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)
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