Air & Air PollutionChapter 12, Section 1: What Causes Air Pollution?Standards: SEV3a
What is the normal composition of air?78% Nitrogen21% oxygen1% various other
gases like◦ Argon◦ Carbon dioxide◦ Water vapor
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.
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.
What are the 5 primary air pollutants?
1. Carbon monoxide
2. Nitrogen oxides3. Sulfur dioxides4. Volatile Organic
Compounds5. Particulate
Matter
1. Carbon Monoxide (CO)Description:
◦ Odorless, colorless◦ Poisonous◦ From incomplete
combustion of fossil fuelsPrimary Source:
◦ Vehicles (cars, trucks, buses)
◦ Industrial processesEffects:
◦ Blood can’t carry oxygen as well, feel sleepy & disoriented; can cause death
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
3. Sulfur dioxides (SO2)Description:
◦ Pungent smellPrimary Source:
◦ Burning fossil fuels Power plants Refineries Smelters
◦ Volcanic activityEffects:
◦ Contributes to acid rain◦ Harm plants◦ Irritate respiratory
system
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
5. Particulate Matter (PM)
Description:◦ Tiny pieces of liquid or solid
matterPrimary 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 lungsCoarse particulate matter (PM10)- incinerators, mining, cement plants
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 could be emitted.
Weather History: The Great Smog of 1952- London
What are two main sources of air pollution?
1. Motor Vehicle Emissions
2. Industrial Air Pollution
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.
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
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◦ Oil refineries◦ Chemical plants◦ Car repair shops
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
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)
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.
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.
