Air Pollution Effects on the Environment
Including Humans
IAA Monthly Lectures
November 13, 2008
Rockville, MD
Bahram Momen
Environmental Science & Technology Dept.
University of Maryland, College Park
bmomen@umd.edu
301 405 1332
Air Pollution: Indoor and Outdoor
I. Indoor Air Pollution (IAP)
• Among top five risks to public health
• Includes home & work environments
• Up to five times worst than outdoor pollution
• Worst in the developing countries
• In developed countries people spend much time indoor
• Air conditioning & heating with closed windows??
• 30% of buildings have IAQ (indoor air quality)
problems (known as Sick Building Syndrome or SBS)
• 25% of workers have problems with work environment
affecting quality of their work
• Associated pollutants:
- Particulates, Microbes, Chemicals
- Defining the relative impacts of each source is difficult due
to individual genetic susceptibility and interactive effects
of multiple pollutants
- Difficult to come up with acceptable levels for all
- Frequently the effects are considered through
retrospective or anecdotal evidence
Sources of IAP
• Human activities and climate controls designed for comforts
and/or efficiency
• Energy efficient buildings
• Reduced air exchange
• Elevated humidity and temp. in microzones (e.g., bathrooms
and kitchen)
- increases mold growth
- increases formaldehyde emission from manufactured
material
• Fossil fuel burning appliances, humidifiers, pesticides,
construction material, etc.
Kinds of IAP
1. Volatile Organic Compounds (VOC)
•Contain carbon, hydrogen, oxygen, fluorine, chlorine,
bromine, sulfur, nitrogen, etc.
•May be very potent persisting indoor for a long time
•Are easily vaporized at room temp. releasing noxious vapors
•Are contained in household products for cleaning,
disinfecting, degreasing, waxing, cosmetics, air fresheners,
dry-cleaned fabrics
•Research is lacking on short- and especially long-term
effects of individual pollutants let alone their interactive
effects
2. Pesticides
•In the US, 80% of exposures to pesticide occurs indoor and
up to 12 different pesticides can be found in a single home
•75% of the US households report indoor use of at least one
pesticide/yr
•They include insecticides, termiticides, rodenticides,
fungisides, microbial disinfectants formulated as sprays,
foggers, liquids, sticks or powders
•They aim to kill, and thus, are highly toxic
•Exposure to pesticides accounts for about 80,000 poisoning
of children /yr due to ingestion, but inhalation and dermal
exposure also occur
•Health risks: systematic illness, organ damage, respiratory
irritation and disease, neurological disorders, headaches,
nausea, dizziness
3. Construction material and furnishings
• Asbestos historically used for insulation and fire-retardant
(floor and ceiling tiles, counter tops, pluming, etc.)
- its use has been banned and it is continued to be removed
from older buildings during reconstruction or remodeling
- If in good condition and undisturbed not a major risk?
- Aerosolized fibers are very small and when respired can
damage the lungs and abdominal lining leading to
irreversible scarring and cancer
3. Construction material and furnishings …
• Carpeting and related material (adhesives, padding) emit
VOC and cause eye, nose, throat irritation, headaches,
rashes, coughing, fatigue, shortness of breath
- can also act as a sink for pesticides, dust mites, molds that
are hard to clean and remove by vacuuming
- fabrics, paints, furniture (pressed wood products) emit
formaldehyde
-- a carcinogen absorbed through nose and skin
-- target levels < 0.1 ppm (some states 0.05 ppm)
-- mobile homes are of particular concern because of high
emitting amount and small interior space
3. Construction material and furnishings …
Possible remedies:
• High ventilation
• Low humidity
• Low temp.
