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Human Impact on the Atmosphere Chapters 16 Air Pollution

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1 Human Impact on the Atmosphere Chapters 16 Air Pollution
Advanced Placement Environmental Science

2 Pollution Thorpe, Gary S. , M. S. , (2002)
Pollution Thorpe, Gary S., M.S., (2002). Barron’s How to prepare for the AP Environmental Science Advanced Placement Exam The term “Smog” (smoke and fog) was first used in 1905 to describe sulfur dioxide emission In 1952, severe pollution took the lives of 5000 people in London “It isn’t pollution that’s harming the environment. It’s the impurities in our air and water that are doing it.” Former U.S. Vice President Dan Quayle 97annual.html

3 The Clean Air Act Congress found:
• Most people now live in urban areas • Growth results in air pollution • Air pollution endangers living things It decided: • Prevention and control at the source was appropriate • Such efforts are the responsibility of states and local authorities • Federal funds and leadership are essential for the development of effective programs The Clean Air Act

4 Clean Air Act Originally signed 1963
States controlled standards 1970 – Uniform Standards by Federal Govt. Criteria Pollutants Primary – Human health risk Secondary – Protect materials, crops, climate, visibility, personal comfort

5 Clean Air Act 1990 version 1997 version
Acid rain, urban smog, toxic air pollutants, ozone depletion, marketing pollution rights, VOC’s 1997 version Reduced ambient ozone levels Cost $15 billion/year -> save 15,000 lives Reduce bronchitis cases by 60,000 per year Reduce hospital respiratory admission 9000/year

6 Pollutants Categories
1. Primary Pollutants- released directly from the source. 2. Secondary Pollutants: a) modified to a hazardous form after they enter the air or b) are formed by chemical reactions as components of the air mix and interact.

7 Pollution Categories Fugitive Emissions are caused by soil erosion, strip mining, rock crushing and building construction. In US, fugitive dust adds up to 100 million metric tons/year.

8 Outdoor Air Pollution

9 Major Sources of Primary Pollutants
Stationary Sources Combustion of fuels for power and heat – Power Plants Other burning such as Wood & crop burning or forest fires Industrial/ commercial processes Solvents and aerosols Mobile Sources Highway: cars, trucks, buses and motorcycles Off-highway: aircraft, boats, locomotives, farm equipment, RVs, construction machinery, and lawn mowers

10 Source:
Scientists estimate that millions of tons of toxic pollutants are released into the air each year. Most air toxics originate from manmade sources, including both mobile sources (e.g., cars, buses, trucks) and stationary sources (e.g., factories, refineries, power plants). However, some are released in major amounts from natural sources such as forest fires. Routine emissions from stationary sources constitute almost one-half of all manmade air toxics emissions.

11 54 million metric tons from mobile sources in 1990
There are two types of stationary sources that generate routine emissions of air toxics: "Major" sources are defined as sources that emit 10 tons per year of any of the listed toxic air pollutants, or 25 tons per year of a mixture of air toxics. Examples include chemical plants, steel mills, oil refineries, and hazardous waste incinerators. These sources may release air toxics from equipment leaks, when materials are transferred from one location to another, or during discharge through emissions stacks or vents. One key public health concern regarding major sources is the health effects on populations located downwind from them. "Area" sources consist of smaller sources, each releasing smaller amounts of toxic pollutants into the air. Area sources are defined as sources that emit less than 10 tons per year of a single air toxic, or less than 25 tons per year of a mixture of air toxics. Examples include neighborhood dry cleaners and gas stations. Though emissions from individual area sources are often relatively small, collectively their emissions can be of concern—particularly where large numbers of sources are located in heavily populated areas. EPA’s published list of "source categories" now contains 175 categories of industrial and sources that emit one or more toxic air pollutants. For each of these source categories, EPA indicated whether the sources are considered to be "major" sources or "area" sources. The 1990 Clean Air Act Amendments direct EPA to set standards requiring all major sources of air toxics (and some area sources that are of particular concern) to significantly reduce their air toxics emissions.

