Air (resources and pollution)

Amount of air pollutants released annually by human activity

6 billion metric tons

Learned in past decades of EPA regulations

air quality can be improved and economic growth can continue

Nonpoint-source emissions

pollution that leaks out from loose joints, fittings, holes in pipes directly into the air; don’t vent from a single location like a smokestack

Defining difference between primary and secondary pollutants

when they’re harmful

Particulates

suspended materials in the atmosphere including dust, spores, ash

PM2.5

particulate matter greater than 2.5 micrometers in side

PM2.5 and health

poses greatest health risks, lodges in lungs and can’t be removed, absorbed by bloodstream and can lead to inflammation and blockages, heavy metals and o-compounds

Anthropogenic PM2.5

mostly anthropogenic through energy production (fossil fuels, biofuel combustion) and biomass burning (clear fields for agriculture)

Anthropogenic

something created, caused, influenced by human activity

Three main air pollutants released by humans

carbon dioxide, methane, carbon monoxide

Point source emissions

come from a single source… ex is a smokestack

Primary pollutants

released directly from the source into the air in a harmful form

Secondary pollutants

converted to a hazardous form after entering the air following exposure to other chemicals and sunlight

Aerosols

very fine solid or liquid particles suspended in the atmosphere; natural or synthetic

Types of aerosols

volcanic, desert dust, anthropogenic

Important air pollutant pathways

inhaled or absorbed through the skin

Inversions are created when…

rapid nighttime cooling in a valley occurs

Impact of inversions

mixing prevented, pollutants (ie ozone) are trapped close to the ground

Chemicals in LA haze

ozone and nitrogen dioxide

Why air pollutants are concentrated at high latitudes

atmospheric circulation pushes pollutants toward the poles

Urban heat island

high temps in cities than country; low albedo of concrete & bricks contribute

Sunlight’s role

Driver of atmospheric circulation

Sunlight reflection

reflected off clouds, particles, lands, oceans (esp lots of ice/snow)

Sunlight absorption

energy from sun provides energy for molecules of atmosphere causing them to move, clouds absorb energy and dissipate

Infrared energy and sunlight

sunlight absorbed by land radiates from Earth to atmosphere

Solar energy absorbed

hot air rises

Air cools moving away from equator

cool air descends

Tubular flow cells

latitude bands around the earth

Hadley cells

tubular flow cells near equator

Ferrel cells

tubular flow cells more near to the poles

Westerlies

winds coming from the west and pushing east

Easterlies

winds coming from east and pushing west

Coriolis effect

because the earth rotates; as earth rotates eastward; Faster velocity near equator bc it needs to travel more distance than near pole

Air flows towards poles (northern hemisphere)

moving faster than ground, deflects right

Air flows away from poles (northern hemisphere)

moves slower than ground, deflects right

Air flows towards poles (southern hemisphere)

moving faster than ground, deflects left

Air flows away from poles (southern hemisphere)

moves slower than ground, deflects left

Precipitation trends

more precipitation where air rises and cools → occurs at equator; dry where air descends → around 30o N and S

Dominant components of atmosphere

nitrogen (78%) and oxygen (21%)

Atmosphere division

based on temperature vs altitude

Four main layers of atmosphere

troposphere, stratosphere, mesosphere, thermosphere

Troposphere

the air we breathe; 5-10 miles up; thinner over poles, thicker over equator

Stratosphere

higher elevations (where planes fly); top of troposphere to 30 miles high

Pollutant

substance that occurs at high enough concentrations to disrupt natural systems or affect organism health

Pollution in megacities

no/minimal pollution controls in megacities; 16/20 smoggiest cities are in China; Delhi, India named as most polluted country

Urban temperature inversions

urban pollution most extreme when inversions develop; keeps pollutants concentrated near ground (pollution capped by cool air)

Temperature inversion

stable, cold air near the ground (esp valleys), warm layers above, capped by cooler layers, opposite of normal conditions

Smog

a mixture of air pollutants general accumulated from fossil fuel combustion

Haze

generally fine particles (contributes to haze blobs)

Physical processes in the atmosphere

transport, concentrate, disperse air pollutants (go far)

Major US Clean Air Laws

1963 Clean Air Act and 1970 Amendments to Clean Air Act

1963 Clean Air Act

authorized research into monitoring and controlling air pollution

1970 Amendments to Clean Air Act

first rly strong components (EPA can establish national ambient air quality standards, state implementation plans, new course performance standards, national emissions standards for hazardous air pollutants) for stationary and mobile sources

