gsfc.nasa.gov/
O3 destruction
CFCl3
UV
CF2Cl2
UV
CFCl2 + Cl
CF2Cl + Cl
Cl + O3
ClO + O2
ClO + O
Cl + O2
O3 + O
2O2
Cl catalyzes the reaction
ClO is an intermediate
CHLOROFLUOROCARBONS (CFCs):
§ CFC-12 (CF2Cl2) – used as coolant and
refrigerant
§ CFC-11 (CFCl3) – used to blow holes in
soft plastics
§ CFC-13 (CF2Cl - CFCl2) – cleaning circuit
boards
• Harmful effects:
• Exposure to any amount of UV
radiation increases the risk of skin
cancer and genetic mutations.
• Linked to ocular cataracts and
weakened immunity
• Damage ecosystems, crops, materials
and finishes
Ozone Damage to Grape Leaves
Montreal Protocol
§ A global agreement to protect the
stratospheric ozone layer by phasing out
the production and consumption of
ozone-depleting substances (ODS). It
was finalized in 1987 in Montreal,
Canada.
§ The protocol sets limits on the
production of chlorofluorocarbons
(CFCs), halons and related substances
that release chlorine or bromine to the
ozone layer of the atmosphere.
https://www.ibtimes.co.uk/world-without-montreal-protocolozone-hole-would-have-grown-by-40-by-2013-1503015
53
• Injures organisms
• Reduces visibility
• Corrodes materials
• Metals, plastics, rubber,
fabrics
• Harms the respiratory
tract, and can worsen
existing medical conditions
• Reduces crop productivity
• Involved in acid deposition,
global warming, and
stratospheric ozone
depletion
© 2017 John Wiley & Sons, Inc. All rights reserved.
EFFECTS OF AIR POLLUTANTS
HEALTH EFFECTS:
§ Irritates eyes and respiratory tract
§ Produces chest discomfort
§ Aggravates respiratory conditions such as asthma and
chronic bronchitis
§ Can lead to sore throat, cough, breathing difficulty
OZONE (O3)
ENVIRONMENTAL EFFECTS:
§ Reduces air visibility
§ Stresses plants and reduces their vigor
§ Chronic ozone exposure lowers crop yields
§ Forest decline
§ Greenhouse gas associated with global climate change
EFFECTS OF AIR POLLUTANTS
HEALTH EFFECTS:
§ Reduces the amount of oxygen reaching the body’s organs and tissues.
§ Acute exposure: dizziness, headache, decreased physical performance,
vomiting, nausea and death
§ Chronic exposure: stress on cardiovascular system, fatigue at low levels,
CARBON MONOXIDE
heart attack
(CO)
§ Mental impairment due to high exposure levels (CO poisoning)
ENVIRONMENTAL EFFECTS:
§ Contributes to climate change and global warming (greenhouse gas)
§ Damage to plants and crops exposed
CARBON DIOXIDE
(CO2)
ENVIRONMENTAL EFFECTS:
§ Causes climate change and global warming (greenhouse gas)
EFFECTS OF AIR POLLUTANTS
HEALTH EFFECTS:
§ Acute exposure: lung irritation
§ Chronic exposure: bronchitis
§ Can cause cough, shortness of breath, respiratory infections, and aggravate
asthma
§ Cause chronic lung disease (High exposure)
§ Affect the senses (e.g. ability to smell an odor)
NITROGEN
OXIDES(NOx)
ENVIRONMENTAL EFFECTS:
§ Damage to vegetation (including leaf damage, decreasing growth)
§ Involved in the production of photochemical smog (NO and NO2)
§ Reacts with surfaces
§ Can fade and discolor fabrics and furnishings
§ Harms historical buildings and structures made of limestone and marble
(involved in acid deposition)
§ Contributes to acid rain which can corrode metals
§ Associated with global warming and ozone depletion in the stratosphere
§ Reduces visibility (N2O)
EFFECTS OF AIR POLLUTANTS
HEALTH EFFECTS:
§ Difficulty in breathing
§ Acute exposure: inflammation of respiratory tract, aggravation of
asthma
§ Chronic exposure: emphysema, bronchitis
SULFUR OXIDES
(SOx)
ENVIRONMENTAL EFFECTS:
§ Main contributor to acid rain
