Consider the following statements regarding mercury pollution. How many of the above statements are correct?


05:23 AM

UPSC Prelims 2023 Question:

Consider the following statements regarding mercury pollution:

  1. Gold mining activity is a source of mercury pollution in the world.
  2. Coal-based thermal power plants cause mercury pollution.
  3. There is no known safe level of exposure to mercury.

How many of the above statements are correct?

a) Only one

b) Only two

c) All three

d) None

Correct Answer: Option b) Only two


  • Mercury (Hg) is a global pollutant that affects human and ecosystem health. We synthesize understanding of sources, atmosphere-land-ocean Hg dynamics and health effects, and consider the implications of Hg-control policies. Primary anthropogenic Hg emissions greatly exceed natural geogenic sources, resulting in increases in Hg reservoirs and subsequent secondary Hg emissions that facilitate its global distribution. The ultimate fate of emitted Hg is primarily recalcitrant soil pools and deep ocean waters and sediments.

Mercury Pollution

  • One major source of mercury emissions is small-scale gold mining that occurs in many countries. Artisanal gold mining currently contributes more than 35 per cent of all global mercury emissions created by people. So, statement 1 is correct.
  • Coal-based thermal power plants are a known source of mercury pollution. When coal is burned to generate electricity, trace amounts of mercury present in coal can be released into the atmosphere as emissions. These emissions contribute to mercury pollution. So, statement 2 is correct.
  • According to the Occupational Safety and Health Administration (OSHA), mercury vapor concentrations greater than 0.01 mg/m³ are considered unsafe for prolonged exposure. OSHA sets the permissible exposure limit (PEL) for mercury vapor at 0.1 mg/m³ as an 8-hour time-weighted average. The National Institute for Occupational Safety and Health (NIOSH) and the American Conference of Governmental Industrial Hygienists (ACGIH) recommend even lower exposure levels to minimize health risks. So, statement 3 is not correct.

Therefore, option (b) is the correct answer.

Subject: Environment | Pollution

Tags: Conceptual