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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
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
• 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
• 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
Out Door AirPollution
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
Human Impact on Air Pollution
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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
Criteria for Air Pollution
EPA uses six "criteria pollutants" as indicators of air quality
1. Nitrogen Dioxide: NO2
2. Ozone: ground level O3
3. Carbon monoxide: CO
4. Lead: Pb
5. Particulate Matter: PM10 (PM 2.5)
6. Sulfur Dioxide: SO2
7. Volatile Organic Compounds: (VOCs)
EPA established for each concentrations above which adverse effects on health may occur
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 combustion @ higher temperatures, power plants, forest fires, volcanoes, bacteria in
soil
• Class: Nitrogen oxides (NOx)
• EPA Standard: 0.053 ppm
Ozone
• 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
Carbon Monooxide (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
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 (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)
Sulfur Dioxide
• 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
VOC’s
• 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
Other Air Pollutants
• Carbon dioxide
• ChloroFluoroCarbons
• Formaldehyde
• Benzene
• Asbestos
• Manganese
• Dioxins
• Cadmium
• Others not yet fully characterized
Formation And 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
Sources of indoor Air Pollution
• 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 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
Nitrogen dioxide Health Effects
• 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
Carbon monoxide Health Effects
• 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
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
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
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Concern about possible role of VOCs in the aetiology of multiple chemical sensitivity; also implicated in
sick building syndrome
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
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
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
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
Sick Building Syndrome
Symptoms of SBS
• Headaches
• Fatigue
• Reduced Mentation
• Irritability
• Eye, nose or throat irritation
• Dry Skin
• Nasal Congestion
• Difficulty Breathing
• Nose Bleeds
• Nausea
Diseases of SBS
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Pontiac Fever – Legionella spp.
Legionnaire's Disease
Hypersensitivity Pneumonitis
Humidifier Fever
Asthma
Allergy
Respiratory Disease
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Chronic Obstructive Pulmonary Disease
Ventilation
• 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
• 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
• 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