• Selection of low emitting material
• Application of water repellant finishes
• Older material have lower emission due to natural decay
of toxins overtime
4. Combustion Products
•Oil, gas, kerosene, wood, and coal (burned by appliances,
space heaters, fireplaces, gas or wooden stoves)
- If not properly vented, installed, or maintained, emit CO,
NO2, particle and chemical irritants
•CO (colorless, very dangerous)
- Kills about 500 Americans /yr (symptoms: headache, chest
pain, dizziness, weakness, nausea, vomiting, confusion
•NO2; Colorless, irritant of the mucous membranes of the
eye, nose, and throat
- High exposure causes respiratory irritation, shortness of
breath, respiratory infection and lung diseases
4. Combustion Products …
•Tobacco smoking, about 46,000,000 American smoke
- Contains 4000 chemicals, 200 known toxins, 69 known
carcinogens
- 75% of nicotine ends up in the atmosphere
- Secondhand smoke contains higher concentration of toxic
and carcinogens than smoke inhaled directly
- Kills 3,000 non-smoking Americans through lung cancer
35,000 through heart disease
150,000 to 300,000 children < 18 yr through respiratory
track infection
- Children exposed to secondhand smoke are at higher risk
of pneumonia, ear infection, bronchitis, coughing,
wheezing, and asthma
5. Lead
• In the late 20th century, the greatest environmental harm to
children’s health in the US
• Used widely in pluming material, gasoline, and paints until
banned in 1960
• Can be transferred indoor from outdoor via dust, shoes,
clothing, and pets
• Lead particulates may be inhaled or ingested to be
absorbed into the blood to be distributed to soft tissues
and bone and eventually affect every system in the body
• At levels > 80 mg /dL of blood convulsion, coma, and death
can occur
• Levels as low as 10 mg /dL can impair mental and physical
development leading to lower IQ, ADD, increased
behavioral problems, and damage to central nervous
system, kidneys and blood cells
6. Radon
• A colorless, odorless, radioactive gas released from natural
decay of uranium, a common component of rocks, soil, and
water
• Radon enters homes through cracks, drains, and wells
• Once inside can be trapped and increased in concentration
while undetected
• Its inhalation can cause lung cancer and death
• Listed as the second leading cause of lung cancer in the US
• About 21,000 deaths /yr can be prevented by addressing
radon exposure (by individual blood testing
- home radon reduction systems (by 99%) are available
7. Biological Pollutants
• Bioaerosols are biological agents (e.g., bacteria, viruses,
mold, mites, cockroach particles, pollen, animal dander and
saliva) transmitted by air
• Associated with allergies and asthma that have significantly
increased worldwide during the last 30 yrs
• Can persist in dust particles and animal droppings and/or
proliferate in humid micro zones until becoming airborne
• Natural breeze, air conditioning, system humidifiers, and
active movements aid in the transfer of bioaerosol
7.1. Mold
• Allergic reaction caused by direct exposure to spores and
cell wall components or from the production of metabolites
(microbial volatile organic compounds, mycotoxins)
• Even nonviable mold fragments can initiate allergic reaction
• Threshold levels are unknown and appear to depend on the
type of mold and the individual
7.2. Endotoxin, Bacteria, and Viruses
• Bacteria grouped into 2 classes depending on the chemical
composition of their cell walls: Gram negative and Gram
positive
- Gram negative: have outer cell wall that contain LPS
(lipopolysacharide - - fat and carbohydrate)
-- as intact or fragmented bacterial cell-walls can cause
adverse effects in humans and animals including fever,
blood clothing, alteration of the behavior of white blood
cells (reason to call it as endotoxin)
-- found in household dust, easily airborne and inhaled to
cause lung problems
• Transmitted by sneezing and coughing,
water use, direct contact or use of
humidifiers, ventilation of heating &
cooling systems
• Infections increases in winter due to
more indoor, closed door human
activities
• The US population suffers 1 billion colds/yr
• Each season about 50 million Americans contract the flue
and about 20,000-40,000 die/yr
7.3. Animal allergens
•Tiny scales of skin constantly shed from animals (e.g., pets,
rats, mice) and airborne
•Animal urine and saliva proteins
•15% of American allergic to cats or dogs and 2 million with
cat allergies still keep cats
7.4. Arthropod allergens
•House dust mites:
- microscopic organisms related
to spider and ticks
- major pollutants of indoor air
- cause non-seasonal allergy in
about 20,000,000 Americans
- present in all homes, in the
house dust, bedding, and carpeting
- Feeding on dead human skin and thrived
under increased humidity
•Cockroaches
- highly adaptable to extreme
conditions,
- can be found everywhere
(98% of urban homes)
- cause asthmatic allergies
8. Plant allergens
•Outdoor allergens such as pollen
can enter indoor via pets, shoes,
personal objects, open windows
and doors
•About 35,000,000 American suffer
Factors affecting indoor pollution exposure
•Identification of the source and level
•Duration of exposure
•Environmental maintenance
•Assessing interactive effects of multiple pollutants
1. Exposure reduction
• Education
• Removal of the source
• Following label information of household products and
reduce their use
• Ensure fuel-burning appliances are properly installed,
operated, maintained (ventilated, serviced, etc.)
