IB 105 Lecture 19

Know the types and proportions of the gases that make up the atmosphere.
78% nitrogen, 21% oxygen, 1% carbon dioxide, water, other gases
Distinguish between primary and secondary air pollutants.
primary: Materials that when released pose health risks in their unmodified forms
secondary: Primary pollutants interact with one another, sunlight, or natural gases to produce new, harmful compounds
What is photochemical smog, and how do thermal inversions contribute to the problem?
Secondary pollutants formed by reaction of nitrogen oxides and HC with sunlight
Includes ozone (O3)
destroys chlorophyll, injures lung tissue
ground-level ozone is “bad ozone”
Biggest problems in cities, mountains can make it even worse
Mountain ranges, wind directions lead to thermal inversions
when cool air is trapped below layer of warm air
pollutants accumulate, aren’t released to upper atmosphere
Why should we be concerned with indoor air pollution?
In U.S., 90% of time spent indoors; inside air often more polluted than outside air
Problems with weatherized building: little air exchange
Asbestos, carbon monoxide, formaldehyde, lead, pollen, dust, smoking
Causes diseases: emphysema, heart attacks, strokes, lung cancers
Distinguish between “bad” ozone and “good” ozone. What is causing depletion of the “good” ozone?
“bad”= closest to earth, air pollutant that is harmful “good”=stratosphere, protects from suns UV rays
Ozone Depletion, Ozone in the stratosphere is “good ozone”, Shields us from harmful ultraviolet light, Skin cancer and cataracts, depletion caused by chlorofluorocarbons from refrigerants, cleaning solvents, propellants
What does the Clean Air Act regulate, and how successful has it been?
Control requirements the federal government implements and states administer
All sources subject to ambient air quality regulation (NAAQS)
New sources subject to more stringent controls
Hazardous pollutants and visibility reducing emissions regulated
August 2003 changes reduce control
Since Clean Air Act passage, EPA reports air pollution cut by 1/3 and acid rain cut by 25%.
EPA estimates human health, welfare, and environmental benefits have outweighed costs by 40 to 1. Old coal-fired power plants and SUVs, diesel trucks and buses are still major problems
In which zone of the atmosphere does weather take place? Which contains ozone?
troposphere
stratosphere
What are the 5 major primary air pollutants,
Carbon monoxide:
Hydrocarbons
Particulate matter (2.5 mm and 10 mm)
Sulfur dioxide
Nitrogen oxides
Carbon monoxide, Where do they come from, and what problems do each cause?
Produced by burning of organic material (coal, gas, wood, trash, etc.), cigarette smoke, cars, Toxic because binds to hemoglobin, reduces oxygen in blood

Not a persistent pollutant, combines with oxygen to form CO2

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Most communities now meet EPA standards, but rush hour traffic can produce high CO levels

Hydrocarbons
Organic compounds with hydrogen, carbon, From incomplete burning or evaporated from fuel supplies, Major source is automobiles, but some from industry
Particulates
Small pieces of solid materials and liquid droplets (2.5 mm and 10 mm), Examples: ash from fires, asbestos from brakes and insulation, dust, Easily noticed: e.g. smokestacks
Can accumulate in lungs and interfere with the ability of lungs to exchange gases. Some particulates are known carcinogens, Those working in dusty conditions at highest risk (e.g., miners), pollution decreased 88% from 1970 – 2000
Sulfur Dioxide
Produced by burning sulfur containing fossil fuels (coal, oil)
When inhaled, can be very corrosive to lung tissue
London
1306 banned burning of sea coal
1952 “killer fog”: 4,000 people died in 4 weeks
tied to sulfur compounds in smog
Coal-burning power plants major source
Reacts in atmosphere to produce acids
One of the major components of acid rain
Nitrogen Oxides
Produced from burning of fossil fuels
Contributes to acid rain, smog
Automobile engine main source
New engine technology has helped reduce, but many more cars