Study Guide: Air Pollution and Climate Change
Key Terms
Pollution: Contamination of the environment (air, water, soil) by harmful substances, often from human activity.
Electrostatic Precipitator: A device that removes particulate matter (PM) from industrial exhaust by using electric charges to attract and collect particles.
VOC’s (Volatile Organic Compounds): Organic chemicals that evaporate easily (e.g., benzene, formaldehyde), contributing to ozone formation and air pollution.
Heat of Fusion: Energy required to change a substance from solid to liquid (e.g., melting ice), relevant to climate change as ice melts due to warming.
Point Source vs. Non-Point Source:
Point Source: Pollution from a single, identifiable source (e.g., a factory smokestack).
Non-Point Source: Diffuse pollution from multiple sources (e.g., runoff from farms).
PM / Particulate Matter: Tiny solid or liquid particles in the air (e.g., PM10, PM2.5), from sources like dust, smoke, or combustion.
CFC’s / Chlorinated Fluorocarbons: Synthetic compounds once used in refrigerants/aerosols that deplete stratospheric ozone.
Troposphere: Lowest atmospheric layer (up to ~10 km), where weather occurs and most pollutants reside.
Stratosphere: Layer above the troposphere (10-50 km), containing the ozone layer that shields Earth from UV radiation.
Paris Accord / Agreement (2015): Global pact to limit warming to below 2°C, with voluntary national commitments.
Kyoto Protocol (1992): Earlier treaty setting binding emission reduction targets for developed nations.
Greenhouse Effect: Trapping of heat in Earth’s atmosphere by gases like CO2, CH4, and H2O, warming the planet.
Albedo: Measure of reflectivity; high albedo (e.g., ice) reflects sunlight, low albedo (e.g., water) absorbs it.
IPCC (Intergovernmental Panel on Climate Change): UN body assessing climate science and solutions.
Mitigation: Actions to reduce or prevent greenhouse gas emissions (e.g., renewable energy adoption).
Cap and Trade on Carbon Emissions: System where companies get a carbon "cap" and can trade unused allowances, incentivizing reductions.
Weather vs. Climate:
Weather: Short-term atmospheric conditions (e.g., today’s rain).
Climate: Long-term average patterns (e.g., 30-year temperature trends).Concepts and Questions
In which layer of the atmosphere does weather occur?
Answer: Troposphere. It’s the lowest layer where temperature, pressure, and moisture interact to create weather.
What are the six EPA Criteria Air Pollutants? Major source for at least three?
Answer:
Particulate Matter (PM) – Source: Vehicle exhaust (transportation).
Ground-Level Ozone (O3) – Source: Car emissions + sunlight (transportation).
Carbon Monoxide (CO) – Source: Incomplete combustion in cars (transportation).
Sulfur Dioxide (SO2) – Source: Coal power plants (industry).
Nitrogen Dioxide (NO2) – Source: Vehicle exhaust (transportation).
Lead (Pb) – Source: Historically, leaded gasoline (transportation).
Why is ozone a benefit in the stratosphere but a problem in the troposphere?
Answer: In the stratosphere, ozone absorbs harmful UV radiation, protecting life. In the troposphere, it’s a pollutant that irritates the lungs and damages plants, formed from VOCs and NOx in sunlight.
Which particulates are considered more dangerous to health, large or small? Why?
Answer: Small (e.g., PM2.5, <2.5 micrometers). They penetrate deeper into lungs and bloodstream, causing respiratory and cardiovascular issues, unlike larger particles (e.g., PM10) which are filtered by the nose.
Which greenhouse gas has the greatest effect? Why is this a complicated question?
Answer: Carbon dioxide (CO2) has the greatest overall effect due to its abundance (423 ppm in 2024) and long atmospheric lifetime (hundreds of years). However, it’s complicated because methane (CH4) is 25x more potent per molecule but less abundant, and water vapor amplifies warming but isn’t directly emitted by humans. Potency, quantity, and lifespan vary (see hypothetical table: CO2 = high volume, CH4 = high potency).
Which legal act primarily protects air quality?
Answer: The Clean Air Act (1970, amended 1990) in the U.S. regulates air pollutants like the EPA’s Criteria Pollutants.
Which pollutants are reduced by catalytic converters in cars?
Answer: Carbon monoxide (CO), nitrogen oxides (NOx, including NO2), and volatile organic compounds (VOCs), converted into less harmful CO2, N2, and H2O.
How was lead pollution significantly reduced in the 1970s?
Answer: Phasing out leaded gasoline under the Clean Air Act, starting in 1975, reduced emissions from transportation.
What is the Paris Accord? What happens if a country fails to meet its goal?
Answer: A 2015 agreement to limit global warming to below 2°C via voluntary Nationally Determined Contributions (NDCs). No strict penalties exist—failure leads to diplomatic pressure or reputational damage, not legal consequences.
How does the melting of sea ice and glacial ice increase the warming of the planet?
Answer: Melting lowers albedo (ice reflects ~80% of sunlight, water absorbs ~90%), so less heat is reflected back to space, accelerating warming in a feedback loop.
Why would a cap and trade system be an easier way to get companies to reduce emissions than simple penalties?
Answer: It creates an economic incentive—companies profit by selling unused carbon allowances, whereas penalties only punish without reward, making compliance more appealing.