• Reduce humidity
2. Building maintenance and operation
•Properly installed and maintained heating, cooling and
their ventilation systems can reduce indoor pollution and
its transfer from outdoor and vise versa
•Use of fungicide paint
•Use of air purification systems
3. Building design
•Sustainable and green building design
•Sub-slab or plastic sheeting systems to remove radon
•Crack and joint sealing
•20 cubic feet per minute of outdoor air per person
Sources of IAP In Developing countries …
• Heating and cooking using biomass (wood,
charcoal, crop residue, dung) and coal
combustion
• Leading cause of mortality and disease , mostly
the poor
• Disproportionately affecting women and
children
Improvements are easy and inexpensive…
• Improving stoves for more efficient
combustion and better ventilation
• Appropriate chimney
• Separating kitchen from living areas
• Better education on oven use
• Using Solar Ovens
(http://www.solarovens.org/)
> no photo-cell
> clean heat
> for regions with abundant solar radiation
> with or without reflectors
- less than US $200
- 210-320 oF depending on the sun’s angle
and use of reflectors
II. Atmospheric Pollution
• Major public, scientific, and policy concern, subject of
extensive research
• Atmosphere: a mixture of gases and particles
• Air pollutant: any substance in air that, in high enough
concentrations
> harming ecosystems and their components (human,
animals, vegetation, etc.), or materials (e.g., buildings,
monuments, etc.)
> reducing visibility???
• Early accounts due to smoke from burning wood and coal as
well as lead mining in ancient Greece and Rome
• King Edward I of England in the 13th century prohibited use
of sea coal that produced soot and sulfur dioxide over
London
• Industrial revolution and fossil fuel burning increased air
pollution exponentially
• In 1948, the first Air pollution disaster in the US occurred
and 20 lives were lost as a result of industrial pollutants
trapped in very stable air over Donora, PA
• In 1952, a week coal burning & stagnant air resulted in
severe smog over London to kill 12,000 in 3 months
• All major metropolitan areas now suffer, especially in
valleys (e.g., Mexico City) or along coastal mountain ranges
(e.g., Los Angeles)
• Air pollutants can be found throughout the troposphere but
those closer to the earth surface with high concentrations
are of primary concerns
•Pollutant concentrations depend mostly on
- total mass emission
- Atmospheric condition that affects the pollutants fate and
transport, e.g.,
-- warm, sunlit air + NOx + carbohydrates (O3 formation)
- Vertical and horizontal air movements (dry deposition)
- Rain and snow (wet deposition, acid rain)
• Effects on human and ecosystem health: not fully
understood
• Costs: associated with prevention, removal, treatment, etc.,
not fully understood
Primary Atmospheric Pollutants
The US-EPA designates 6 types of primary pollutants for
regulatory purposes:
•Carbon monoxide
•Hydrocarbons
•Particulate matter
•Sulfur dioxide
•Nitrogen oxides
•Lead
•Carbon dioxide (CO2)???
• Carbon monoxide (CO)
 Highly poisonous, colorless, odorless
 Exists in urban air
 Constitutes 60% of primary pollutants
 50% produced from incomplete combustion
of fossil fuels in cars and trucks
 Is part of cigarette smoke
 Has few natural sources
 Relatively stable but short-lived in the atmosphere
(converts to CO2)
 Is decreasing due to increasing fuel efficiency and using
oxygenated gas and ethanol
• Hydrocarbons (HCs) or Volatile Organic Carbons (VOCs)
Methane (CH4) the most abundant of HCs),
a green house gas produced by farm waste,
garbage decomposition, cows
VOCs are non-methane HCs including:
- Benzene and their derivatives such as
formaldehyde
- HCs contributes to O3 production
- Large portion produced by anthropogenic activities
(fossil fuel burning, gasoline evaporation)
- Produced naturally from decomposition
of organic matter and some plants
(pines, creosote bushes)
•Particulate matter
 Includes solid particulates or liquid droplets small enough
to remain suspended in air (soot, smoke, dust, asbestos
fibers, pesticides, S and N compounds, Hg, Fe, Cu, Pb)
 They can reach stratosphere and block sunlight –cooling
effect
 In the troposphere can lead to respiratory illnesses, acid
rain, decreased visibility, etc.
 In the US about 60% come from roads and transportation
25% agriculture, forestry, and fire
•Sulfur dioxide
 90% of its emission comes from fossil fuel
(coal, gasoline, etc.)
 Ore smelters and oil refineries are other sources
 Causes respiratory illness, acid rain with adverse effects
on all components of the ecosystem and buildings
•Nitrogen oxides (NOX)
Formed mainly from N2 and O2 during high-temperature
combustion of fossil fuel in engines (catalytic converters
are used to reduce NOx)
Contributes to heart and long problems and acid rain and
O3 formation
 Natural sources include metabolic activities of soil
bacteria
•
Lead
 Highly toxic
 From leaded gasoline and paint in the past
Secondary Pollutants
•Formed during chemical reaction between primary
pollutants and other atmospheric constituents such as
water vapor
•Reactions generally occurs in sunlight to produce
photochemical smog
•Composed mainly of O3
> Favorable condition for O3 formation: air temp exceeding
32 oC, low wind, intense radiation, low precipitation
> Many US cities exceed the EPA standard (80 ppb for one
hour per day averaged over 3 years)
> Not limited to urban areas anymore
> Affects all living things (humans, plants, etc.)
