Air Quality Issues: Air Pollution, Indoor Air Pollution, Acid Deposition, Greenhouse Gases
EVPP 111 Lecture
Dr. Largen
Air Quality Issues
Air Pollution
Indoor Air Pollution
Acid Deposition
Greenhouse Gases
Air Quality Issues
Air quality
can be degraded by
- natural events
- volcanic gases & particulate emissions
- dust from wind-borne soil particles
- gases from decomposition of organic material
- anthropogenic (activities of humans)
- automobile emissions
- industrial process emissions
Air Quality Issues
Air quality
degradation caused by human activities is considered to be air pollution
- related to
- the number of people living in an area
- the kinds of activities the people are involved in
- when we put material into the air we don’t get rid of it
- we just dilute it and move it out of the immediate area
Figure: Air Quality
Air Quality Issues
air pollution results in
reduced aesthetic value of scenery
human health problems
damage to ecosystems
- due to harmful effects on plant and animal life and reduced water quality
international conflicts
damage to structures
increased costs
- resulting from attempts to meet air quality standards
Air Quality Issues
air pollution incident harms human health, an example
occurred in the valley town of Donora, PA in 1948
pollutants from zinc plant and steel mills became trapped in the valley
- due to a temperature inversion
- forming a dense fog
within five days
- 17 people died
- 5,910 people became ill
Air Quality Issues
air pollution
extremely poor air quality common in megacities of developing countries
- such as
- Mexico City, Beijing, Seoul, Cairo
- due to
- open fires
- large numbers of poorly maintained vehicles
- poorly regulated industrial plants
Air Quality Issues
air pollution
air pollutants in the US accumulate due to the predominant west to east winds
- as an air mass moves from west to east
- each population center adds its pollutants to the total load
Figure 17.3: Accumulation of Air Pollutants
Air Quality Issues
Primary air pollutants
globally, 5 major types of materials
- are released into atmosphere in sufficient quantities to pose a health risk
- these are called primary air pollutants
- carbon monoxide
- hydrocarbons
- particulates
- sulfur dioxide
- nitrogen compounds
Figure: Sources of Air Pollutants
Air Quality Issues
Primary air pollutants
can interact with one another in the presence of sunlight to form
- secondary air pollutants
- ozone
- other PANs (peroxyacyl nitrates)
Air Quality Issues
carbon monoxide (CO)
produced when organic materials (gasoline, coal, wood) are incompletely burned
single largest source is automobiles
- automobile CO emissions have ¯
- increased fuel efficiency
- use of catalytic converters
- emissions still a problem because of
- increase in number of automobiles
- increase in number of kilometers driven
next largest source of CO is smoking tobacco
Air Quality Issues
carbon monoxide (CO)
is not a persistent pollutant
- natural processes convert it to other compounds that are not harmful
- air can be cleared of CO if no other new CO is introduced to atmosphere
is toxic to humans and other animals
- because it is strongly attracted to hemoglobin in blood
- which will take up CO nearly 250 times more rapidly than O2
Figure: Sources of Air Pollutants - Carbon Monoxide
Air Quality Issues
Hydrocarbons (HC)
produced by evaporation from fuel supplies or from incomplete combustion of fuels
are a group of organic compounds consisting of carbon and hydrogen atoms
sources of HC emissions
- major
- internal combustion engine
- additional
- oil refineries and other industries
Air Quality Issues
Hydrocarbons (HC)
modifications to automobile engines help reduce HC emissions
- recycling some gases through the engines
- using higher oxygen concentrations in the fuel-air mixture
- using valves to prevent escape of gases
- catalytic converters burn exhaust gases more completely
Air Quality Issues
Particulates
minute pieces of solid materials dispersed into the atmosphere
produced by a variety of processes
- smoke particles from fires
- asbestos from brake linings and insulation
- ash from industrial plants
- farming
- construction
- desertification
- volcanoes
Air Quality Issues
Particulates
can produce variety of problems
- "visual" pollution caused by smoke
- affect health by acting as centers for the deposition of moisture and gases
- respiratory problems
- miners & workers exposed to dust
- asthma
- cancer from carcinogens such as asbestos
- sulfuric, nitric and carbonic acids
