2. Air Pollution
● air pollution- the contamination of the
atmosphere by the introduction of
pollutants from human and natural
sources
○ classified as primary or
secondary pollutants
● can cause death of many people
○ burns people's lungs
● very common throughout the world
3. London's "Pea Souper" Fog
● Occurred in 1952
● Killed thousands of people
● Caused major changes in air-
pollution laws
4. Primary Pollutants
● primary pollutants- pollutants put
directly into the air by human or
natural activity
● come from natural sources
○ Examples:
■ dust
■ sea salt
■ volcanic gases and ash
■ smoke from forest fires
■ pollen
● come from human sources
○ Examples:
■ carbon monoxide
■ dust
■ smoke
■ chemicals
■ vehicle exhaust
5. Secondary Pollutants
● secondary pollutants- formed
when primary pollutants react
with primary pollutants or other
natural substances
● examples:
○ automobile exhaust
○ ozone
○ smog
● "Ozone Action Day"
○ when people are
discouraged from doing
outdoor activities
○ when smog or air conditions
are so bad it could damage
your lungs
6. The Formation of Smog
● smog- forms when sunlight mixes
with ozone and vehicle exhaust
● Increases when mountains
surround an area
● Common in Los Angeles