12 Human Impact on Atmosphere
Burning Fossil Fuels Using Nitrogen fertilizers and burning fossil fuels Refining petroleum and burning fossil fuels Manufacturing Adds CO2 and O3 to troposphere Global Warming Altering Climates Produces Acid Rain Releases NO, NO2, N2O, and NH3 into troposphere Produces acid rain Releases SO2 into troposphere Releases toxic heavy metals (Pb, Cd, and As) into troposphere air/products.html

13 Criteria Air Pollutants
EPA uses six "criteria pollutants" as indicators of air quality Nitrogen Dioxide: NO2 Ozone: ground level O3 Carbon monoxide: CO Lead: Pb Particulate Matter: PM10 (PM 2.5) Sulfur Dioxide: SO2 Volatile Organic Compounds: (VOCs) EPA established for each concentrations above which adverse effects on health may occur

14 Nitrogen Dioxide (NO2) Properties: reddish brown gas, formed as fuel burnt in car, strong oxidizing agent, forms Nitric acid in air Effects: acid rain, lung and heart problems, decreased visibility (yellow haze), suppresses plant growth Sources: fossil fuels higher temperatures, power plants, forest fires, volcanoes, bacteria in soil Class: Nitrogen oxides (NOx) EPA Standard: ppm

15 Mobile Source Emissions: Nitrogen Oxides

16 Ozone (O3) Properties: colorless, unpleasant odor, major part of photochemical smog Effects: lung irritant, damages plants, rubber, fabric, eyes, 0.1 ppm can lower PSN by 50%, Sources: Created by sunlight acting on NOx and VOC , photocopiers, cars, industry, gas vapors, chemical solvents, incomplete fuel combustion products Class: photochemical oxidants

17 Ozone (O3) 10,000 to 15,000 people in US admitted to hospitals each year due to ozone- related illness Children more susceptible Airways narrower More time spent outdoors

18 Mobile Source Emissions: Hydrocarbons – Precursors to Ozone

19 Carbon Monoxide (CO) Properties: colorless, odorless, heavier than air, % of atmosphere Effects: binds tighter to Hb than O2, mental functions and visual acuity, even at low levels Sources: incomplete combustion of fossil fuels % from auto exhaust Class: carbon oxides (CO2, CO) EPA Standard: 9 ppm 5.5 billion tons enter atmosphere/year

20 Mobile Source Emissions - CO

21 Lead (Pb) Properties: grayish metal
Effects: accumulates in tissue; affects kidneys, liver and nervous system (children most susceptible); mental retardation; possible carcinogen; 20% of inner city kids have [high] Sources: particulates, smelters, batteries Class: toxic or heavy metals EPA Standard: 1.5 ug/m3 2 million tons enter atmosphere/year

22 Suspended Particulate Matter (PM10)
Properties: particles suspended in air (<10 um) Effects: lung damage, mutagenic, carcinogenic, teratogenic Sources: burning coal or diesel, volcanoes, factories, unpaved roads, plowing, lint, pollen, spores, burning fields Class: SPM: dust, soot, asbestos, lead, PCBs, dioxins, pesticides EPA Standard: 50 ug/m3 (annual mean)

23 Mobile Source Emissions: Fine Particulate Matter (PM2.5)

24 Sulfur Dioxide (SO2) Properties: colorless gas with irritating odor
Effects: produces acid rain (H2SO4), breathing difficulties, eutrophication due to sulfate formation, lichen and moss are indicators Sources: burning high sulfur coal or oil, smelting or metals, paper manufacture Class: sulfur oxides EPA Standard: 0.3 ppm (annual mean) Combines with water and NH4 to increase soil fertility

25 VOCs (Volatile Organic Compounds)
Properties: organic compounds (hydrocarbons) that evaporate easily, usually aromatic Effects: eye and respiratory irritants; carcinogenic; liver, CNS, or kidney damage; damages plants; lowered visibility due to brown haze; global warming Sources: vehicles (largest source), evaporation of solvents or fossil fuels, aerosols, paint thinners, dry cleaning Class: HAPs (Hazardous Air Pollutants) Methane Benzene Chlorofluorocarbons (CFCs), etc. Concentrations indoors up to 1000x outdoors 600 million tons of CFCs


27 Other Air Pollutants Carbon dioxide ChloroFluoroCarbons Formaldehyde
Benzene Asbestos Manganese Dioxins Cadmium Others not yet fully characterized

28 Photochemical Smog Short Video

29 Formation & Intensity Factors
Local climate (inversions, air pressure, temperature, humidity) Topography (hills and mountains) Population density Amount of industry Fuels used by population and industry for heating, manufacturing, transportation, power Weather: rain, snow,wind Buildings (slow wind speed) Mass transit used Economics

30 Smog Forms ...when polluted air is stagnant
(weather conditions, geographic location) Los Angeles, CA

31 Primary Pollutants CO CO2 Secondary Pollutants SO2 NO NO2 SO3
Most hydrocarbons HNO3 H2SO4 Most suspended particles H2O2 O3 PANs SO4 2 Most NO3 and salts Natural Sources Stationary Mobile

