Human Impact on the Human Impact on the AtmosphereAtmosphere

Chapters 16 Air Pollution

Advanced Placement Environmental Science

PollutionPollution Thorpe, Gary S., M.S., (2002). Barron’s How to prepare for the AP Environmental Science Advanced Placement ExamThorpe, 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 The term “Smog” (smoke and fog) was first used in 1905 to describe sulfur dioxide used in 1905 to describe sulfur dioxide emissionemission

• In 1952, severe pollution took the lives of In 1952, severe pollution took the lives of 5000 people in London 5000 people in London

• ““It isn’t pollution that’s harming the It isn’t pollution that’s harming the environment. It’s the impurities in our air and environment. It’s the impurities in our air and water that are doing it.” water that are doing it.” FormerFormer U.S. Vice President Dan QuayleU.S. Vice President Dan Quaylewww.aqmd.gov/pubinfo/ 97annual.html

TheTheCleaClea

nnAirAirActAct

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

Clean Air ActClean 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

Clean Air ActClean Air Act• 1990 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

Pollutants CategoriesPollutants 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.

Pollution CategoriesPollution Categories

3. 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.

Outdoor Air PollutionOutdoor Air Pollution

Major Sources of Primary Major Sources of Primary PollutantsPollutants

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

54 million metric tons from mobile sources in 1990

Human Impact on Human Impact on AtmosphereAtmosphere

• 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

www.dr4.cnrs.fr/gif-2000/ air/products.html

Criteria Air PollutantsCriteria Air PollutantsEPA uses six "criteria pollutants" as indicators of air quality

1. Nitrogen Dioxide: NO2

2. Ozone: ground level O3

3. Carbon monoxide: CO4. Lead: Pb5. Particulate Matter: PM10 (PM 2.5)

6. Sulfur Dioxide: SO2

• Volatile Organic Compounds: (VOCs)

EPA established for each concentrations above which adverse effects on health may occur

Nitrogen Dioxide (NONitrogen Dioxide (NO22))• 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 combustion @ higher temperatures, power plants, forest fires, volcanoes, bacteria in soil

• Class: Nitrogen oxides (NOx) • EPA Standard: 0.053 ppm

Mobile Source Mobile Source Emissions: Nitrogen Emissions: Nitrogen

OxidesOxides

Ozone (OOzone (O33))• 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

Ozone (OOzone (O33))• 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

Mobile Source Mobile Source Emissions: Emissions:

Hydrocarbons – Hydrocarbons – Precursors to OzonePrecursors to Ozone

Carbon Monoxide (CO)Carbon Monoxide (CO)• Properties: colorless, odorless, heavier

than air, 0.0036% of atmosphere• Effects: binds tighter to Hb than O2,

mental functions and visual acuity, even at low levels

• Sources: incomplete combustion of fossil fuels 60 - 95% from auto exhaust

• Class: carbon oxides (CO2, CO)

• EPA Standard: 9 ppm • 5.5 billion tons enter atmosphere/year

Mobile Source Mobile Source Emissions - COEmissions - CO

Lead (Pb)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

Suspended Particulate Matter (PMSuspended Particulate Matter (PM1010)) •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)

Mobile Source Emissions: Mobile Source Emissions: Fine Particulate Matter Fine Particulate Matter

(PM(PM2.52.5))

Sulfur Dioxide (SOSulfur Dioxide (SO22)) • 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

VOCs (Volatile Organic Compounds)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

Other Air PollutantsOther Air Pollutants• Carbon dioxideCarbon dioxide• CChlorohloroFFluoroluoroCCarbonsarbons• FormaldehydeFormaldehyde• BenzeneBenzene• AsbestosAsbestos• ManganeseManganese• DioxinsDioxins• CadmiumCadmium• Others not yet fully characterizedOthers not yet fully characterized

Photochemical SmogPhotochemical Smog

• Short Video

Formation & IntensityFormation & IntensityFactorsFactors• Local climate (inversions, air pressure, Local climate (inversions, air pressure,

temperature, humidity)temperature, humidity)• Topography (hills and mountains)Topography (hills and mountains)• Population densityPopulation density• Amount of industryAmount of industry• Fuels used by population and industry for Fuels used by population and industry for

heating, manufacturing, transportation, powerheating, manufacturing, transportation, power• Weather: rain, snow,windWeather: rain, snow,wind• Buildings (slow wind speed)Buildings (slow wind speed)• Mass transit usedMass transit used• Economics Economics

...when polluted air is stagnant (weather conditions, geographic location)

