Air PollutionChapter 18Chapter 18

South Asia’s South Asia’s Massive Brown CloudMassive Brown Cloud

Asian Brown Cloud-2 miles thickAsian Brown Cloud-2 miles thick CausesCauses Chemical composition- Chemical composition- dust, smoke, ash, dust, smoke, ash,

Areas impacted (India, Bangladesh, and China)Areas impacted (India, Bangladesh, and China) Reduced photosynthesis by about 7%Reduced photosynthesis by about 7% Air pollution connects the world –LAAir pollution connects the world –LA 2 weeks to circle the globe2 weeks to circle the globe Steps taken in China and India to reduce air Steps taken in China and India to reduce air

pollutionpollution coal to natural gas coal to natural gas

Air Pollution in Shanghai, Air Pollution in Shanghai, China, China,

• Intro video• The Asian Brown Cloud

18.1 The Atmosphere 18.1 The Atmosphere Consists of Consists of

Several LayersSeveral Layers Divided into layers based on temperature

changes from differences in absorption of incoming solar energy

Atmosphere varies in Density-higher at sea level than top of mountain Atmospheric pressure -decreases with altitude –

less gas molecules at higher altitudes Influenced by Gravity-pulls gas molecules

towards Earth’s surface

Air Movements in the Troposphere Play a Key Air Movements in the Troposphere Play a Key Role in Earth’s Weather and ClimateRole in Earth’s Weather and Climate

Troposphere Troposphere 75–80% of the earth’s air mass Closest to the earth's surface 0-11 km above sea level Chemical composition of air

Nitrogen 78% Oxygen 21% H20, CO2, trace amounts of others (Ar)

Weather, climate and all life forms exist here Involved in chemical cycling Upper boundary = tropopause As altitude increases, temperature decreases

The Stratosphere Is Our Global The Stratosphere Is Our Global SunscreenSunscreen

StratosphereStratosphere 11-50 km above Earth's surface

Similar composition to the troposphere, with 2 exceptions

Much less water (1/1000) O3, ozone layer

As altitude increases, temperature increases

Air motion is horizontal Airplanes fly here

OZONE OOZONE O3 3 – our global – our global sunscreensunscreen

Keeps 95 + % of UV rays from Earth's surface

Allows humans and other life to exist on Allows humans and other life to exist on earthearth

Helps protect humans from sunburn, Helps protect humans from sunburn, cancer, cataracts and damage to the cancer, cataracts and damage to the immune systemimmune system

MesosphereMesosphere 50-80 km

As altitude increases, temperature decreases

Very little O3

Middle atmosphere – Air thin, pressure low

Need oxygen to live in this region. Air quite cold -90°C (-130°F) near the top of mesosphere

ThermosphereThermosphere Altitude increases, temperature

increases “Hot layer” – oxygen molecules

absorb energy from solar rays warming the air. Very few atoms and molecules in this region.

Intense UV – breaks O2 and N2 bonds

International Space Station is here

Comparison of the lower Comparison of the lower atmosphere with the higher atmosphere with the higher

atmosphereatmosphere Continuous mixingContinuous mixing Constant, uniform Constant, uniform

chemical chemical compositioncomposition

Fairly constant Fairly constant temp over a 24 temp over a 24 hour periodhour period

Still air – slow Still air – slow diffusion of gasesdiffusion of gases

Different Different composition at composition at different heightsdifferent heights

Wide temperature Wide temperature variationsvariations

The Earth’s Atmosphere Is a The Earth’s Atmosphere Is a Dynamic System with Four Dynamic System with Four

LayersLayers

18.2 What are the major 18.2 What are the major outdoor air pollution outdoor air pollution

problems?problems?

Air Pollution Comes from Air Pollution Comes from Natural SourcesNatural Sources

Air pollution: presence of chemicals in atmosphere in concentrations high enough to harm organisms

Natural sources Dust blown by wind Pollutants from wildfires and volcanoes Volatile organics released by plants – mold

and terpenes

Air Pollution Comes from Air Pollution Comes from Human Sources (anthropogenic)Human Sources (anthropogenic)

Human sources: mostly in industrialized and/or urban areas Stationary sources - power and

industrial plants Mobile sources - cars, buses

Air Pollution in the Past: Air Pollution in the Past: The Bad Old DaysThe Bad Old Days

Discovery of fire-may have started air pollution problem

Middle Ages-haze of wood smoke over densely populated urban areas

Industrial Revolution-late 1700’s coal being burned for factories and homes-increase in respiratory diseases

London, England 1850s 1952: yellow fog-lasted 5 days-killed over 4,000 Clean Air Act of 1956

The London Smog of 1952The London Smog of 1952 London naturally has very calm air, London naturally has very calm air,

and regularly experiences thick sea and regularly experiences thick sea fog.fog.

The weather turned unusually cold, The weather turned unusually cold, causing the residents to burn greater causing the residents to burn greater amounts of coal to heat their homes.amounts of coal to heat their homes.