Figure: Sources of Air Pollutants - Particulates
Air Quality Issues
Sulfur dioxide (SO2)
produced when sulfur-containing fossil fuels are burned
- organisms from which coal and oil were produced contained sulfur, some of which was incorporated into the fossil fuel
reacts with water and other materials to form sulfur-containing acids
- when those acids become attached to particles that are inhaled
- they are very corrosive to lung tissue
Air Quality Issues
Sulfur dioxide (SO2), some incidents
in 1306, Edward I of England banned the burning of "sea coles" in the city of London
- these were coals from the seashore that were high in sulfur content
Air Quality Issues
Sulfur dioxide (SO2), some incidents
in 1952, London was covered with a dense fog for several days
- during which time the air didn’t mix because of temperature conditions
- factories continued releasing smoke & dust
- producing "smog"
- within a few weeks 4,000 people died
- deaths attributed to high level of sulfur compounds in the smog
Figure: Sources of Air Pollutants - Sulfur Dioxide
Air Quality Issues
Nitrogen oxides (NO and NO2)
produced when N & O in air react with one another as a result of combustion
several compounds have N & O combinations
- most common are
- nitrogen oxide (NO)
- nitrogen dioxide (NO2)
- mixture of NO and NO2 is called NOx
nitrogen oxides are noteworthy because of the role they play in production of
- secondary air pollutants (photochemical smog)
Air Quality Issues
Nitrogen oxides (NO and NO2)
primary source of nitrogen oxides is the automobile engine
- catalytic converters help reduce amount of nitrogen oxides released from the internal combustion engine
- increased automobile traffic has resulted in significant NOx levels in many metropolitan areas
Figure: Sources of Air Pollutants - Sulfur Dioxide
Air Quality Issues
Secondary air pollutants
compounds that result from interaction of various primary air pollutants
photochemical smog
- a mixture of pollutants resulting from interaction of nitrogen oxide with UV light (sunlight)
two secondary air pollutants, most destructive components of photochemical smog
- ozone
- peroxyacyl nitrates (PANs)
Air Quality Issues
photochemical smog
ozone & peroxyacyl nitrates (PANs)
- both are excellent oxidizing agents
- react readily with many other compounds, including those in living systems, causing destructive changes
- ozone
- destroys chlorophyll in plants
- injures lung tissue in animals
- PANs
- eye irritants
Air Quality Issues
Typical photochemical smog event
morning traffic produces lots of NO
N2 + O2 ®
2NO
NO reacts with molecular oxygen from atmosphere to form NO2, gives photochemical smog its reddish-brown haze
later in morning, NO2 reacts with UV in sunlight to form atomic O
molecular oxygen in atmosphere reacts with atomic oxygen to form ozone
O2 + O ®
O3
Figure: Urban smog
Air Quality Issues
Typical photochemical smog
some areas have more trouble with photochemical smog than others because of their climate and geography
Los Angeles, Salt Lake City, Phoenix
- each of which is ringed by mountains
- prevailing winds are from west
- cool air flows into valley, pushes warm air up, becomes trapped between two layers of cool air, creates thermal inversion
- cool air can’t move out of valley because of mountains
Figure 17.7: Thermal inversions
Figure: Thermal inversions
Figure: US Air Pollution Trends
Figure: Air Pollution Reduction
INDOOR AIR POLLUTION
- 1990 - EPA placed indoor air pollution at the top of the list of 18 sources of cancer risk. (People spend 70-98% of time indoors)
- Cigarette smoking is the single most preventable cause of death and suffering among adults. Kills 8200 people/day - number is expected to triple by 2050.
Sick Buildings - EPA states at least 1/5 of all buildings in US are "sick".
LDCs also have indoor air pollution because of burning fires in open non-vented indoor areas. Partially as a result, respiratory problems are a major health problem in LDCs.
EFFECTS OF AIR POLLUTION ON LIVING ORGANISMS AND MATERIALS
Damage to Human Health
Prolonged Exposure - Prolonged exposure can lead to breakdown of natural defenses, leading to lung cancer, asthma, chronic bronchitis, and emphysema.
Deaths - US estimates of annual deaths = 7,000 -180,000. If include indoor air pollution, 150,000 - 350,000.
- Costs - According to EPA and American Lung Association, air pollution costs US minimum of $150 Billion annually in health care and lost worker productivity, with $100 Billion of that related to indoor air pollution.
