Air Pollution: Health Effects, Smog, and Biomonitoring

Posted on Sep 4, 2024 in Biology

Hazard Effects of Common Chemical Pollutants in the Open Air

Photooxidative and Reductive Smog, Formation, and Health Risks; Biomonitoring of Atmospheric Pollution

Background:

  • Air pollution is the introduction of chemicals, particulate matter, or biological materials that cause harm or discomfort to humans or other living organisms, or cause damage to the natural environment or built environment, into the atmosphere.

  • A substance in the air that can cause harm to humans and the environment is known as an air pollutant.

  • Pollutants can be in the form of solid particles, liquid droplets, or gases.

Moreover, they may be natural or man-made.

Chemical Pollutants:

Primary Pollutants (Directly Emitted):

Examples: Ash from volcanic eruption, CO gas from motor vehicle exhaust, or sulfur dioxide released from factories.

  • Sulfur and nitrogen oxides
  • Carbon monoxide – from incomplete combustion (odorless, colorless)
  • Carbon dioxide
  • Volatile organic compounds
  • Toxic metals
  • Persistent free radicals
  • Odors
  • Radioactive pollutants
  • Particulate matter (dust, ash, salt particles)
Secondary Pollutants (Formed in the Air):

Examples: Ground-level ozone, sulfuric acid, nitrogen dioxide.

Mixed Pollutants (Both Primary and Secondary):

Sources of Pollutants:

Anthropogenic Sources (Human Activity):

Examples: Stationary (power plants), mobile (motor vehicles), chemicals and dust, fumes (paint, hairspray, varnish, aerosol sprays), waste deposition in landfills that generate methane, military (nuclear weapons, toxic gases).

Natural Sources:

Examples: Dust, methane (from digestion of food by animals), radiation (from Earth’s crust), smoke and CO from wildfires, volcanic activity (sulfur, chlorine).

Health Effects:

  • Air pollution is a significant risk factor for several health conditions, including respiratory infections, heart disease, COPD, stroke, and lung cancer.

  • Short-term effects: Irritation to the eyes, nose, and throat, LRTI (bronchitis, pneumonia), headaches, nausea, allergic reactions, and aggravation of medical conditions such as asthma and emphysema.

  • Long-term effects: Chronic respiratory disease, lung cancer, heart disease, damage to the brain, nerves, liver, or kidneys; children may experience impaired lung development, and the elderly may show aggravation of medical conditions.

Specific Health Effects:

Particulate matter: Cardiovascular and respiratory diseases, lung cancer.

Ozone (O3): Breathing problems, triggers asthma, reduces lung function, lung diseases.

Nitrogen dioxide (NO2): Bronchitis, reduced lung function growth.

CO: Impaired night vision, reduced mental acuity, impaired motor skills.

Smog: A Type of Air Pollutant

The word “smog” was coined in the early 20th century by combining the words smoke and fog.

Types of Smog:

  • Reductive Smog (London-type): From coal smoke combining with water vapor and liquid water in cool, humid, or foggy air.

  • Photochemical Smog (LA-type, Modern Smog): Pollution derived from vehicular emissions from internal combustion engines and industrial fumes that react in the atmosphere with sunlight to form secondary pollutants. These secondary pollutants combine with the primary emissions to form photochemical smog. More common in cities with sunny, warm, dry climates and a large number of vehicles. Because it travels with the wind, it can affect sparsely populated areas as well.

Health Effects of Smog:

  • Smog is a serious problem in many cities and continues to harm human health.

  • Ground-level ozone, sulfur dioxide, nitrogen dioxide, and carbon monoxide are especially harmful to senior citizens, children, and people with heart and lung conditions such as emphysema, bronchitis, and asthma.

  • It can inflame breathing passages, decrease the lungs’ working capacity, cause shortness of breath, pain when inhaling deeply, wheezing, and coughing.

  • It can also cause eye and nose irritation and dries out the protective membranes of the nose and throat, interfering with the body’s ability to fight infection, increasing susceptibility to illness.

  • Hospital admissions and respiratory deaths often increase during periods when ozone levels are high.

Biomonitoring:

Biomonitoring is the measurement of the body burden of toxic chemical compounds, elements, or their metabolites in biological substances. This may contribute to improving risk assessments.

  • These measurements are typically done in blood and urine (and sometimes hair).

  • A single biomonitoring measurement is only one snapshot in time and may not accurately reflect the level of exposure over longer periods.