This combined with a temperature This combined with a temperature inversion to create a thick smog of inversion to create a thick smog of sulfur dioxide over the city.sulfur dioxide over the city.

The number of fatalities is unknown, The number of fatalities is unknown, but estimated to be 4,000- 12,000.but estimated to be 4,000- 12,000.

1616

United States 1948: Donora, PA; first U.S. air

pollution disaster-coal burning factories, steel mills, zinc smelter and sulfuric acid trapped in fog

1963: New York City - killed 300 Global problem

Air Pollution HistoryAir Pollution History The Donora Fluoride Fog of 1948The Donora Fluoride Fog of 1948

In late October, the town of Donora In late October, the town of Donora experienced a temperature inversion.experienced a temperature inversion.

The town is located along the The town is located along the Monongahela River south of Pittsburgh, Monongahela River south of Pittsburgh, within a small valley.within a small valley.

The main employer of the town was a US The main employer of the town was a US Steel Zinc smelting plant.Steel Zinc smelting plant.

1818

Donora Fluoride FogDonora Fluoride Fog Emissions of sulfur dioxide, nitrogen Emissions of sulfur dioxide, nitrogen

dioxide, and fluoride from the zinc dioxide, and fluoride from the zinc smelting plant began to accumulate.smelting plant began to accumulate.

The smog became so thick that driving The smog became so thick that driving was impossible.was impossible.

The plant itself did not cease operations The plant itself did not cease operations until 4 days later. until 4 days later.

The smog finally broke up as a The smog finally broke up as a rainstorm entered the area after 5 days.rainstorm entered the area after 5 days.

1919

Donora Fluoride FogDonora Fluoride Fog A total of 20 residents died; About a A total of 20 residents died; About a

third to a half of the town’s entire third to a half of the town’s entire population of 14,000 became population of 14,000 became sickened.sickened.

Donora experienced higher than Donora experienced higher than normal mortality rates for 10 years normal mortality rates for 10 years afterwards.afterwards.

2020

Noon in Donora

Some Pollutants in the Atmosphere Some Pollutants in the Atmosphere Combine to Form Other PollutantsCombine to Form Other Pollutants

Primary pollutants- chemical emitted directly into air

Secondary pollutants- when primary pollutants react with each other to form new harmful chemicals – ozone, PANs, HNO3

Air quality improving in developed countries Much more needs to be done in developing countries

Indoor pollution: big threat to the poor 1 in 6 live in area where air is bad

Sources and Types of Air Pollutants

polyacrylonitrile (PAN)

What Are the Major What Are the Major Outdoor Air Pollutants?Outdoor Air Pollutants?

Carbon oxides Carbon monoxide (CO) – colorless,

odorless, highly toxic-car exhaust, open fires, tobacco smoke

Reduces ability of blood to transport oxygen to body

Carbon dioxide (CO2) colorless, odorless

Sources 93% from carbon cycle, rest from burning fossil fuels, clearing forests/grasslands

Human health and environmental impact-Global Warming

What Are the Major Outdoor Air What Are the Major Outdoor Air

PollutantsPollutants?? Nitrogen oxides (NO, NO2 and N2O) and nitric acid

(HNO3) Sources-car engines and coal burning plants Acid deposition-reacting with water vapor Photochemical smog-sun and traffic Human health and environmental impact

Sulfur dioxide (SO2) and sulfuric acid (H2SO4) Colorless, bad smell Sources – 1/3 from sulfur cycle, 2/3 humans-coal in electrical

plants and industrial plants Human health and environmental impact-Asian Brown cloud

Particulates Suspended particulate matter (SPM)

Fine Ultrafine

Sources-dust, wild fires, sea salt (~62%)cars, tobacco smoke, coal burning (~38%)

Human health and environmental impact Toxic particulates (Pb, PCBs and Cd) can cause Toxic particulates (Pb, PCBs and Cd) can cause

reproductive problems, cancer, reduce visibility and corrode reproductive problems, cancer, reduce visibility and corrode metalsmetals

60,000-70,000 premature deaths/year60,000-70,000 premature deaths/year

What Are the Major Outdoor Air What Are the Major Outdoor Air

PollutantsPollutants??

Small particles less than 10 micrometers in diameter pose the greatest problems, because they can get deep into the lungs, and some may even get into your bloodstreamFine particles (PM2.5) are the main cause of reduced visibility (haze) in parts of the United States, including many of our treasured national parks and wilderness areas.

Ozone (O3) – a secondary pollutant An unstable molecule that readily reacts to shed a single O2 atom Human and environmental impact

Volatile organic compounds (VOCs) Organic compounds that exist as gas in atmosphere

Hydrocarbons such as terpenes (C10H15 emitted by leaves of plants) and methane (CH4)

Sources-mainly plants, wetlands and termites (natural) and human sources like oil wells, landfills, cows

Other VOCs are benzene and vinyl chloride that are used as industrial solvents

Human and environmental impact Leukemia, blood disorders, immune system damage

What Are the Major Outdoor Air PollutantsWhat Are the Major Outdoor Air Pollutants??

