Bellringer
• Define “air pollution”.
• What types of things count as “air
pollution”?
• What does polluted air look like?
• What do you think is the biggest
source of air pollution in cities?
#15 - What Causes Air
Pollution?
Section 12.1
Objectives:
1. Name 5 primary air pollutants,
and give sources for each.
2. Name the 2 major sources of air
pollution in urban areas.
3. Describe how smog forms.
Define “air pollution”
• When harmful substances build up in
the air to unhealthy levels.
– Human activities
– Natural sources
• Compare cigarette smoke and
pollution (Lanzhou, China)
• Cigarette manufacturers vs.
industries – legal responsibilities
Primary and Secondary
Pollutants
• Primary pollutants: a pollutant put directly
•
into the air by human activity (EX: soot
from smoke)
Secondary pollutant: forms when a primary
pollutant comes into contact with other
primary pollutants or with naturally
occurring substances, such as water vapor,
and a chemical reaction takes place (EX:
ground-level ozone formed from vehicle
emissions reacting with UV rays and mixing
with oxygen)
What color is polluted air?
• Primary Air Pollutants (Table 1, p.304)
Sources of Primary Air Pollutants
(Fig.1, p.303)
Smog
• Definition: pollution that hangs over
urban areas and reduces visibility
•
Smog is formed when:
1. Car emissions combine with sunlight
and air to form ozone.
2. Car emissions + ozone = smog
•
What is the importance of ozone
alerts?
•
“Valley of the Smokes” - LA
Temperature Inversion
• How does temperature change with
elevation?
• When warm air rises, it carries air
pollutants with it, removing them
from air at the surface.
• Temperature inversion: the air above
is warmer than the air below.
• The warmer air above traps the cooler
air (and pollutants) at the surface.
Reducing Air Pollution
• King Edward II (1273): “Off with his
head!”
• What attempts can you think of that
have been used to try to reduce air
pollution?
Regulating Motor Vehicle
Emissions
• Clean Air Act (1970; 1990)
– EPA regulates vehicle emissions
– Leaded gasoline
• Zero-Emission Vehicle Programs
– Electric vehicles
– Advanced battery vehicles
– Hydrogen fuel
– Partial zero-emissions vehicles
Industrial Air Pollution
• How do factories and power plants
make electricity?
• Power plants the produce electricity
ALSO produce 2/3 of all sulfur
dioxide and 1/3 of all nitrogen oxides
that pollute the air.
• Clean Air Act requires many
industries to “scrub” or filter their
emissions – spray the gases with
water to dissolve pollutants.
Group Discussion
• How do you contribute to air
pollution?
• At what point would the level of air
pollutants be high enough for you to
take action?
• Should automobile makers be made to
adhere to quotas of zero-emission
vehicles set by states, even if the
quota causes automakers to lose
revenues? Support your stand.
Review
• On the board, list as many causes of
air pollution as possible.
• Exit Slip Assignment: Place the
causes in the appropriate category.
(NOTE: Causes may fall into more
than one category.):
1. Industrial and Commercial
2. Transportation
3. Noncommercial
KNOW FOR TEST!!!
• Section Review questions 1-4 (p.308)