32 Photochemical Smog UV radiation H2O + O2 Primary Pollutants
NO2 + Hydrocarbons Secondary Pollutants HNO3 O3 nitric acid ozone Photochemical Smog Auto Emissions


34 Air Pollution Results



37 Indoor Air Pollution

38 Why is indoor air quality important?
70 to 90% of time spent indoors, mostly at home Many significant pollution sources in the home (e.g. gas cookers, paints and glues) Personal exposure to many common pollutants is driven by indoor exposure Especially important for susceptible groups – e.g. the sick, old and very young

39 Exposure Time spent in various environments in US and less-developed countries

40 House of Commons Select Committee Enquiry on Indoor Air Pollution (1991)
“[There is] evidence that 3 million people have asthma in the UK… and this is increasing by 5% per annum.” “Overall there appears to be a worryingly large number of health problems which could be connected with indoor pollution and which affect very large numbers of the population.” [The Committee recommends that the Government] “develop guidelines and codes of practice for indoor air quality in buildings which specifically identify exposure limits for an extended list of pollutants…”

41 Sources of Indoor Air Pollutants
Building materials Furniture Furnishings and fabrics Glues Cleaning products Other consumer products Combustion appliances (cookers and heaters) Open fires Tobacco smoking Cooking House dust mites, bacteria and moulds Outdoor air

42 Important Indoor Air pollutants
Nitrogen dioxide Carbon monoxide Formaldehyde Volatile Organic Compounds (VOCs) House dust mites (and other allergens, e.g. from pets) Environmental tobacco smoke Fine particles Chlorinated organic compounds (e.g. pesticides) Asbestos and man-made mineral fibres Radon

43 Health Effects Nitrogen dioxide Respiratory irritant
Elevated risk of respiratory illness in children, perhaps resulting from increased susceptibility to respiratory infection; inconsistent evidence for effects in adults Concentrations in kitchens can readily exceed WHO and EPA standards

44 Health Effects Carbon monoxide An asphyxiant and toxicant
Hazard of acute intoxication, mostly from malfunctioning fuel-burning appliances and inadequate or blocked flues Possibility of chronic effects of long-term exposure to non- lethal concentrations, particularly amongst susceptible groups

45 Health Effects Formaldehyde
Sensory and respiratory irritant and sensitizer Possible increased risk of asthma and chronic bronchitis in children at higher exposure levels Individual differences in sensory and other transient responses Caution over rising indoor concentrations

46 Health Effects Volatile Organic Compounds (VOCs)
Occur in complex and variable mixtures Main health effects relate to comfort and well- being, but benzene (and other VOCs) are carcinogenic Concern about possible role of VOCs in the aetiology of multiple chemical sensitivity; also implicated in sick building syndrome

47 Health Effects House dust mites
House dust mites produce Der p1 allergen, a potent sensitizer Good evidence of increased risk of sensitization with increasing allergen exposure, but this does not necessarily lead to asthma Small reductions in exposure will not necessarily lead to reduced incidence and/or symptoms Indoor humidity is important

48 Health Effects Fungi and bacteria
Dampness and mould-growth linked to self- reported respiratory conditions, but little convincing evidence for association between measured airborne fungi and respiratory disease Insufficient data to relate exposure to (non- pathogenic) bacteria to health effects in the indoor environment

49 Health Effects Environmental tobacco smoke (ETS)
Sudden infant death syndrome Lower respiratory tract illness Middle ear disease Asthma 12 million children exposed to secondhand smoke in homes

50 Health Effects Fine particles
Consistent evidence that exposure to small airborne particles (e.g. PM10) in ambient air can impact on human health; mechanisms uncertain Chronic Obstructive Pulmonary Disease and Cardiovascular Disease patients and asthmatics probably at extra risk Relative importance of indoor sources is unknown

51 Health Effects Radon Can cause lung cancer
Estimated that 7,000 to 30,000 Americans die each year from radon-induced lung cancer Only smoking causes more lung cancer deaths Smokers more at risk than non-smokers

52 Radon Risk: Non-Smoker
Radon Level (pCI/L) If 1000 people who did not smoke were exposed to this level over a lifetime.. About X would get lung cancer This risk of cancer from radon exposure compares to … What to do: 20 8 Being killed in a violent crime Fix your home 10 4 3 10x risk of dying in a plane crash 2 Risk of drowning <1 Risk of dying in a home fire 1.3 Average indoor radon level 0.4 If you are a former smoker, your risk may be higher

