Unit-iv unit-iv environmental Hygiene


Coal dust explosion (China, 1942 and Chasnala, India, 1957)



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Atmospheric-pollution

Coal dust explosion (China, 1942 and Chasnala, India, 1957)

    • Coal dust explosion (China, 1942 and Chasnala, India, 1957)
    • Forest fires (South East Asia, 1997-98): impact on health & productivity
  • Nitrogen oxide & hydrocarbons present in the atmosphere (following use of petrol by the automobiles) reacted with sunlight
  • Toxic compounds were produced through a photochemical reaction between sunlight & the two pollutants
  • The photochemical smog pollution of 1969 has been reported in detail as a part of episode 104 (associated with hurricane Camille emanating from Gulf of Mexico)

Air pollution: a historical perspective

Classification of air pollutants

A wide variety of pollutants are present in the atmosphere

In order to understand their impact on health & ecology, & to evolve appropriate strategies for their control, the pollutants are classified in a number of ways:

  • Source of emission,
  • Physico-chemical characteristics &
  • Effects on life processes

Sources of air pollutants


Natural sources
Man induced activities
  • Geochemical contamination,
  • Photochemical reactions,
  • Change in climatic conditions,
  • Volcanic eruptions,
  • Gaseous discharge from marshes & swamps,
  • Forest fires
  • Dust, fog & radiation fall-outs
  • Microbial agents

Sources
  • Incineration: wood, coal, petroleum products,
  • Automobile industry: oxides of sulphur & nitrogen, carbon monoxide, smoke & fly ash
  • Oil refineries
  • Iron/steel mills, fertilizer plants & rendering units metal fumes & fluorides into the atmosphere
  • Agricultural, textile, paper & pharmaceutical industries
  • Dust particles: milling, crushing /grinding
  • pesticide & drug residues
  • Organic/inorganic vapours

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