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Transcript of Effects and Sources of Air Pollutants CE 524 January 2008 Slides noted as AWMA are from:...
Effects and Sources of Air Pollutants
CE 524
January 2008
Slides noted as AWMA are from: Understanding Air Quality from the Air and Waste Management AssociationDo not make copies of these slides for distribution
Major Provisions of 1970 CAAA Established NAAQS
Primary – allows adequate margin of safety to protect public health Secondary – protects public from effects of air pollution
• Plants, animals, visibility, public enjoyment of life & property Set new source performance standards for new stationary sources National Emission Standards for Hazardous Air Pollutants
(NESHAPS) applied to existing and new plants Required states to submit state implementation plans (SIPs)
Method to set AQ standards for air quality regions within state
Air Quality Criteria Based on levels to protect human health
Sensitive members of the population Developed based on relationship between exposure and
short and long-term health and welfare effects Effects are expected to occur when pollutant levels exceed
criteria for specified time period Short-term -- immediate protection Chronic exposure
Pollutant levels cannot legally be exceeded during specific time period in a specific geographical area
National Emission Standards Limit amount or concentration of pollutant
emitted from a source Helps maintain or improve existing air
quality in a region to meet state or local standards
Based on what is achievable with current technology
Basis for Regional Standards Availability of technology Presence of monitoring stations Ability to enforce standards Understanding of synergistic effects of different
pollutants Preparation of diffusion model (predicting
ambient concentrations) Accurate estimates of growth or decline in
industry or population
Criteria AirPollutants
• Carbon Monoxide (CO)
• Hydrocarbons
• Oxides of Nitrogen (NOx)
• Sulfur Dioxide (SO2)
• Particulate Matter (PM10)
• Lead (Pb)
Fundamentals of Air Pollution and Motor Vehicle Emissions
John T. White, EPA
Current NAAQSPollutant Averaging
TimePrimary Standard
Secondary StandardCO
8 hr 9 ppm Same
1 hr 35 ppm Same
NO2 Annual average 0.05 ppm None
SO2 Annual average 0.03 ppm None
24 hr 0.14 ppm None
3 hr None 0.5 ppm
PM10 Annual arithmetic mean
50 g/m3 Same
24 hr 150 g/m3 Same
PM2.5
Added 1997
Annual arithmetic mean
15 g/m3 Same
24 hr 150 g/m3 Same
Ozone 1 hr 0.12 ppm Same
8 hr 0.08 ppm Same
Lead 3 months 1.5 g/m3 same
Hydrocarbons Result when fuel molecules in the engine do not
burn or only partially burn React in the presence of nitrogen oxides and
sunlight to form ground-level ozone, a major component of smog
Ozone irritates the eyes, damages the lungs, and aggravates respiratory problems most widespread urban air pollution problem.
A number of exhaust hydrocarbons are also toxic, with the potential to cause cancer.
Source: EPA 400-F-92-007 August 1994 Fact Sheet OMS-5
Particulate matter
Dispersed airborne solid and liquid particles (specific size criteria in chapter)
Settles out of air at rate which is function of size and weight (measured in micrometer µ = 10-4 cm)
Dust, water vapor, etc Affect health and visibility
ParticulateMatter(PM10)
Also regulating
PM2.5
• PM10 is a general term for tiny airborne particles (under ten microns), e.g., dust, soot, smoke
• Primary sources are fuel-burning plants and other industrial/ commercial processes
• Some are formed in the air
• They irritate the respiratory system and may also carry metals, sulfates, nitrates, etc.