Chemical Reactions That Form Major Outdoor Air Pollutants

Detecting Air PollutantsDetecting Air Pollutants Chemical instrumentsChemical instruments

Unmanned aircraftUnmanned aircraft Satellites-Asian Brown CloudSatellites-Asian Brown Cloud

2 miles thick, 1-3 miles above ground, covers much of 2 miles thick, 1-3 miles above ground, covers much of India, Bangladesh and China- satellites tracked its India, Bangladesh and China- satellites tracked its movement- even across the Pacific Ocean to California!movement- even across the Pacific Ocean to California!

Nanotechnology-nanodetectors?Nanotechnology-nanodetectors? Biological indicatorsBiological indicators

Lichens-fungus and algaeLichens-fungus and algae - are always absorbing air as a source of - are always absorbing air as a source of

nourishmentnourishment

Natural Capital: Lichen Species, Vulnerability to Air Pollutants

Old mans beard sickens in the presence of SO2

YellowEvernia

also sickens in SO2

Lichen are sensitive to pollution because they lack root and act like sponges, taking in and retaining everything that is in the air and dissolved in rainwater. As pollutants reach a high level, the chlorophyll in the algal portions breaks down and photosynthesis stops

Lead Is a Highly Toxic Pollutant Does not break down in the environment

Sources-toys, paint, water pipes, red, long-lasting lipsticks

Human health and environmental impact Most vulnerableMost vulnerable – children under 6 and fetuses– children under 6 and fetuses Neurotoxin-about 200 kids die per yearNeurotoxin-about 200 kids die per year

Reduction of lead (Pb) Unleaded gasoline Unleaded paint

Still problems 2007: toys with Pb paint recalled Older buildings- Pb- based paint peeling,

Pb contaminated dust, water pipes/faucets

Global bans on lead in gasoline and paint would be helpful- China just phased on leaded gasoline 5 years ao.

Lead Is a Highly Toxic Pollutant

Burning Coal Produces Industrial Burning Coal Produces Industrial Smog Smog

(gray-air smog)(gray-air smog) Chemical composition = Chemical composition = sulfur dioxide, sulfur dioxide,

suspended droplets of sulfuric acid suspended droplets of sulfuric acid (mostly from coal burning), (mostly from coal burning), suspended solid particles and suspended solid particles and dropletsdroplets

Carbon from coal and oil converted to Carbon from coal and oil converted to CO and COCO and CO22

Unburned carbon ends up as Unburned carbon ends up as particulate matter in air (soot)particulate matter in air (soot)

Reduction of this smog in urban Reduction of this smog in urban cities of the United States cities of the United States

China and SmogChina and Smog Each year 358,000 Chinese die from

air pollution (some estimate as many as 750,000 including indoor air pollution)

Relies heavily on coal burning 16 of world’s 20 most polluted

cities are in China 62% of the cities suffer from

industrial smog

How Pollutants Are Formed from Burning Coal and Oil, Leading to

Industrial Smog

Sunlight Plus Cars Equal Sunlight Plus Cars Equal Photochemical Smog – Photochemical Smog – brown air smogbrown air smog

Requires sunlight and carsRequires sunlight and cars Morning traffic releases NOx and VOCs in the airMorning traffic releases NOx and VOCs in the air UV radiation produces a series of reactions that UV radiation produces a series of reactions that

form as many as 100 different compounds such form as many as 100 different compounds such as peroxyacyl nitrates (PANs) and aldehydes.as peroxyacyl nitrates (PANs) and aldehydes.

Ozone is the most Ozone is the most abundant. abundant. In sunlight, NO2

dissociates into O and NO. The O reacts with O2 to produce ozone

Levels off pollutants peak around noon and drop Levels off pollutants peak around noon and drop during the late afternoon, then starts again the during the late afternoon, then starts again the next morning. But NO drops as the sun gets next morning. But NO drops as the sun gets higher as secondary pollutants form.higher as secondary pollutants form.

PANsPANs Peroxyacetyl nitrate causes eye irritations at very low

concentrations of only a few parts per billion. It also irritates the respiratory system. It It may cause emphysema, impaired breathing, acute pulmonary edema or lung lesions following inhalation exposure. People with heart and lung disease, children and the elderly are the most susceptible to air pollutants, including PAN.

PAN inhibits the primary process of photosynthesis in various types of plants, which can stop or reduce their growth. Pan is more toxic to plants than ozone. Affected plants exhibit discolored leaves and leaves can fall off, which further reduces photosynthesis. The plant's ability to store food, grow and reproduce is reduced, and the plants also become more vulnerable to attacks by pests and diseases.

Present in most cities – irritates eyes and respiratory tracts. The heat island effect makes the reactions worse.