Post on 15-Jul-2015
What is the normal composition
of air?
78% Nitrogen
21% oxygen
1% 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 oxides
3. Sulfur dioxides
4. Volatile Organic
Compounds
5. Particulate Matter
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 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 smell
Primary Source:
◦ Burning fossil fuels Power plants
Refineries
Smelters
◦ Volcanic activity
Effects:
◦ 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
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
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 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
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.