What is the relationship between carbon dioxide concentration in the atmosphere, ocean CO2 concentration, and ocean pH? Why is ocean pH important? Which organisms are most affected?
Answer: Higher atmospheric CO2 increases ocean CO2 absorption, forming carbonic acid and lowering pH (ocean acidification). Ocean pH matters for marine ecosystems—coral reefs and shellfish (e.g., oysters, clams) suffer most as acidic water dissolves their calcium carbonate structures.
What have carbon dioxide levels looked like over the past 800,000 years?
Answer: CO2 fluctuated between ~180 ppm (ice ages) and ~280 ppm (warm periods) in natural cycles, per ice core data. Since the Industrial Revolution (~1750), levels spiked to 423 ppm (2024), far exceeding historical highs.
How do carbon dioxide concentrations and temperature compare? Do they follow the same patterns, or not?
Answer: They generally follow the same pattern—higher CO2 correlates with higher temperatures (e.g., ice core data shows CO2 and temp rising/falling together over 800,000 years). Post-1750, both skyrocketed due to human emissions, though temperature lags slightly due to ocean heat absorption.
In which layer of the atmosphere does weather occur?
Answer: Troposphere. It’s the lowest layer where temperature, pressure, and moisture interact to create weather.
What are the six EPA Criteria Air Pollutants? Major source for at least three?
Answer:
Particulate Matter (PM) – Source: Vehicle exhaust (transportation).
Ground-Level Ozone (O3) – Source: Car emissions + sunlight (transportation).
Carbon Monoxide (CO) – Source: Incomplete combustion in cars (transportation).
Sulfur Dioxide (SO2) – Source: Coal power plants (industry).
Nitrogen Dioxide (NO2) – Source: Vehicle exhaust (transportation).
Lead (Pb) – Source: Historically, leaded gasoline (transportation).
Why is ozone a benefit in the stratosphere but a problem in the troposphere?
Answer: In the stratosphere, ozone absorbs harmful UV radiation, protecting life. In the troposphere, it’s a pollutant that irritates the lungs and damages plants, formed from VOCs and NOx in sunlight.
Which particulates are considered more dangerous to health, large or small? Why?
Answer: Small (e.g., PM2.5, <2.5 micrometers). They penetrate deeper into lungs and bloodstream, causing respiratory and cardiovascular issues, unlike larger particles (e.g., PM10) which are filtered by the nose.
Which greenhouse gas has the greatest effect? Why is this a complicated question?
Answer: Carbon dioxide (CO2) has the greatest overall effect due to its abundance (423 ppm in 2024) and long atmospheric lifetime (hundreds of years). However, it’s complicated because methane (CH4) is 25x more potent per molecule but less abundant, and water vapor amplifies warming but isn’t directly emitted by humans. Potency, quantity, and lifespan vary (see hypothetical table: CO2 = high volume, CH4 = high potency).
Which legal act primarily protects air quality?
Answer: The Clean Air Act (1970, amended 1990) in the U.S. regulates air pollutants like the EPA’s Criteria Pollutants.
Which pollutants are reduced by catalytic converters in cars?
Answer: Carbon monoxide (CO), nitrogen oxides (NOx, including NO2), and volatile organic compounds (VOCs), converted into less harmful CO2, N2, and H2O.
How was lead pollution significantly reduced in the 1970s?
Answer: Phasing out leaded gasoline under the Clean Air Act, starting in 1975, reduced emissions from transportation.
What is the Paris Accord? What happens if a country fails to meet its goal?
Answer: A 2015 agreement to limit global warming to below 2°C via voluntary Nationally Determined Contributions (NDCs). No strict penalties exist—failure leads to diplomatic pressure or reputational damage, not legal consequences.
How does the melting of sea ice and glacial ice increase the warming of the planet?
Answer: Melting lowers albedo (ice reflects ~80% of sunlight, water absorbs ~90%), so less heat is reflected back to space, accelerating warming in a feedback loop.
Why would a cap and trade system be an easier way to get companies to reduce emissions than simple penalties?
Answer: It creates an economic incentive—companies profit by selling unused carbon allowances, whereas penalties only punish without reward, making compliance more appealing.
What is the relationship between carbon dioxide concentration in the atmosphere, ocean CO2 concentration, and ocean pH? Why is ocean pH important? Which organisms are most affected?
Answer: Higher atmospheric CO2 increases ocean CO2 absorption, forming carbonic acid and lowering pH (ocean acidification). Ocean pH matters for marine ecosystems—coral reefs and shellfish (e.g., oysters, clams) suffer most as acidic water dissolves their calcium carbonate structures.
What have carbon dioxide levels looked like over the past 800,000 years?
Answer: CO2 fluctuated between ~180 ppm (ice ages) and ~280 ppm (warm periods) in natural cycles, per ice core data. Since the Industrial Revolution (~1750), levels spiked to 423 ppm (2024), far exceeding historical highs.
How do carbon dioxide concentrations and temperature compare? Do they follow the same patterns, or not?
Answer: They generally follow the same pattern—higher CO2 correlates with higher temperatures (e.g., ice core data shows CO2 and temp rising/falling together over 800,000 years). Post-1750, both skyrocketed due to human emissions, though temperature lags slightly due to ocean heat absorption.