8

The Dangerous Few: Air Pollutants

Carbon Monoxide (CO)

• Commonly known as the silent killer.

• Mechanism of Toxicity:

  • CO binds to hemoglobin in the blood more effectively than oxygen does.

• Initial Symptoms:

  • Dizziness

  • Nauseousness

• Consequences:

  • Can lead to death if exposure continues.

Ozone (O3)

• Effects on Health:

  • Reduces lung function.

• Symptoms:

  • Chest pain

  • Coughing

  • Sneezing

  • Lung congestion

Sulfur Dioxide (SO2)

• Chemical Behavior:

  • Dissolves in the moist tissues of the lungs to form an acid.

• At-Risk Populations:

  • Individuals who are young or old.

  • Those with pre-existing conditions such as emphysema or asthma.

Nitrogen Oxides (NOx)

• Chemical Behavior:

  • Also dissolves in the moist tissues of the lungs to form an acid.

• Physical Characteristics:

  • Exhibits a characteristic brown color that contributes to urban smog.

Lead (Pb)

• Health Effects:

  • Affects multiple systems in the body:

  • Central nervous system

  • Immune system

  • Reproductive and developmental systems

  • Cardiovascular system

• Vulnerable Populations:

  • Infants and young children are particularly sensitive.

  • Exposure may contribute to behavioral problems and learning deficits.

Particulate Matter (PM)

• Definition:

  • A complex mixture of tiny solid particles and microscopic liquid droplets.

• Classification:

  • Classified by particle size rather than chemical composition.

  • PM10: Particles less than $6 imes 10^{-6}$ meters in diameter.

  • PM2.5: Particles less than $2.5 imes 10^{-6}$ meters in diameter.

• Health Effects:

  • Can cause irritation of the lungs.

  • The smallest particles (PM2.5) can penetrate directly into the bloodstream.

Assessing the Risk of Air Pollutants

• Risk Assessment:

  • Definition: Evaluating scientific data and making organized predictions about the likelihood of adverse occurrences.

• Key Components of Risk:

  • Toxicity: The intrinsic health hazard of a substance.

  • Exposure: The amount of a substance encountered.

• Philosophical Quote:

  • "All things are poison, and nothing is without poison; the dosage alone makes it so a thing is not a poison."

Ambient Air Quality Standards

• Pollutants and Standards:

  • Each pollutant has an established standard in parts per million (ppm) and an approximate equivalent concentration in micrograms per cubic meter (µg/m³).

U.S. Average Levels of Air Pollutants

• Observation: The average concentration of air pollutants in the United States has decreased markedly since 2000.

U.S. EPA’s Air Quality Index (AQI)

• AQI Overview:

  • The Air Quality Index is based on national ambient air quality standards.

• Interpretation of AQI:

  • An AQI of 100 corresponds to the standard concentration for the relevant pollutant.

Air Quality Data for U.S. Metro Areas

• Statistic: It is estimated that over 41% of the U.S. population resides in counties with unhealthy levels of ozone or particulate pollution.

Example of Air Quality Index

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• Variability: Variations in the AQI can reflect changes in local weather patterns.

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• Forecast Data:
  
  

  
  

  Forecast Date	Ozone (O3)	PM10	PM2.5
  Tues 8/21/20	61	61	139
  Wed 8/22/20	90	64	134
  Thurs 8/23/20	112	77	154
  Fri 8/24/20	42	62	114
  Influencing Factors: Regional events such as forest fires and volcanic eruptions can significantly impact air quality.
  Specific Example: Air quality forecast for Spokane, WA from August 21 to 24, 2018 during extensive wildfires in Washington and Northwest Montana.
  Air Quality Index and Regional Events

  • Case Study: From November 8 to November 25, 2018, the Camp Fire in Northern California was recorded as the deadliest wildfire in the U.S. in a century.