§ Secondary main contributor to particulate matter
§ Harms historical buildings, structures, statues and monuments made of
limestone or marble
§ Corrode metals
§ Damage paints, paper, leather
§ Damage to plants and crops (e.g. leaf damage), soils and aquatic life
in lakes
§ Decreasing growth to plants
EFFECTS OF AIR POLLUTANTS
PARTICULAR
MATTER (PM)
HEALTH EFFECTS:
§ Heart disease, irregular heartbeat, reduced lung function, tightness of the
chest
§ Premature death in people with heart or lung diseases
§ Asthma
§ Increased respiratory symptoms (irritation, coughing or breathing
difficulty)
§ Severe respiratory diseases
§ Chronic exposure: bronchitis
ENVIRONMENTAL EFFECTS:
§ Poor visibility
§ Making lakes and rivers acidic
§ Damage to agricultural crops
§ Imbalance of nutrients in coastal waters and river banks
§ Contributes to acid rain
EFFECTS OF AIR POLLUTANTS
HEALTH EFFECTS:
§ Damages the nervous system
§ IQ loss; change in behavior; impacts on learning and memory
§ Risk in high blood pressure, heart disease and kidney disease
§ Reduced fertility
LEAD (Pb)
ENVIRONMENTAL EFFECTS:
§ Body functions of phytoplankton can be disturbed
§ Imbalance in nutrients of soil
§ Damages to internal organs of animals resulting to break of food
chain
• Respiratory system protection from air pollutants:
– Hair in nose filter out large particles
– Sneezing and coughing expel contaminated air
– Cilia - hundreds of thousands of tiny mucuscoated, hair-like structures, line your upper
respiratory tract, continually move back and forth
and transport mucus and the pollutants they trap
to your throat where they are swallowed or
expelled
• Effect of prolonged exposure to air pollutants and tobacco smoke:
– Overload or break down of our natural defenses
– Lung cancer, asthma attack, heart attack, and stroke
– Chronic bronchitis and emphysema, which leads to acute
shortness of breath
Emphysema - a lung
condition wherein the air
sacs, or alveoli, become
damaged which can result to
breathlessness and wheezy
breathing.
• Natural factors that help
reduce outdoor air
pollution
– Settling of particles due
to gravity
– Rain and snow
– Salty sea spray from the
oceans
– Winds
– Chemical reactions
§ Urban buildings – slow wind speed and reduce dilution of
pollutants
§ Hills and mountains – reduce flow of air in valleys, thus
allowing pollutant levels to build up
§ High temperatures – promote chemical reactions leading to
formation of photochemical smog
§ Emissions of VOCs from certain trees and plants – formation
of photochemical smog
§ Grasshopper effect
§ Temperature inversions
Grasshopper Effect or Global Distillation
§ occurs when air pollutants are transported at high
altitudes by evaporation and winds from tropical
and temperate areas through the atmosphere to
the earth’s polar areas;
§ air toxics involved are polychlorinated biphenyls
(PCBs) and dichlorodiphenyltrichloroethane (DDT)
§ happens mostly during winter;
§ explains why pilots have reported seeing dense
layers of reddish-brown haze over the Arctic;
§ also explains why polar bears, sharks, and other
native people in remote arctic areas have high
levels of various toxic pollutants in their bodies
Global distillation – the process
whereby volatile chemicals evaporate
from land as far away as the tropics and
are carried by air currents to higher
latitudes, where they condense and fall
to the ground
Temperature Inversion
§ Normally, warm air and most of the
pollutants it contains rise to mix with
the cooler air above and are
dispersed.
