Environmental pollution caused by dust particles

There are many sources of dust particles (particulate matter (PM)) in the atmosphere, which we commonly refer to as dust.

• Chemical reactions of atmospheric gases

Chemical reactions of atmospheric gases lead to the production of small particles of a few nanometers in diameter (1 nanometer is one millionth of a meter), which grow relatively quickly by condensation.

There are multiple pathways of formation.Sulfates are formed from atmospheric reactions of sulfur dioxide (SO2), which comes from anthropogenic or volcanic releases, or from natural oceanic emissions of dimethyl sulfide (DMS).

• • Nitrates are formed by the oxidation of nitrogen dioxide (NO2), which itself is mainly derived from nitric acid formed by the oxidation of nitric oxide (NO) released during the combustion of fossil fuels, which can then react to form nitrates.
  • Ammonium-containing aerosols are produced by the reaction of ammonia (NH3) emissions with acidic gases.
  • Organic aerosols are produced by the gas-phase oxidation of non-methane volatile organic compounds (NMVOC) from anthropogenic and natural emissions, usually by oxidation processes in the presence of sunlight.

• Combustion processes of substances

For example, in industrial and transport combustion, these actions result in direct emissions of fine particles, typically in the size range of 0.1 – 2.5 µm diameter (1 µm is one millionth of a meter).

• • Carbon containing particles (soot) are emitted by industry and vehicles when burning carbon-based fuels (coal, oil, natural gas)
  • Particles containing heavy metals are emitted from various industrial and transportation sources. Particulate emissions from cities currently far exceed those from rural areas, but there is little data to quantify the risk of particulate emissions from urban areas.

• Mechanical generation

This generates coarse particles (2.5 – 20 µm) laid out by wind turbulence.

• • From sources of friction of metal particles, such as tire and brake wear.
  • Agricultural soil erosion, volcanic eruptions, mining, etc. can emit particulate matter containing minerals.
  • Cement and fertilizer dust comes from factories and construction sites – and may also be emitted directly.
  • Sea salt particles are produced by bubbles in the ocean or coastal areas Chemical reactions of acidic SO 2 and NO x with alkaline NH 3 can also occur on the surface of existing particulate matter.

These reactions chemically lead to a large mixing between the different pollutants contained in the particles.

Therefore, after surviving in the atmosphere for many days, individual particles may contain both water-soluble components (e.g., sulfates, nitrates, and ammonium) and insoluble components (e.g., carbon, heavy metals, or soil).

The rate of removal from the atmospheric air depends on the size of the particulate matter. Large particles are deposited rapidly near their sources due to gravity, small particles are deposited relatively quickly due to movement, and particles in the medium size range (0.1 – 2 µm) are deposited slowly, moving at long intervals between countries and continents.

• Impacts and problems caused

December 5th to 7th, 1952, London, England because of the coal smog event death toll of more than four thousand people, after people called this catastrophic smog “killer smog”. According to the analysis, this is because those days of London Wufeng fog, factory chimneys and residential heating emissions do not disperse for a long time, soot concentration is too large, the generation of sulfuric acid concentrated liquid attached to the dust is inhaled by people, so that people develop or accelerate the death of chronic disease patients.

Because of the relatively large number of pollutants and chemical components involved, dust particles have a large impact in many environmental pollution problems. For example:

• • particles are concerned with human health; respiratory and heart problems caused by inhaling small particles are related to the mass concentration of particles less than 10 microns in diameter.
  • Excessive plant cover dust affects plant growth, destroys plant physiology and causes a decrease in plant yield.
  • Soil acidification and eutrophication caused by regional pollutant deposition  .
  • Deposition of heavy metals with toxic effects has significant impact on plant, animal and human health.
  • Transboundary transport of air pollutants as fine particulate matter.
  • Increased atmospheric temperature: In large industrial cities, the air temperature near the ground is much higher than the surrounding areas due to dust particles and other emissions, creating a “heat island effect”.
  • The impact that climate change will have on PM concentrations in polluted environments in the coming decades. Wildfires triggered by climate change are likely to become an increasingly important source of PM
  • 8There are many small particles in the haze, and light scattering leads to reduced visibility.

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