Air PollutionAir Pollution

Environmental ScienceEnvironmental Science

What Causes Air Pollution?What Causes Air Pollution? Air Pollution is the contamination of the Air Pollution is the contamination of the

atmosphere by solid, liquid, or gassesatmosphere by solid, liquid, or gasses Most air pollution is the result of human activities Most air pollution is the result of human activities

– Industrial burningIndustrial burning– Automobile ExhaustAutomobile Exhaust

Some pollutants are Some pollutants are

naturalnatural– DustDust– Pollen and sporesPollen and spores– Volcanic eruptions (sulfur Volcanic eruptions (sulfur

dioxide)dioxide)

Primary and Secondary Primary and Secondary PollutantsPollutants

Primary Pollutants – a pollutant put directly Primary Pollutants – a pollutant put directly into the atmosphere by humans or natureinto the atmosphere by humans or nature– Ex. CO from car exhaustEx. CO from car exhaust

Secondary Pollutants – a pollutant that is Secondary Pollutants – a pollutant that is formed by a chemical reaction between a formed by a chemical reaction between a primary pollutant and another compound primary pollutant and another compound in the atmosphere (either natural or man-in the atmosphere (either natural or man-made)made)– Ex. Ground level ozoneEx. Ground level ozone

Types of PollutantsTypes of Pollutants Carbon monoxide (CO)Carbon monoxide (CO)

– mainly comes from car exhaust mainly comes from car exhaust Nitrogen oxides (NONitrogen oxides (NOXX))

– auto exhaust, power plants and some industrial auto exhaust, power plants and some industrial processesprocesses

Sulfur dioxide (SOSulfur dioxide (SO22))– burning fossil fuelsburning fossil fuels

Volatile Organic Compounds (VOCs)Volatile Organic Compounds (VOCs)– burning fuel (gasoline vapors)burning fuel (gasoline vapors)

Particulate Matter Particulate Matter – tiny particles (can be solids or liquids) – tiny particles (can be solids or liquids) –

construction, agriculture, fires, vehicles, construction, agriculture, fires, vehicles, industry industry

Automobile EmissionsAutomobile Emissions

One third (1/3) of One third (1/3) of air pollution comes air pollution comes from carsfrom cars

Americans drove Americans drove 2.6 trillion miles in 2.6 trillion miles in 19981998– Only 10% of that Only 10% of that

was done by busses was done by busses or trucksor trucks

Clean Air Act of 1970Clean Air Act of 1970

Gives the EPA authority to regulate Gives the EPA authority to regulate automobile emissionsautomobile emissions

The EPA required:The EPA required:– Elimination of leaded gasolineElimination of leaded gasoline

Lead pollution has decreased 90% as a resultLead pollution has decreased 90% as a result

– Catalytic converters had to be installed into Catalytic converters had to be installed into carscars Cause a chemical reaction that changes the Cause a chemical reaction that changes the

pollutants to less harmful substancespollutants to less harmful substances

EPA estimates cars burn fuel 35% more EPA estimates cars burn fuel 35% more efficiently and pollute 95% less now than efficiently and pollute 95% less now than 30 yrs ago30 yrs ago

Zero-Emission VehicleZero-Emission Vehicle California began the Zero-Emission Vehicle California began the Zero-Emission Vehicle

program to encourage the development of program to encourage the development of less-polluting vehiclesless-polluting vehicles– Electric cars are the only true ZEV carsElectric cars are the only true ZEV cars– 2 types of partial ZEV’s2 types of partial ZEV’s

Gasoline/Electric Hybrids (Toyota Prius)Gasoline/Electric Hybrids (Toyota Prius) Methanol Fuel Cells (all still prototypes)Methanol Fuel Cells (all still prototypes)

Industrial PollutionIndustrial Pollution Most power plants generate electricity by Most power plants generate electricity by

burning fossil fuelsburning fossil fuels

Power plants emit at least 2/3 of all sulfur Power plants emit at least 2/3 of all sulfur dioxide and more than 1/3 of all nitrogen dioxide and more than 1/3 of all nitrogen oxides that pollute the air.oxides that pollute the air.

Dry cleaning, oil refineries, chemical Dry cleaning, oil refineries, chemical manufacturing plants, furniture refinishers, manufacturing plants, furniture refinishers, and automobile repair shops all contribute and automobile repair shops all contribute to the VOCs in the air.to the VOCs in the air.

Industrial Air PollutionIndustrial Air Pollution Clean Air Act also requires Clean Air Act also requires

that industries remove that industries remove pollution from their pollution from their emissionsemissions

ScrubbersScrubbers – remove gasses – remove gasses by spraying water into the by spraying water into the exhaust to dissolve many exhaust to dissolve many soluble pollutantssoluble pollutants

Electrostatic Electrostatic PrecipitatorsPrecipitators – gasses – gasses containing dust particles are containing dust particles are blown through an electrically blown through an electrically charged chamber – the dust charged chamber – the dust sticks to each other and the sticks to each other and the side of the chamberside of the chamber– 20 tons of ash generated by 20 tons of ash generated by

coal burning power plants each coal burning power plants each yearyear

SmogSmog

Air pollution that hangs over cities and Air pollution that hangs over cities and reduces visibilityreduces visibility

Smog is the result of chemical reactions Smog is the result of chemical reactions involving sunlight, air, car exhaust, and involving sunlight, air, car exhaust, and ozoneozone

Temperature InversionsTemperature Inversions

Usually temperature decreases with altitude Usually temperature decreases with altitude A temperature inversion is when warm air is A temperature inversion is when warm air is

higher and the cold air is trapped beneathhigher and the cold air is trapped beneath Sometimes pollution is trapped beneath the warm Sometimes pollution is trapped beneath the warm

airair