53 Radon Risk: Smoker If you are a former smoker, your risk may be lower
Radon Level (pCI/L) If 1000 people who smoke were exposed to this level over a lifetime.. About X would get lung cancer This risk of cancer from radon exposure compares to … What to do: Stop smoking and … 20 135 100x risk of drowning Fix your home 10 71 100x risk of dying in a home fire 8 57 4 29 100x risk of dying in a plane crash 2 15 2x the risk of dying in a car crash 1.3 9 Average indoor radon level 0.4 3 If you are a former smoker, your risk may be lower

54 Radon 55% of our exposure to radiation comes from radon
colorless, tasteless, odorless gas formed from the decay of uranium found in nearly all soils levels vary

55 (From:
Zone pCi/L >4 <2

56 Radon: How it Enters Buildings
Cracks in solid floors Construction joints Cracks in walls Gaps in suspended floors Gaps around service pipes Cavities inside walls The water supply

57 Radon: Reducing the Risks
Sealing cracks in floors and walls Simple systems using pipes and fans More information: ch Such systems are called "sub-slab depressurization," and do not require major changes to your home. These systems remove radon gas from below the concrete floor and the foundation before it can enter the home. Similar systems can also be installed in houses with crawl spaces.

58 Sick Building Syndrome (SBS) vs Building Related Illness (BRI)

59 Sick Building Syndrome
A persistent set of symptoms in > 20% population Causes(s) not known or recognizable Complaints/Symptoms relieved after exiting building

60 Complaints/Symptoms Headaches Dry Skin Fatigue Nasal Congestion
Reduced Mentation Irritability Eye, nose or throat irritation Dry Skin Nasal Congestion Difficulty Breathing Nose Bleeds Nausea

61 Building Related Illness
Clinically Recognized Disease Exposure to indoor air pollutants Recognizable Causes

62 Clinically Recognized Diseases
Pontiac Fever – Legionella spp. Legionnaire's Disease Hypersensitivity Pneumonitis Humidifier Fever Asthma Allergy Respiratory Disease Chronic Obstructive Pulmonary Disease

63 Ventilation

64 Movement of Air Into / Out of Homes
Amount of air available to dilute pollutants important indicator of the likely contaminant concentration Indoor air can mix with outside air by three mechanisms infiltration natural ventilation forced ventilation

65 Movement of Air Into / Out of Homes
Infiltration natural air exchange that occurs between a building and its environment when the doors and windows are closed leakage through holes or openings in the building envelope pressure induced due to pressure differentials inside and outside of the building especially important with cracks and other openings in wall


67 Movement of Air Into / Out of Homes
Natural ventilation air exchange that occurs when windows or doors are opened to increase air circulation Forced ventilation mechanical air handling systems used to induce air exchange using fans and blowers Trade-offs cut infiltration to decrease heating and cooling costs vs. indoor air quality problems

68 Movement of Air Into / Out of Homes
Infiltration rates Influenced by how fast wind is blowing, pressure differentials temperature differential between inside and outside of house location of leaks in building envelope

69 Air Pollution Prevention

70 Specific Air Pollution Treatment Technology
Traditional Move factory to remote location Build taller smokestack so wind blows pollution elsewhere New Biofiltration : vapors pumped through soil where microbes degrade High-energy destruction: high-voltage electricity Membrane separation: diffusion of organic vapors through membrane Oxidation: High temperature combustor

71 Absorption

72 Adsorption

73 Combustion

74 Cyclone

75 Filtration

76 Electrostatic Precipitator

77 Liquid Scrubber

78 Sulfur Dioxide Control
Advanced Flue Gas Desulfurization Demonstration Project |Objective: To reduce SO2 emissions by 95% or more at approximately one-half the cost of conventional scrubbing technology, significantly reduce space requirements, and create no new waste streams. Technology/Project Description: Pure Air built a single SO2 absorber for a 528-MWe power plant. Although the largest capacity absorber module of its time in the United States, space requirements were modest because no spare or backup absorber modules were required. The absorber performed three functions in a single vessel: prequenching, absorbing, and oxidation of sludge to gypsum. Additionally, the absorber was of a co-current design, in which the flue gas and scrubbing slurry move in the same direction and at a relatively high velocity compared to that in conventional scrubbers. These features all combined to yield a state-of-the-art SO2 absorber that was more compact and less expensive than contemporary conventional scrubbers. Other technical features included the injection of pulverized limestone directly into the absorber, a device called an air rotary sparger located within the base of the absorber, and a novel wastewater evaporation system. The air rotary sparger combined the functions of agitation and air distribution into one piece of equipment to facilitate the oxidation of calcium sulfite to gypsum. Pure Air also demonstrated a unique gypsum agglomeration process, PowerChip®, to significantly enhance handling characteristics of adsorbed flue gas desulfurization AFGD-derived gypsum.

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