Why in News?

  • According to a forecast by the System of Air Quality and Weather Forecasting and Research (SAFAR), with rising temperatures, surface ozone pollution is expected to increase in Delhi in the next three days.


  • Ozone, a key component of photochemical smog, is formed by a complex reaction between nitrogen dioxide and hydrocarbons in the presence of sunlight.
  • Ozone is considered to be a criteria pollutant in the troposphere — the lowermost layer of the atmosphere — but not in the upper atmosphere, where it occurs naturally and serves to block harmful ultraviolet rays from the Sun.
  • When temperature increases, the rate of production of surface ozone also increases.
  • Surface Ozone can lead to cough, shortness of breath, throat pain in the short term and cause corrosion of linings of lungs and make lungs vulnerable to further infections in case of long-term exposure.
  • Photochemical smog is produced when pollutants from the combustion of fossil fuels react with sunlight. The energy in the sunlight converts the pollutants into other toxic chemicals. In order for photochemical smog to form, there must be other pollutants in the air, specifically nitrous oxides and other volatile organic compounds (VOCs).
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