• Some overall decreases seen but trends may be masked by meteorological changes
Fundamentals of Air Pollution and Motor Vehicle Emissions
John T. White, EPA
Health Effects of PM
Particles directly enter respiratory system Particles themselves may be toxic Particle may interfere with mechanisms
which clear the respiratory tract Particle may act as carrier of absorbed toxic
substance 20 to 60% of particles between 1 and 2.5 µm
breathed will penetrate into lungs• Enter deep tissue
SulfurDioxide(SO2)
Sulfur trioxide
• This term is used for a number of compounds containing sulfur
• Primarily caused by burning of coal, oil and various industrial processes
• They can affect the respiratory system
• They react in the atmosphere to form acids, sulfates and sulfites
• Substantial reductions due to controls at the sources and through use of low sulfur fuels
Make up 5 to 20% of total suspended particles
Major damage to materials
Contributes to acid rain
Fundamentals of Air Pollution and Motor Vehicle Emissions
John T. White, EPA
Oxidesof Nitrogen(NOx)
• Nitrogen dioxide is the prominent one (it's the yellow-brown color in smog)
• NOx results from high temperature combustion processes, e.g. cars and utilities
• They affect the respiratory system
• They play a major role in atmos- pheric reactions
• Overall levels unchanged but transportation sources are cleaner
Fundamentals of Air Pollution and Motor Vehicle Emissions
John T. White, EPA
CarbonMonoxide(CO)
• Odorless, colorless gas
• Caused by incomplete combustion of fuel and air
• Most of it comes from motor vehicles
• Reduces the transport of oxygen through the bloodstream
Poses immediate health risk in high concentrations (> 750 ppm)
Hemoglobin has 240 times affinity for CO as for oxygen
• Affects mental functions and visual acuity, even at low levels
• Improvements are being made but there are still problems in some urban areas
Fundamentals of Air Pollution and Motor Vehicle Emissions
John T. White, EPA
Lead(Pb)
• Long known as one of the worst toxics in common use
• Emitted from gasoline additives, battery factories and non-ferrous smelters
• Affects various organs and can cause sterility and neurological impairment, e.g. retardation and behavioral disorders
• Infants and children especially susceptible
• Control of mobile sources has been exceptionally successful
Fundamentals of Air Pollution and Motor Vehicle Emissions
John T. White, EPA
OtherAirPollutants
• Carbon dioxide
• Chlorofluorocarbons
• Formaldehyde
• Benzene
• Asbestos
• Manganese
• Dioxins
• Cadmium
• Still others which are yet to be fully characterized
Fundamentals of Air Pollution and Motor Vehicle Emissions
John T. White, EPA
Categories of Air Pollution
Ambient: air pollution in outdoors Focus of class Regulated by EPA
Indoor Air pollution indoors, buildings EPA studies issues but no federal regulations
Occupational Pollutants in the workplace (mining, chemical operations,
etc) Regulated by OSHA
Personal exposure Persons willful exposure Cigarette, gases, etc
GlobalWarming
• Certain gases in the troposphere absorb some of the infrared radiation reflected from the earth
• Carbon Dioxide is the major one (50%).
• Others include methane (18%) and CFCs (14%). CFCs also are responsible for destroying the stratospheric ozone layer
• The United States produces over 20% of the world's "greenhouse" gases
Fundamentals of Air Pollution and Motor Vehicle Emissions
John T. White, EPA
TheExtentofAirPollutionToday Overall, 54 million metric
tons from mobile sourcesin 1990 (43% of total)
Mobile SourcesStationarySources
CO
VOCs
NOx
SO2
Lead
PM10
Fundamentals of Air Pollution and Motor Vehicle Emissions
John T. White, EPA
Who isAffected byAir Pollution?
63
22
9
19
15
Ozone CO NO2 PM10 SO2 Lead
Millions of people living in counties with air quality that exceeds each NAAQS (1990 data)
Over 74 million people are subjected to high levels of at least one of these pollutants
Fundamentals of Air Pollution and Motor Vehicle Emissions
John T. White, EPA
World wide
WHO indicates that 2.4 million people die from causes directly attributable to air pollution
More than for car accidents
Visibility
Although not a pollutant, visibility is a major pollution concern
Haze Smog
Air Toxics
Get stuff from EPA http://epa.gov/otaq/toxics.htm
When is it a problem
Classified as pollutant once their presence results in damage to humans, plants, animals or materials
Concentration 1 volume of gaseous pollutant = 1 ppm106 volumes (pollutant + air)
0.0001 percent by volume = 1 ppm
Non-attainment areas