US Clean Air Act

amended in 1970; addressed 6 major pollutants (criteria pollutants); first national law for air pollution control

Primary sources of criteria air pollutants

power generation sector and transportation sector

Compounds of sulfur

second to PM from smoke in damage to human health by air pollutants

Carbon monoxide

colorless, odorless, highly toxic gas; result of incomplete fuel combustion

Effect of carbon monoxide exposure

inhibits respiration by binding to hemoglobin in blood

Effect of lead exposure

impaired nerve and brain functions

Criteria pollutants

contribute the most to air quality degradation; include carbon monoxide, nitrogen oxides, ground-level ozone, sulfur dioxide

Criteria pollutant sources

vehicles, power plants

Major components of acid precipitation

nitric acid, sulfuric acid

Ground-level ozone

three-atom molecule of oxygen; formed when volatile organic compounds react with other pollutants in the presence of sunlight

Main source of lead pollution

gasoline with lead; banned and phased on in 1980s

Hazardous air pollutants

toxins specially regulated in the Clean Air Act; can have adverse impacts on human health at low doses; includes carcinogens, neurotoxins, mutagens, teratogens, and endocrine disrupters; environmentally persistent

Coal-burning power plants

where 70% of airborne mercury comes from

Primary sources of mercury in atmosphere

coal combustion, smelting, waste combustion

Primary sources of black carbon in the atmosphere

fossil fuel combustion, burning biofuels, burning biomass

Ozone hole

thinning of stratospheric ozone concentrations due to chlorine-based aerosols

Greenhouse gas related supreme court ruling 2007

EPA’s responsibility to limit greenhouse gases on grounds of public health and welfare within meaning of the Clean Air Act

Montreal Protocol

international agreement to phase out use of ozone-destroying CFCs by 2000; goal to restore stratospheric ozone

Black carbon effect on climate

absorbs solar energy in atmosphere; decreases albedo of snow and ice

Acidic precipitation due to

nitrogen oxides, sulfates, sulfur dioxide

Particulate removal techniques

employing electrostatic precipitators, filtering air using a mesh of material (eg cotton cloth)

Cap-and-trade

market-based system allowing companies to buy and sell pollution credits; sets maximum allowed emission levels but if it isn’t reached, the remaining “space” can transfer

Particulate removal

filtering of emissions to remove ash from effluent gas after burning

Electrostatic precipitators

filter air emissions from factories

Volatile organic compounds

easily evaporated carbon-based compounds; interact with ozone to produce smog

Mercury

airborne metal pollutant; mainly from combustion; neurotoxin; human exposure from eating fish (bioaccumulation)

2007 US Supreme Court - Mass. v EPA

EPA can regulate emissions of 6 greenhouse gases as pollutants under Clean Air Act

Pollutants/dangers of indoors

Radon (radioactive gas from natural uranium decay in environment; second leading cause of lung cancer), cigarette smoke, molds, pathogens, soot, higher toxic pollutant concentrations (chloroform, benzene, styrene (70% higher than outdoors))

Sulfur oxides

colorless, corrosive gas, reacts with water vapor to form sulfuric acid

Nitrogen oxides

highly reactive gases, react with water vapor to form nitric acid, combustion initiates reactions between atmospheric nitrogen and oxygen

Ecological effects of acid deposition (forests)

mobilizes heavy metals in soils, makes soils acidic (fallen pine needles are acidic)

Ecological effects of acid deposition (ag)

SO2 destroys chlorophyll, impacts plant growth

Great London Smog (1952)

smoke, fog, temp inversion.. Killed 4700 people over 4 days, SO2 concentrations 25x current EPA limits

Acid deposition impacts lakes

disrupts fish reproduction (young die below ph5),

Acid deposition impacts buildings/structures

acids dissolve things built with marble and limestone, corrodes steel, reinforced concrete (with steel bars) used in bridges and roads

Solutions to acid deposition

neutralize acid in field (“liming”), scrubbers on smokestacks (neutralize before emission), reduce use of high-sulfur coal (cleaner sources) cap and trade

Ozone

good and bad; necessary part of stratosphere for life; tropospheric pollutant irritates/damages eyes, lungs, plant tissues; highly reactive oxidizing agent

Formation of ground-level ozone

VOCs + NOx + solar radiation → ozone and other photochemical oxidants

Solutions to ground-level ozone

cleaner burning fuels (ethanol blends) , better equipment on vehicles, (catalytic converters to cut NOx emissions), reduce number of vehicle (transit systems)