Other pollutants
•EPA has identified about 188 other chemicals that are
considered to be hazardous air pollutants (HAPs)
Pollutants with Radioactive Effects
•Green House gases:
CO2, CH4, N2O, CFCs, H2O, and O3
I. Green house gases (CO2, CH4, etc.)
- increased CO2 not considered pollution by some
due to an incorrect perception that increased CO2
can enhance vegetation growth
Sources:
• Natural: biological and chemical processes
• Anthropogenic: fossil fuel combustion
•Sources: Are many, including
- May natural and/or anthropogenic:
Cars, industry, wind erosion of soil, natural processes (e.g.,
volcanic ash), agriculture, forestry practices, development)
- In both gases and particulate forms from fixed or mobile
sources
II. Acidic deposition (wet & dry?)
• Sulfur compounds:
regulations have decreased their emissions &
depositions(?)
• Nitrous Oxides (NOx):
les strict regulation for N than S (?) and thus, N deposition
is gaining importance in acidification
Sources:
• Natural: biological decay
• Anthropogenic: fossil fuel combustion
III. Ozone (O3), two contrasting issues
1. Decreased in the stratosphere (15-50 km) where
needed to shield against harmful solar rays
- decreased mostly by CFCs whose production has
been phased out (an international successful effort)
2. Increased in the troposphere (0-15 km) where
adversely affects all living things!
- increased mostly by photochemical reaction of Nox
and VOC
Concerns
• Extent of anthropogenic vs. natural pollution
• Complexities involved in studying and documenting the
effects of even individual air pollutants
OZONE
- decrease
+ increase
plant cells via stomates
- cell-wall
oxidizes & degrades
large molecules
N release
N moves to:
wood?
roots?
rhizosphere?
N saturation?
N resynthesis
+ surface area &
surface tension
costly
+ Rs
beneficial
+ An
- stomatal
cond.
+
+ [cellular]
- An
- leaf area
+ foliar C:N
herbivory?
litter C:N?
decomposition?
elasticity
- w, s,
-
+
& TLP
GROWTH
+
p
• Multifaceted effects especially on
> Ecosystem & human Health
- effects of CO2, O3, N, acid rain, etc.
> Sustainable economic development
> Sustainable industrial development
> Climate Change
• Links among pollutants
• Individual and interactive effect of pollutants
on the systems affected
> e.g., reversal of some short-term, positive
effect of elevated CO2 on vegetation by
elevated tropospheric O3
> e.g., synergistic effect of O3 & N deposition on N
saturation, that can affect water quality & endanger
ecosystems stability
> complexities involved in setting standards
Stratospheric Pollution
•CFCs, O3, UVB, and 1987 Montreal Protocol
Cutting edge research
• Scientists at MIT have found that
> nano-structural organization of concrete determines its
strength not the material itself
- concrete used in developed and developing countries
account for 5-10% of the worlds total CO2 emission
- using Mg instead of Ca can provided same nanostructural strength under lower temp. leading to
producing concrete with 10% less CO2 emission
• Geo-thermal energy currently being employed in California,
Hawaii, Utah, and
Nevada
• MIT scientists are also working on a more efficient use of
geo-thermal energy with initial optimistic results
• Scientists (Farrel et al. Science, 2006) have shown drastic
benefit from transition to cellulose-based from cornedbased ethanol
• Sugar cane/corn Bio-fuel, palm oil
> advantages/disadvantages in terms of
- energy cost to produce
- fertilization
- clear-cutting tropical forest
• Wind, solar, hydro-energy
Concluding Remarks
•Air pollutants are
> by-product of increased population, standard
of living, & industrialization
> anthropogenic cause of global warming &
climate change
> more expensive, and often impossible to
eliminate or reduce, for developing countries in
need of sustainable development, technology
transfer, etc.
Concluding Remarks
•Air pollutants may be generated locally but they
> do not stay local
> do not respect human-set boundaries and borders
> affect polluters and non-polluters alike
• “We are not inherited the natural resources from
past generations; rather we are borrowing them
from our children”
• “The nature will take care of itself, but it does not
guarantee that we will stay a part of it”