1. Air & Air Pollution
Chapter 12, Section 1: What Causes Air
Pollution?
Standards: SEV3a

2. What is the normal composition
of air?
 78% Nitrogen
 21% oxygen
 1% various other
gases like
◦ Argon
◦ Carbon dioxide
◦ Water vapor

3. What is air pollution?
 Any harmful
substance that
builds up in the air to
unhealthy levels.
 Can be natural:
pollen, dust, gases
from volcanoes
 Mostly human
caused: car
exhaust, coal-fired
power plants,
industrial pollution,
etc.

4. What is the difference between a
primary and secondary
pollutant?
 Primary pollutant
◦ Put directly into air by
human activities
 Ex: Sulfur dioxide
released from burning
fossil fuel.
 Secondary pollutant
◦ Primary pollutants
react with other
primary pollutants or
water vapor to make a
new substance
 Ex: Sulfur dioxide
mixes with water in
atmosphere and causes
acid rain.

5. What are the 5 primary air
pollutants?
1. Carbon monoxide
2. Nitrogen oxides
3. Sulfur dioxides
4. Volatile Organic
Compounds
5. Particulate Matter

6. 1. Carbon Monoxide (CO)
 Description:
◦ Odorless, colorless
◦ Poisonous
◦ From incomplete
combustion of fossil fuels
 Primary Source:
◦ Vehicles (cars, trucks,
buses)
◦ Industrial processes
 Effects:
◦ Blood can’t carry oxygen
as well, feel sleepy &
disoriented; can cause

7. 2. Nitrogen Oxides (NOx)
 Description:
◦ Can be yellowish gas
◦ Forms under high temps
 Primary Source:
◦ Vehicles (cars, trucks,
buses)
◦ Power plants
◦ Industrial boilers
 Effects:
◦ Brownish haze from smog
comes from NOx
◦ Some acid precipitation
◦ Makes body vulnerable to
respiratory disease &
cancer

8. 3. Sulfur dioxides (SO2)
 Description:
◦ Pungent smell
 Primary Source:
◦ Burning fossil fuels
 Power plants
 Refineries
 Smelters
◦ Volcanic activity
 Effects:
◦ Contributes to acid rain
◦ Harm plants
◦ Irritate respiratory system

9. 4. Volatile Organic Compounds
(VOCs)
 Description:
◦ Organic chemicals
◦ Vaporize readily
◦ Form toxic fumes
 Primary Source:
◦ Vehicles (cars, trucks,
buses)
◦ Burning fossil fuels
 Effects:
◦ Contribute to smog
formation
◦ Harm plants
◦ Linked to cancer

10. 5. Particulate Matter (PM)
 Description:
◦ Tiny pieces of liquid or solid
matter
 Primary Source:
◦ Construction, agriculture,
forestry, fires
◦ Vehicles, power plants &
Industrial processes
 Effects:
◦ Form clouds & reduce
visibility
◦ Small pieces can be inhaled
& clog respiratory system
◦ Linked to cancer
◦ Corrode metal & erode
buildings
Divided into:
Fine particulate matter (PM 2.5)-
from burning fossil fuels; worst
because can be inhaled deeper
into lungs
Coarse particulate matter
(PM10)- incinerators, mining,
cement plants

11. How long have air pollution
problems been around?
 As early as 2000
years ago, people
complained of “foul
air”
 Air pollution
problems became
worse around the
Industrial Revolution
of the 1800’s when
fossils fuel usage
increased and no
standards existed for
how much pollution
Weather History: The Great Smog
of 1952- London

12. What are two main sources of air
pollution?
1. Motor Vehicle
Emissions
2. Industrial Air
Pollution

13. What are Motor Vehicle
Emissions?
 Fumes & particulates
produced from the burning
of gasoline in vehicles
 1/3 of air pollution comes
from gasoline burned by
vehicles.
 Clean Air Act-
◦ regulates vehicle emissions
◦ Banned lead in gasoline-
lead pollution has decreased
by 90% in US.
◦ Catalytic converters clean
exhaust gas
 EPA says vehicles today
burn fuel 35% more
efficiently and with 95 %
fewer emissions (except
CO2) than they did 30
years ago.

14. What are Zero-Emissions
Vehicle (ZEV) Programs?
 Established in CA,
MA, ME, NY, & VT
 Offer rebates, tax
incentives, closer
parking, use of
special HOV type
lanes for ZEVs
 Types of ZEVs:
◦ Electric cars- plug in to
recharge
◦ Hybrid cars- run on
both gas and electric
◦ Methanol fuel cell cars

15. What are Industrial Air
Pollutants?
 Any industry or
power plant that
burns fuel to
produce energy
 Power plants
produce
◦ 2/3 of all SO2
emissions
◦ 1/3 of all NOx
emissions
 VOCs are common
type
◦ From dry cleaning
fumes

16. What are Industrial Air
Pollutants?
 Clean Air Act
requires one of the
following:
◦ Scrubbers installed in
smoke stacks to
control air pollution
 Gases move through
spray of water that
dissolves the pollutant
◦ Electrostatic
Precipitators
 Use static electricity to
attract particulates from
burning of fossil fuels

17. What is smog?
 Air pollution that
hangs over urban
areas and reduces
visibility.
 Car exhaust reacts
with air & sunlight to
make ground level
ozone.
 Ozone reacts with
more car exhaust to
make smog.
 Smog in Beijing,
China (~2min)

18. What is a Temperature
Inversion?
 Circulation keeps air
pollution from reaching
dangerous levels.
 If a warm air mass traps a
cool air mass it will trap
pollution with it.
 Usually common in cities
surrounded on 3 sides by
mountains.
 Mountains trap the air.
 Donora, PA (1948)- 18
people died when
temperature inversion
trapped SO2 & HF pollution
being released from a local
steel mill.

19. You should be able to…
 Name 5 primary pollutants & give
important sources for each.
 Name the 2 major sources of air
pollution in urban areas.
 Describe the way in which smog
forms.
 Define the term temperature inversion.
Explain how temperature inversion
traps pollutants near Earth’s surface.