§ Under certain atmospheric
conditions, however, a layer of warm
air can temporarily lie atop a layer of
cooler air nearer the ground, creating
a temperature inversion.
§ Traps air pollutants on ground level
and allows their concentrations to
increase.
Temperature inversion – a deviation
from the normal temperature
distribution in the atmosphere, resulting
in a layer of cold air temporarily trapped
near the ground by a warmer upper air.
• Urban heat islands
– Heat from sunlight heated streets,
rooftops, and parking lots, radiates into
the atmosphere at night
– Heat from human activities is highly
concentrated in urban areas
– These pockets of heat in urban areas
surrounded by cooler rural and suburban
areas, are called heat islands
– Can affect local air currents and weather
conditions
– Cause higher concentrations of particulate
matter called dust domes
This figure shows how temperatures might vary on a
summer afternoon. The city stands out as a heat island
against the surrounding rural areas
© 2017 John Wiley & Sons, Inc. All rights reserved.
• Urban heat islands encourage the formation of a dome of heated air that surrounds an
urban area
– This contributes to the buildup of air pollutants, especially particulate matter
• If wind speeds increase, the polluted air spreads over rural areas
• Cities in valleys are highly susceptible to buildup of pollutants on low wind days
• Increased number of thunderstorms in summer associated with urban heat islands
A dust dome of pollutants forms over a city when the air is somewhat
calm and stable.
When wind speeds increase, the pollutants move downwind from the city.
© 2017 John Wiley & Sons, Inc. All rights reserved.
• At least 2.4 million premature
deaths per year world-wide
– Mostly in Asia
– About 2/3 of these deaths result
from breathing indoor air pollutants
• This refers to the air quality within
and around buildings and
structures.
• Four most dangerous indoor
air pollutants:
– Tobacco smoke
– Formaldehyde
– Radioactive radon-222 gas
– Very small (ultrafine)
particles
• Indoor air pollution can lead to serious health problems
– People in rural areas and developing countries use
solid fuels (wood, coal, peat, and dung) to cook
indoors, with poor or no ventilation
– WHO estimates 1.6 million die annually from indoor
cooking smoke
• Women and children are harmed the most by
indoor cooking
• In developed countries, the most common indoor air
contaminants are radon, cigarette smoke, CO, NO2,
formaldehyde, pesticides, cleaning agents, ozone, and
asbestos
• Viruses, bacteria, fungi, dust mites, pollen, and other
organisms, are frequently found in ventilation ducts
• Health effects:
– Respiratory aggravators
– Potential carcinogen
– Sick building syndrome
© 2017 John Wiley & Sons, Inc. All rights reserved.
• Sick building syndrome (SBS)
– is used to describe situations in
which building occupants
experience acute health and
comfort effects that appear to be
linked to time spent in a building,
but no specific illness or cause
can be identified.
– Eye irritation, nausea,
headaches, respiratory
infections, depression, and
fatigue caused by indoor air
pollution
• The Labor Department
estimates that more than 20
million employees are exposed
to health risks from indoor air
pollution
Homes may contain higher levels of air pollutants than outside air, even near
polluted industrial sites.
© 2017 John Wiley & Sons, Inc. All rights reserved.
• Some alarming facts released by EPA
– Levels of 11 common pollutants generally
are 2 to 5 times higher inside homes and
buildings than they are outdoors, and as
much as 100 times higher in some cases
– Pollution levels inside cars in traffic-clogged
urban areas can be up to 18 times higher
than outside levels
– Health risks from exposure to such
chemicals are magnified because most
people in developed urban areas spend 7098% of their time indoors or inside vehicles
• At greatest risk:
– Smokers
– Children younger than 5 years old
– Elderly
– Sick people
– Pregnant women
– People with respiratory or heart
problems
– Factory workers
• Radon (Rn) is a naturally occurring, colorless,
tasteless, odorless, radioactive gas the comes out of
the ground all around and below us.
