Aerosol Pollution

Aerosol Pollution

Subject: Environment

Section: Pollution

Context- Scientists say that accurately modelling the intensity of aerosol effects on climate change is vital to humanity’s future but aerosol complexity makes it difficult to model and understand. 

Concept-

• Aerosols are fine particulates that float in the atmosphere.
• While there has not been significant change in presence of natural aerosols, human-caused aerosols have increased rapidly.
• An immense aerosol cloud regularly swirls over India, China and Southeast Asia, fed by particles of ash, soot and organic carbon compounds.

About Aerosols:

• Aerosols are a mixed bag of substances, liquid and solid, that differ from their gassy brethren.
• They tend to hang in the atmosphere near their source, or move as localised or regional masses via air currents.
• They range in size from a few atoms across to the width of a human hair.
• They include:
  • crystals of sulphate,
  • balls of almost pure black carbon (commonly, though not entirely accurately, called soot),
  • droplets of nitric or sulfuric acid, spores of pollen.
• They may be salt freed from the crests of breaking waves, or desert sand whipped up by the wind.
• Natural Aerosols: One of the largest natural sources of aerosols are plankton, which breathe out dimethyl sulphide (DMS), a strong-smelling chemical that gives the sea it’s familiar pungent odour.
  • DMS reacts with oxygen to produce clouds of sulfuric acid.
  • Sulphur dioxide released by volcanoes does the same.
• Ninety percent of aerosols in the atmosphere are naturally occurring, but their levels have remained relatively constant over time.
• Anthropogenic Aerosols: On the other hand anthropogenic, or human-made aerosols are emitted from:
  • vehicle exhausts;
  • the smokestacks of factories,
  • ships and coal-burning powerplants;
  • by farmers burning field stubble and land grabbers clearing Amazon forest with fire;
  • by gas flares on oil rigs and discarded plastic shopping bags.
  • Even tumble driers release microplastic fibres that float skyward.
• These sources have increased dramatically over the industrial period, roughly in step with greenhouse gases.
• Most aerosols help cool the planet by reflecting sunlight back out into space, reducing the amount of radiant energy that reaches Earth’s surface.
• They also help create clouds or brighten existing clouds, by acting as condensation nuclei around which water vapor condenses.
• Aerosols first came to public attention in the 1970s, not so much because of their cooling impact, but due to acid rain.
• The worst aerosols are very fine particulates that can penetrate deep into the lungs and may even enter the blood stream exacerbating respiratory and cardiovascular conditions.