Air Pollution: Characteristics, Effects, and Solutions

Posted on Sep 30, 2024 in Geology

Characteristics of Issues

The nature, concentration, and physicochemical properties of a contaminant determine its impact. When a gas’s temperature exceeds the surrounding medium’s, it rises, facilitating dispersion. Higher altitudes increase the chance of bypassing thermal inversion layers, further aiding dispersion.

Atmospheric Conditions

Air temperature and its variation with height: These factors influence air mass movement and atmospheric stability. Temperature variations can lead to thermal inversions, hindering contaminant dispersion.

Winds: Wind direction indicates potential pollutant movement. Wind speed directly relates to dispersion capacity: higher speeds mean greater dispersion. Turbulence can cause pollutant accumulation.

Rainfall: Rainfall washes the atmosphere, carrying some pollutants to the ground.

Sunlight: Sunlight promotes reactions between secondary pollutant precursors, increasing their concentration.

Geographical and Topographical Features

Location and relief influence contaminant origins, accumulation, or washout.

  • Coastal areas: Daytime breezes move pollutants inland, while nighttime breezes move them towards the sea.
  • River valleys and foothills: Valley and mountain breezes arise from differential heating of slopes and valleys during day-night cycles. Daytime heating of slopes generates ascending hot air currents, while cold air accumulates in valleys, creating thermal inversions that hinder dispersion.
  • Vegetation: Vegetation reduces air pollution by slowing wind speed and absorbing CO2 for photosynthesis, acting as a sink and regulator.
  • Urban centers: Urban areas affect air mass movement, decreasing speed and creating turbulence. The urban heat island effect raises city temperatures compared to surrounding areas due to combustion in vehicles. This favors urban breezes, hindering pollutant dispersion and forming the characteristic “urban pollutant dome.”

Effects of Air Pollution

Air pollution negatively impacts living organisms, materials, and ecosystems, with short-term (e.g., human health) and long-term (e.g., climate change) effects. Effects can be local, regional, or global. Pollutant type, concentration, and exposure time influence the degree and type of effects.

Local Effects

Smog: Smog formation results from the interaction between atmospheric conditions and air pollution. Two types exist:

  • Caustic or wet smog: Originates from high concentrations of suspended particles, SO2, and gray mist from vehicles. It causes respiratory problems and worsens asthma.
  • Photochemical smog: Results from photochemical reactions in the atmosphere involving nitrogen oxides, hydrocarbons, oxygen, and solar ultraviolet radiation. It is favored by anticyclones, strong sun, and weak winds. These reactions include ozone formation from NO2 photolysis, active free radical formation from hydrocarbon radicals, and PAN formation.

Transboundary Pollution

Pollutants can return to earth in areas near and far from emission sources.

Regional Effects: Acid Rain

Acid rain is the return of sulfur and nitrogen oxides emitted into the atmosphere, dissolved as acids in rain, snow, or fog. It begins when sulfur and nitrogen from fossil fuels are released during combustion, react, precipitate, and return to the surface in two ways:

  • Dry deposition: Gases and aerosols deposit near emission sources.
  • Wet deposition: Atmospheric SO2 and NOX oxidize to form H2SO4 and HNO3, which dissolve in cloud water droplets and are transported back to the ground by rain.

Acid rain intensity depends on: Chemical reaction rates, atmospheric moisture, and atmospheric dynamics.

Effects of acid rain:

  • Aquatic ecosystems: Increased acidity harms aquatic life.
  • Soil: Increased acidity alters soil composition.
  • Vegetation: Damage to leaves and other plant parts.
  • Materials: Corrosion and deterioration of various materials.

Air Quality

Monitoring Air Quality

Air quality monitoring involves systems and procedures to assess atmospheric pollutants, their concentrations, and their spatial and temporal variations to prevent and reduce environmental and health impacts. This is done through surveillance networks (local, community, or global), analysis methods (physical or chemical), biological indicators, and sensors.

Measures for Prevention and Correction

Prevention: Land use planning, environmental impact assessments, low- or no-waste emission technologies, R&D programs, improved fuel quality, social information measures, and legislation.

Correction: Particle retention, gas purification systems, and pollutant removal.

Noise Pollution

Noise is excessive sound that can cause unwanted physiological and psychological effects on people.

Origins and Sources of Noise

  • Industry (machinery)
  • Construction
  • Transportation
  • Public spaces and buildings
  • Other sources (leisure, free time, etc.)

Effects of Noise

Factors influencing noise effects include exposure time, age, lifestyle, and work. Effects include physiological abnormalities (hearing loss, respiratory, circulatory, digestive, and endocrine system issues) and psychological disorders (neurosis, irritability, stress). Intensity, source, pitch, and individual sensitivity are key factors.

Solutions to Noise Pollution

Precautionary Measures

  • Land use planning and urban architecture
  • Environmental impact studies
  • Fines and fees
  • Noise reduction systems at the source
  • Information and environmental education

Corrective Actions

Limit and reduce noise at its source and protect the most exposed populations. These include regulations and direct action on emission sources.