15
At
15. 2ppt
Air Quality
CH 15 Prentice Hall
p.504-508
What is Air Pollution?
• A brown haze or unpleasant
smell
• Pollutants= harmful
substances in the air, water
or soil.
Particles
• Air contains particles (pollutants) as well as
gases.
• Come from both natural sources and human
activities.
Natural Causes
• The Ocean- water evaporates and
leaves tiny salt particles in the air.
• Particles of mold and plant pollen
–blown by the wind.
• Forest Fires
Natural Causes
• Soil Erosion
• Dust Storms
• Volcanoes- erupt dust, ash and
poisonous gases
Human Activities
• Most is caused by human activities
– Burning Fossil Fuels
•
•
•
•
Oil
Gasoline
Diesel Fuel
Coal
• Burning Wood and Coal
– releases particles of carbon into the air.
– These particles of soot give smoke its dark color.
Human Activities
• Farming activities and construction release
large amounts of soil particles into the air.
– Due to soil erosion.
• ½ of pollution comes from cars/motor
vehicles.
• ¼ of pollution comes from factories and power
plants that burn coal & oil.
Smog
• In 1905-smoke and fog combined and formed
London-type smog. It occurs when water
droplets combine with coal smoke (soot) in
humid air.
• No longer common in the US.
Photochemical “Smog”
• Photochemical smog forms a brown haze.
– “Photo”= Light
– Caused by the action of sunlight on chemicals
(nitrogen oxides and hydrocarbons), producing a
mix of ozone and other chemicals.
• Los Angeles and Mexico City
Temperature Inversion
• Normally warm air close to the surface is
heated and rises carrying pollutants with it
and are blown away.
Temperature Inversion
• During a temp inversion, A layer of warm air
that prevents the rising air from escaping and
polluted air is trapped and held close to the
surface. It becomes concentrated and
dangerous.
Acid Rain
• Forms when nitrogen oxides and other sulfur
oxides combine with water in the air to form
nitric acid and sulfuric acid.
– Rain, sleet, snow, fog and even dry particles carry
these two acids.
•
Acid Rain
• Rain is naturally
acidic but rain that
contains more than
normal is classified as
acid rain.
• Can damage the
surface of buildings
and statues.
• Can also effect living
organisms.
Improving Air Quality
• Many laws and regulations have been passed
by the federal and state governments.
• Pollution Control Devices required on cars
• Power Plants installed filters in smoke stacks
to remove smoke.
Improving Air Quality
• Air quality has improved in the last 30 years.
– Major air pollutants have decreased.
– Newer cars are less polluting. (hybrid cars)
– New power plants are less polluting.
• However, more cars are on the road and
more power plants burning fossil fuels.
• Air in cities is still polluted.
Effects of Air Pollution
• Dizziness and headaches
• Eye, nose, and throat irritation
– Cough
– Lung Disease
• Chest Pains
• Allergies
– Ragweed pollen causes “hay fever”
• Sneezing
• Runny nose
• Red itchy eyes.