Coronavirus lockdown: Air pollution in India lowest in 20 years, says NASA

22 April 2020

Aerosol levels plummet drastically in April 2020!


At present Air pollution in India is at its lowest in two decades, says a study published by US space agency National Aeronautics and Space Administration (NASA).

Highlights of the Study:

  • Study was conducted by   Pawan Gupta of Universities Space Research Association’s(USRA’s) along with NASA team at Marshall Space Flight Centre.
  • The study reveals an all time low aerosol levels in Northern India and over the Indo-Gangetic plains.
  • This is due to the low anthropogenic activities because of the lockdown prevailing in the wake of COVID-19.
  • Normally during this time of the year there is a rise in the aerosol levels due to increased human activities- motor vehicles, coal fed power plants, industrial sources around urban areas producing sulphates, nitrates, coal combustion producing soot and other carbon rich particles.
  • Rural areas add smoke rich in black carbon and organic carbon from cooking and heating.

What are aerosols?

  • Aerosols are tiny solid and liquid particles suspended in the air that reduce visibility and can damage human lungs and heart.
  • Some aerosols arise from natural sources like dust storms, volcanic eruptions and forest fires. Others come from human activities such as burning of fossil fuels and crop lands.
  • Man made aerosols tend to contribute most of the smaller particles that have greater penetration for damaging human health.

What is Aerosol Optical Depth?

  • Aerosol optical depth is a measure of how light is absorbed or reflected by airborne particles as it travels through the atmosphere.
  • If aerosols are concentrated near the surface at an optical depth of 1 or above –this indicates very hazy conditions.
  • An optical depth of less than 0.1 over the entire atmospheric vertical column is considered “clean’’.
  • The AOD (aerosol optical depth) patterns were studied by MODIS model. MODIS- Moderate Resolution Imaging Spectroradiometer.
  • A comparative study  of aerosols  in the Northern part of India over the years from 2016 is depicted in the self- explanatory pictures above.

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