Dr. Largen

• Air Pollution
• Indoor Air Pollution
• Acid Deposition
• Greenhouse Gases & Global Warming

• Air quality
• degraded by
• natural events
• volcanic gases & particulates
• dust
• gases from decomposition of organic material
• activities of humans
• automobile emissions
• industrial process emissions
• air pollution
• degradation caused by human activities
• related to
• number of people
• kinds of activities
• material into the air is not disposed of
• it is diluted, moved around
• air pollution results in
• reduced aesthetic value of scenery
• human health problems
• damage to ecosystems
• international conflicts
• damage to structures
• increased costs
• air pollution
• incidents
• Donora, PA in 1948
• pollutants from zinc plant and steel mills became trapped in valley
• temperature inversion
• formed dense fog
• within five days
• 17 people died
• 5,910 people became ill
• 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 pollution
• air pollutants in US
• accumulate due to predominant west to east winds
• as air mass moves from west to east
• each population center adds pollutants to total load
• Primary air pollutants
• 5 major types of materials
• primary air pollutants
• carbon monoxide
• volatile organic compounds (VOC) (hydrocarbons)
• particulate matter
• sulfur dioxide
• nitrogen oxides
• Primary air pollutants
• interact with one another in presence of sunlight to form
• secondary air pollutants
• ozone
• other PANs (peroxyacyl nitrates)
• Primary air pollutants
• 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
• ­ # automobiles
• ­ # km driven
• 2nd largest source is tobacco smoke
• not a persistent pollutant
• natural processes convert it to non-harmful compounds
• combines with O in air to form CO₂
• air can be cleared if no other new CO is introduced

• toxic to humans and other animals
• strongly attracted to hemoglobin in blood
• takes up CO nearly 250 times more rapidly than O₂
• death can result from several hours of exposure to air containing only 0.001% of CO
• from 1970-2000
• CO levels decreased ~25%
• volatile organic compounds (VOCs)
• primarily composed of C and H
• also referred to as hydrocarbons
• produced by
• evaporation from fuel supplies
• incomplete combustion of fuels
• contribute to formation of secondary air pollutants in smog
• sources of emissions
• major
• internal combustion engine
• additional
• oil refineries and other industries
• oil based paint
• charcoal lighter fluid
• modifications to automobile engines help reduce emissions
• recycling some gases through engines
• using higher O concentrations in fuel-air mixture
• using valves to prevent escape of gases
• catalytic converters burn exhaust gases more completely
• from 1970-2000
• VOC quantities decreased ~43%
• Particulate matter
• minute solid particles and liquid droplets dispersed into atmosphere
• grouped by particle size
• <10 microns (PM₁₀)
• <2.5 microns (PM_2.5)
• <10 microns (PM₁₀)
• sources
• travel on roads
• agricultural activities
• construction
• industrial processes
• smoke from fires
• desertification
• volcanoes
• <2.5 microns (PM_2.5) sources
• mostly secondary pollutants that form in atmosphere from interactions of primary pollutants
• produce variety of problems
• "visual" pollution
• smoke
• obstructed views
• soot settling on surfaces
• caused by smoke
• produce variety of problems
• health
• accumulate in lungs and interfere with ability to exchange gases
• serve as deposition centers for other harmful substances
• from 1970-2000
• <10 microns (PM₁₀)
• decreased ~88%
• from 1991-2000
• <2.5 microns (PM_2.5)
• decreased ~6%
• Sulfur dioxide (SO₂)
• produced
• combustion of sulfur-containing fossil fuels
• react with water, other materials to form sulfur-containing acids
• involved in acid deposition
• affect health
• acids become attached to particles that are inhaled
• very corrosive to lung tissue
• Sulfur dioxide (SO₂), some incidents
• in 1306, Edward I of England, in London
• banned burning of "sea coles"
• coals from seashore high in sulfur content
• responsible for London’s poor air quality
• may be earliest environmental legislation concerning air quality
• in 1952, London killer fog
• covered for several days by dense "killer" fog
• air didn’t mix because of temperature conditions
• factories continued releasing smoke & dust
• producing "smog" (mixture of smoke and fog)
• within few weeks 4,000 people died
• deaths attributed to high level of sulfur compounds in smog
• 1000’s of others suffered from
• severe bronchial irritation, sore throats, chest pains
• Sulfur dioxide (SO₂)
• from 1970-2000
• levels have decreased ~44%

• Nitrogen oxides (NO_x)
• produced
• when N & O in air react under high temperatures associated with combustion
• most common are
• nitrogen oxide (NO)
• nitrogen dioxide (NO₂)
• really a secondary pollutant because it forms from interaction of NO with oxygen
• mixture of NO and NO₂ is called NO_x
• noteworthy because of role they play in production of
• secondary air pollutants (photochemical smog)
• primary source
• automobile engine
• catalytic converters help reduce amount released
• ~ 75% of NO is converted back to nitrogen gas and oxygen gas
• from 1971-2000
• NO_x levels increased ~20%
• due to increased automobile traffic

• Secondary air pollutants
• compounds that result from interaction of various primary air pollutants
• photochemical smog
• 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)
• photochemical smog
• ozone & peroxyacyl nitrates (PANs)
• 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
• Typical photochemical smog event
• morning traffic produces lots of NO
• N₂ + O_{2 ®} 2NO
• NO reacts with molecular O₂ from atmosphere to form NO₂, gives photochemical smog its reddish-brown haze
• 2NO + O_{2 ®} 2NO₂
• later in morning, NO₂ reacts with UV in sunlight to form atomic O
• NO_{2 ®} UV light ® NO + O
• molecular O₂ in atmosphere reacts with atomic O to form ozone
• O₂ + O _® O₃
• problem varies by region due to
• climate, geography, population and activities
• Los Angeles, Salt Lake City, Phoenix
• ringed by mountains
• prevailing winds 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

• Indoor air pollution
• scientific evidence indicates indoor air is more seriously polluted than outdoor air
• indoor air pollutants
• asbestos
• formaldehyde
• wood products, aerosols
• pesticide residues
• chloroform
• perchloroethylene
• dry cleaning
• paradichlorobenzene
• mothballs, air fresheners
• organisms
• disease-causing
• allergy-producing
• lead
• carbon monoxide
• radon
• source is uranium-238
• inert radioactive gas, half-life of 3.8 days
• associated with increased risk of lung cancer
• ~15,000 deaths annually attributed to radon
• forms in rocks, diffuses upwards into soil, water, atmosphere
• can enter homes through foundation
• ~10% of US homes have potential radon problem
• homes with levels >4 picocuries/liter should implement corrective actions
• risk varies by area of country
• tobacco smoke
• most important air pollutant in US in terms of human health
• estimated 350,000 die in US annually from tobacco smoke
• emphysema, heart attacks, strokes, lung cancer, other related diseases
• banning smoking would probably save more lives than any other pollution-control measure
• Indoor air pollution
• contributing factors
• people spend on average 70-90% of our time indoors
• energy-efficient buildings
• trap air pollutants
• complete air exchange every 5 hours
• older hours complete exchange occurred every hour

Air Quality Issues: Indoor Air Pollution

• Indoor air pollution
• in 1990
• EPA placed indoor air pollution at top of list of 18 sources of cancer risk
• sick buildings
• EPA states at least 1/5 of all buildings in US are "sick"