Air Quality Issues
Acid deposition
the accumulation of potential acid-forming particles on a surface
acids can result from
- natural causes
- vegetation
- volcanoes
- lightning
- human activities
- burning coal
- internal combustion engine
Air Quality Issues
Acid deposition
combustion processes produce sulfur dioxide and oxides of nitrogen
- which are converted to sulfuric acid and nitric acid
- in the presence of water, and oxidizing agents
- such as ozone, hydroxyl ions, hydrogen peroxide
Figure 17.9: Acid Deposition
Air Quality Issues
acid-forming reactions are classified as
wet (precipitation)
reactions occur in the atmosphere
acids come to earth in precipitation
acid rain
acid dew
acid snow
dry (deposition)
particles related to acid settle onto a surface
reactions occur when these materials mix with water
Air Quality Issues
Acid rain
is the collective term used to refer to all the acid forming processes
- regardless of how the acids are formed or deposited
- wet or dry
pH of "normal" rain
- between 5.6 and 5.7
- slightly acidic due to
- formation of carbonic acid when carbon dioxide reacts with atmospheric moisture
Figure: Typical pH Values
Air Quality Issues
Acid rain
scope of the problem
- global
- reports of high acid rain damage
- Canada, England, Germany, France, Scandinavia, US
can have concentration of acid a thousand times higher than normal
- a rain in NH, 1969, pH=2.1 ~ lemon juice
- rain in NE US and Ontario has average pH=4.0-4.5
Figure: US Acid Precipitation
Air Quality Issues
Acid rain causes damage to
human-made materials
- buildings and monuments made of limestone can be eroded when
- sulfuric in acid rain reacts with calcium carbonate
- metal surfaces can be corroded
ecosystems
Air Quality Issues
Acid rain causes damage to
ecosystems
- terrestrial
- forests in NE US have sustained significant tree death and reduction in tree vigpr
- aquatic
- as lakes become more acidic there is progressive loss of many kinds of organisms
- healthy lakes have pH ~6.0
- lakes with pH~4.5 are nearly sterile
Figure: Acid Rain Damage
Global Warming & Climate Change
Emission of gases to the atmosphere
increasing due to human activities
- activities
- burning fossil fuels
- deforestation
- industrial processes
- gases
- carbon dioxide
- chlorofluorocarbons
- nitrous oxide
- methane
Global Warming & Climate Change
During 1980s, scientists became concerned that the earth may be getting warmer
in past 100 years, earth’s
- average temperature has
0.3-0.6 °
C
- sea level has
10-25cm
- 1999 was warmest year on record
strong correlation between temperature increase and amount of "greenhouse gases" in atmosphere
human activity increases amounts of these gases
changes in global climate patterns are occurring
Global Warming & Climate Change
Areas of concern related to global warming and climate change
human health effects
rising seas levels
disruption of water cycle
changing forests and natural areas
challenges to agriculture and food supply
Global Warming & Climate Change
what causes global warming?
several gases in the atmosphere are
- transparent to light
- allowing sunlight to penetrate atmosphere and be absorbed by earth’s surface
- absorb infrared radiation
- sunlight energy that is absorbed by earth’s surface is re-radiated as infrared radiation
- which is absorbed by the gases
Global Warming & Climate Change
what causes global warming?
gases in the atmosphere
- allow heat to enter (as sunlight) but retard the loss of heat
- producing a process called the greenhouse effect
- the atmospheric gases contributing to the effect are called greenhouse gases
Global Warming & Climate Change
what causes global warming?
greenhouse gases
most important are
carbon dioxide
chlorofluorocarbons (CFC)
methane
nitrous oxide
Figure: The greenhouse effect
Figure 17.17: Greenhouse effect
Figure: The Greenhouse Effect (#2)
Global Warming & Climate Change
Carbon dioxide most abundant greenhouse gas
produced as waste product of
- cellular respiration in living organisms
- energy production
atmospheric levels have been increasing steadily for 40 years
reducing emissions of this gas would be a step toward slowing global warming
- increase efficiency of energy usage
- increase amount of carbon dioxide removed from atmosphere
- via photosynthesis which requires it
Figure: Carbon dioxide concentration in Hawaii
Figure: Carbon dioxide levels
Global Warming & Climate Change
Methane
enters atmosphere primarily from biological sources
- released by several bacteria abundant in wetlands and rice fields
- released by bacteria in guts of termites and ruminant animals (such as cattle)
- some enters from fossil fuel sources
Global Warming & Climate Change
Nitrous oxide
minor component of greenhouse gases
enters atmosphere primarily from fossil fuels and fertilizers
Global Warming & Climate Change
Chlorofluorocarbons
present in atmosphere in minute quantities but are extremely efficient greenhouse gases
- about 15,000 times more efficient at retarding heat loss than is carbon dioxide
are entirely the result of human activity
refrigerant gases in refrigerators and air conditioners
cleaning solvents
propellants in aerosol containers
expanders in foam products
Global Warming & Climate Change
Chlorofluorocarbons
in the 1970s, were linked to the depletion of the ozone layer in the upper atmosphere
- located in the stratosphere
- absorbs most ultraviolet radiation that is potentially damaging to life
reactive chlorine is released when CFCs are destroyed after reaching the upper atmosphere
- can then enter into reactions that deplete ozone in the upper atmosphere
- leading to an increase in amount of UV radiation reaching earth
Figure: Ozone destruction
Global Warming & Climate Change
Chlorofluorocarbons
the Antarctic Ozone Hole
- first reported in 1985
- occurs in spring
Figure: South pole ozone depletion
The End