Los Angeles, CA

Smog FormsSmog Forms

Primary PollutantsPrimary Pollutants

Secondary PollutantsSecondary Pollutants

SourcesSourcesNaturalNaturalStationaryStationary

COCO COCO22

SOSO22 NONO NONO22

Most hydrocarbonsMost hydrocarbons

Most suspendedMost suspendedparticlesparticles

SOSO33

HNOHNO33 HH22SOSO44

HH22OO22 OO33 PANsPANs

MostMost andand saltssaltsNONO33––

MobileMobile

SOSO4422 ––

Photochemical SmogPhotochemical Smog

Primary Pollutants

NO2 + Hydrocarbons

Auto Emissions

UV radiation

H2O + O2

Secondary Pollutants

HNO3 O3

nitric acid ozone

Photochemical Smog

Air Pollution ResultsAir Pollution Results

Indoor Air PollutionIndoor Air Pollution

Why is indoor air quality Why is indoor air quality important?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

ExposureExposure• Time spent in various environments

in US and less-developed countries

House of Commons Select House of Commons Select Committee Enquiry on Indoor Air Committee Enquiry on Indoor Air

Pollution (1991)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…”

Sources of Indoor Air Sources of Indoor Air PollutantsPollutants

• 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

Important Indoor Air Important Indoor Air pollutantspollutants

• 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

Health EffectsHealth EffectsNitrogen 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

Health EffectsHealth 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

Health EffectsHealth EffectsFormaldehyde• 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

Health EffectsHealth EffectsVolatile 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

Health EffectsHealth EffectsHouse 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

Health EffectsHealth EffectsFungi 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

Health EffectsHealth EffectsEnvironmental tobacco smoke (ETS)• Sudden infant death syndrome

• Lower respiratory tract illness

• Middle ear disease • Asthma

12 million children exposed to secondhand 12 million children exposed to secondhand smoke in homessmoke in homes

Health EffectsHealth EffectsFine 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

Health EffectsHealth 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

Radon Risk: Non-SmokerRadon Risk: Non-SmokerRadon 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 Fix your home

8 3 10x risk of dying in a plane crash

Fix your home

4 2 Risk of drowning Fix your home

2 <1 Risk of dying in a home fire

Fix your home

1.3 <1 Average indoor radon level Fix your home

0.4 <1 Average indoor radon level Fix your home

If you are a former smoker, your risk may be higherIf you are a former smoker, your risk may be higher

Radon Risk: SmokerRadon Risk: SmokerRadon 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

Fix your home

8 57 Fix your home

4 29 100x risk of dying in a plane crash

Fix your home

2 15 2x the risk of dying in a car crash

Fix your home

1.3 9 Average indoor radon level Fix your home

0.4 3 Average indoor radon level Fix your home

If you are a former smoker, your risk may be lowerIf you are a former smoker, your risk may be lower

RadonRadon

• 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

(From: http://www.epa.gov/iaq/radon/zonemap.html)

Zone pCi/L 1 >4 2 2 - 4 3 <2

Radon: How it Enters Radon: How it Enters BuildingsBuildings

• Cracks in solid floors• Construction joints• Cracks in walls• Gaps in suspended

floors• Gaps around service

pipes• Cavities inside walls• The water supply

http://www.epa.gov/iaq/radon/pubs/citguide.html#howdoes

Radon: Reducing the Radon: Reducing the RisksRisks• Sealing cracks in floors and walls

• Simple systems using pipes and fans

• More information:

http://www.epa.gov/iaq/radon/pubs/consguid.html#reductiontech

Sick Building Syndrome (SBS)Sick Building Syndrome (SBS)

vsvs

Building Related Illness (BRI)Building Related Illness (BRI)

Sick Building SyndromeSick Building Syndrome

• A persistent set of symptoms in > 20% population

• Causes(s) not known or recognizable• Complaints/Symptoms relieved after exiting

building

Complaints/SymptomsComplaints/Symptoms

• Headaches

• Fatigue

• Reduced Mentation

• Irritability

• Eye, nose or throat irritation

• Dry Skin• Nasal Congestion• Difficulty Breathing• Nose Bleeds• Nausea

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

Clinically Recognized Clinically Recognized DiseasesDiseases

–Pontiac Fever – Legionella spp.–Legionnaire's Disease–Hypersensitivity Pneumonitis–Humidifier Fever–Asthma–Allergy–Respiratory Disease

• Chronic Obstructive Pulmonary Disease

VentilationVentilation

Movement of Air Into / Out of Movement of Air Into / Out of HomesHomes

• 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

Movement of Air Into / Out of Movement of Air Into / Out of HomesHomes• 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

Movement of Air Into / Out of Movement of Air Into / Out of HomesHomes• 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

Movement of Air Into / Out of Movement of Air Into / Out of HomesHomes

• 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

Air Pollution Air Pollution PreventionPrevention

Specific Air Pollution Treatment Specific Air Pollution Treatment TechnologyTechnology

• 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

AbsorptionAbsorption

AdsorptionAdsorption

CombustionCombustion

CycloneCyclone

FiltrationFiltration

Electrostatic PrecipitatorElectrostatic Precipitator

Liquid ScrubberLiquid Scrubber

Sulfur Dioxide Sulfur Dioxide ControlControl

http://www.apt.lanl.gov/projects/cctc/factsheets/puair/adflugasdemo.html