7.1 - Introduction to Air Pollution (Pollutants)

Question 1

Air Pollution Basics

Answer 1

• Write about air pollutants (specific/particles) not just air “pollution” as an idea
• Clean Air Act (1970) - identified 6 criteria air pollutants that the EPA is required to set scceptable limits for, monitor, and enforce

Question 2

Air Pollutants

Answer 2

• Sulfur Dioxide (SO2):
  - Source: Coal Combustion (electricity)
  - Causes: Respp. Irr, Smog, acid precip
• Nitrogen Oxides (NOx):
  - Source: All Fossil Fuels (Gas especially)
  - Causes: O3, photchemical smog, acid precip
• Carbon Monoxide (CO):
  - Sources: Incomplete combution
  - Causes: O3, lethal to humans
• Particulate Matter (PM)
  - Source: Fossil Fuels, Biomass combustion
  - Causes: Resp Irr, Smog
• Ozone (O3):
  - Source: Photochemical oxidation of NO
  - Causes: Resp Irr, smog, plant damage
• Lead (Pb)
  - Sources: Metal plants, inceineration
  - Causes: Neurotoxicant

Question 3

Ai Pollutants vs GHG

Answer 3

• CO2 is not one of 6 criteria pollutants in CAA
• CO2 does not directly lower air quailty from a human health standpoint
  - not toxic to organisms resp
  - not damaging to lungs and eyes
  - Does not lead to smog, decreased visability
• CO2 is a GHG, it does lead to global warming and thus environmental and human health consequences
• Botom LIne: In APES CO2 has not typically been included on FRQ scoring guides as an air pollutant
  - Stick to fire air pollutants: SO2, NOx, O3, PM

Question 4

Coal Combustion

Answer 4

• Reelases mor air pollutants than other FF (about 35% of global electricity)
• Releases CO, CO2, SO2, NOx, toxic metals (mercury, arsenic, lead) and PM (often carries the toxic metals)

Question 5

Impacts of SO2

Answer 5

• Respiratory irritant (inflamation of bronchioles, lungs), worsens asthma and bronchitis
• Sulfur aerosols (suspendedsulfate particles) block incoming sun, reducingvisibility and photosynthesis
• Forms sulfurous (grey) smog
• Combiens with water and O2 in atmosphere to form sulfuric acid = acid precipitation

Question 6

Nitrogen Oxides (NOx)

Answer 6

• Released by combustion of anything especially FFs and biomass
• NOx refers to nitrogen oxides (both NO and NO2)
• NO forms when N2 combines with O2 (especially during combustion)
• NO can become NO2 by reacting with O3 or O2
• Sunlight converts NO2 back into NO
• environmental and human health impacts
  - repsiratory irritant
  - leads to tropospheric ozone formation, which leads to photohemical smog
  - combines with water and )2 in atmosphere to form nitric acid = acid precipitation

Question 7

EPA and Lead

Answer 7

• Before CAA, lead was a common gasoline additive; EPA began phaseout of lead from gasoline in 1974
• Vehicles made after 1974 are required to have catalytic converters to reduce NOx, CO and hydrocarbon emissions (lead damages catalytic converters)
  - also a known neurotoxin (damages nervous systems of humans)

Question 8

Primary vs Secondary Air Pollutants

Answer 8

Primary:
- Emitteddirectly from sources such as vehicles, power plants, factories, or natural sources (volcanoes, forest fires)
- NOx, CO, VOCs, SO2, PM, hydrocarbons

Secondary:
- Primary pollutants that have transformed in presence of sunlight, water, O2
- Occur more during the day (since sunlight often drives formation)
- Tropospheric O3
-Sulfiric acid (H2SO4) and sulfate (SO4-2)
- Nitric acid (HNO3) and nitrate (NO3-1)