• Rn comes from the natural (radioactive) breakdown
of uranium in soil, rock and water and gets into the
air.
• Radon is ubiquitous. It can get into any type of
building, homes, offices, schools, and result in high
indoor radon levels.
• The US-EPA has determined that high levels of
Radon causes lung cancer more often than secondhand tobacco smoke.
How radon infiltrates a house
– Cracks in basement walls or floors,
openings around pipes, and pores in
concrete blocks provide some of the
entries for radon.
How to protect against Radon exposure:
1. Install Rn reduction systems during house
remodeling or when building an addition to
the house.
2. Employ Rn-resistant construction
techniques.
3. Use home Rn detectors.
4. Increase ventilation.
Home Radon Detectors
© 2017 John Wiley & Sons, Inc. All rights reserved.
Learning Objectives
• Enumerate the solutions to reduce threats of air
pollution on human health and ecosystems
• Technology exists to control all of the forms of air pollution
discussed here
– Smokestacks with precipitators, fabric filters, and scrubbers, remove
particulate matter from air
– Careful land-excavation activities reduce the creation of particulate matter
– More fuel efficient automobiles produce fewer polluting emissions
– Sulfur removal from fuel, or using low or no sulfur energy sources, decreases
sulfur pollutants
– Measures taken to increase fuel efficiency and conservation reduce pollution
– Reduction of combustion temperatures reduces formation of nitrogen oxides
– Modification of furnaces and engines and use of catalytic converters can
reduce CO and hydrocarbon emissions
– Careful handling of petroleum products reduces their evaporation and spills
© 2017 John Wiley & Sons, Inc. All rights reserved.
Uncontrolled emissions.
Industrial stacks without
emission control devices
can release substantial
amounts of particulate
matter and other
pollutants.
Electrostatic precipitator. In an
electrostatic precipitator, the electrode
imparts a negative charge to
particulates in the dirty gas. These
particles are attracted to the positively
charged precipitator wall and then fall
off into the collector.
Stacks with emission
controls. Effective
emission control devices
can reduce particulate
matter and other
pollutants.
© 2017 John Wiley & Sons, Inc. All rights reserved.
• Philippine Clean Air Act of
1999
• Provides the policy
framework for the
country’s air quality
management program
• It seeks to uphold the right
of every Filipino to breathe
clean air by addressing air
pollution from mobile and
stationary sources
• Emission trading or cap-and-trade program
• Enables most polluting coal-burning power plants to buy
and sell SO! pollution rights
• Proponents: Cheaper and more efficient than government
regulation of air pollution control
• Critics: allows utilities with older, dirtier power plants to
buy their way out of their environmental responsibilities
and continue polluting
• Makes cheating possible because it is based largely on selfreporting of emissions
• Ultimate success depends on two things: how low the
initial cap is set and how often it is lowered in order to
promote continuing innovation in air pollution prevention
and control
Ways to Reduce
Outdoor Air
Pollution
Ways to
Reduce
Outdoor Air
Pollution
Methods for reducing emissions from
motor vehicles:
Ways to Reduce
Indoor Air
Pollution:
Individuals Matter: What Can You Do?
Pollution
Prevention
Ways to prevent outdoor
and indoor air pollution
over the next 30-40 years
Analyzing Air Pollutants: Air Quality Index (AQI)
An index determined by
calculating the degree of pollution
in the city or at the monitoring
point and includes five main
pollutants:
• Particulate matter
• Ground level ozone (O3)
• Sulfur dioxide (SO2)
• Carbon monoxide (CO)
• Nitrogen dioxide (NO2)
AQI unit: (ug/m3)
https://forum.airnowtech.org/t/aqi-calculations-overview-ozone-pm2-5-and-pm10/168
85
Thank you
Have a great
day ahead.