For Mumbai pollution, construction dust, unfavourable meteorology obvious culprits but can’t rule out climate change

For Mumbai pollution, construction dust, unfavourable meteorology obvious culprits but can’t rule out climate change

Subject : Environment

Section: Pollution

Context:

• Mumbai has been facing ‘poor’ air quality for the past few days according to the System of Air Quality and Weather Forecasting and Research data (SAFAR).

Details:

• The city’s PM2.5 concentration was about 17 times the safe value recommended by the World Health Organization, according to IQAir, a Swiss air quality information platform.

What is causing the smog in Mumbai?

• In the post-monsoon winter time, a condition of stagnation prevails across India because of boundary layer suppression, the onset of winter and the slowing of wind speeds among others.
• Construction projects in Mumbai and surrounding areas

Smog:

• Smog = smoke + fog (smoky fog) caused by the burning of large amounts of coal, vehicular emission and industrial fumes (Primary pollutants).
• Smog contains soot particulates like smoke, sulphur dioxide, nitrogen dioxide and other components.
• At least two distinct types of smog are recognized: sulfurous smog and photochemical smog.

Types of smog:

• Sulfurous smog (London smog):
  • First formed in London.
  • It results from a high concentration of Sulfur Oxides (SOx) in the air and is caused by the use of sulfur-bearing fossil fuels, particularly coal (Coal was the main source of power in London during the nineteenth century. The effects of coal burning were observed in the early twentieth century).
  • This type of smog is aggravated by dampness and a high concentration of suspended particulate matter in the air.
• Photochemical smog (Los Angeles smog):
  • It occurs most prominently in urban areas that have large numbers of automobiles (Nitrogen oxides are the primary emissions).
  • Photochemical (summer smog) forms when pollutants such as nitrogen oxides (primary pollutant) and organic compounds (primary pollutants) react together in the presence of SUNLIGHT. A gas called OZONE (Secondary pollutant) is formed.
  • Nitrogen Dioxide  +  Sunlight  +  Hydrocarbons  =  Ground-level Ozone
  • The resulting smog causes a light brownish colouration of the atmosphere, reduced visibility, plant damage, irritation of the eyes, and respiratory distress.
• Haze:
  • Haze is traditionally an atmospheric phenomenon where dust, smoke and other dry particles obscure the clarity of the sky (No condensation. Smog is similar to haze but there is condensation in smog).
  • Sources for haze particles include farming (ploughing in dry weather), traffic, industry, and wildfires.

Source of this article: Down to Earth