Ringelmann's Scale is Used to

By Aina Parasher|Updated : July 7th, 2022

Ringelmann's scale is used to- 

  1. Measure CO
  2. Measure SO2
  3. Grade density of smoke
  4. Grade automobile exhaust gas

Answer: C. Grade density of smoke

Ringelmann's scale is used to grade density of smoke.


The Ringelmann scale is a scale used for the determination of the apparent density or opacity of Smoke.

  • French professor of agricultural engineering Maximilien Ringelmann of La Station d'Essais de Machines first developed the Ringelmann scale in Paris in 1888.
  • The scale has 5 levels of density implied from a grid of black lines on a white surface which merge into known shades of grey if viewed from a distance.
  • Shade 1 is slightly grey and is classified by air pollution boards as acceptable. It resembles to an opacity of 20%.
  • Shades 2, 3, 4 and 5 resemble to opacities of 40%, 60%, 80% and 100% i.e. completely black and are treated to be "black smoke" by air pollution boards of most of the countries.

Hence, the correct option is C.

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