Chapter 12.1

AIR POLLUTION – when harmful

substances in air built up to an unhealthy

level

These can be solids, liquids or gases

PRIMARY – directly from humans • Soot from smoke (the black dust)

SECONDARY – when primary pollutants

come in contact with other pollutants or

naturally occurring substances • Ground-level ozone (car emissions mix with

oxygen and react with sun rays)

Power plants, household products, cars

are major sources

Most of the chemicals are carbon

monoxide, nitrogen oxide, sulphur

dioxide, and volatile organic compounds

(VOCs)

Vehicles produce carbon monoxide and

nitrogen oxide

vehicles and gas station spillage are

sources of VOCs

Air pollution is not

new

Anytime anything

burns it creates

pollution

Burning sea-coal was

made illegal in 1200s

because of pollution

• 1/3 of air pollution comes from vehicle

emissions

• Clean Air Act in USA in 1970 (made stronger in

1990)

• Eliminated lead in gasoline

• Mandatory catalytic converters in cars to clean

exhaust

In 1990 California started a program

developing cars with no emissions (ex.

hydrogen fuel, hybrid-electric cars,

methanol fuel cells)

Many places are now doing the same

Power plants burn fuel to generate

energy

Usually burn fossil fuels in huge

quantities

Produce nitrogen oxide and sulphur

dioxide • 2/3 of all global sulphur dioxide

• 1/3 of all global nitrogen oxide

Must have scrubbers

which remove

chemicals

Electrostatic

precipitators remove

dust (these remove

20 million tons of dust

a year!)

SMOG – pollution

that remains in air

above urban areas

and reduces visibility

Results from a

chemical reaction of

pollutant and sunlight

When pollution is trapped near surface

Creates cool air on ground by

TEMPERATURE INVERSION

Traps smog in cities located in valleys • Ex. Los Angeles, Mexico City, Seoul