Levels of Ozone Exceeding Permitted Limits

Levels of Ozone Exceeding Permitted Limits


A recent study by the Centre for Science and Environment (CSE) discovered that ozone levels in Delhi-NCR surpass the permissible threshold even during the winter, making the smog more “hazardous.”

Despite the epidemic and lockdowns, ozone spells were higher and lasted longer on more days and in more regions.

CSE is a New Delhi-based public interest research and advocacy organisation.



  • Ozone (a gas made up of three oxygen atoms) is found in both the upper and lower atmospheres of the Earth. Depending on where it is in the atmosphere, ozone can be “good” or “bad” for human health and the environment.

  • The ‘good’ ozone in the earth’s stratospheric layer protects humans from damaging Ultraviolet (UV) radiation, but ground-level ozone is extremely reactive and can have negative health effects.

  • Ozone at ground level is harmful to people with asthma and other respiratory problems.


  • Smog is a type of air pollution that limits vision, and the name “smog” was initially used to describe a mixture of smoke and fog in the early 1900s.

  • The smoke was mainly caused by coal burning. Smog is widespread in industrial regions and is still seen today in cities. Photochemical smog is created when sunlight combines with nitrogen oxides (NOx) and at least one volatile organic compound (VOC) in the atmosphere, which accounts for the majority of the smog we see today.

  • Nitrogen oxides are emitted by automobiles, coal-fired power plants, and factories. Gasoline, paints, and a variety of cleaning solvents all emit VOCs. When these compounds are exposed to sunlight, they produce airborne particles and ground-level ozone, sometimes known as smog.

The following are some of the study’s main points:

It’s Now a Year-Round Threat:

  • Contrary to popular belief, Ozone is not only a summer problem; it has also been discovered that gas is a serious problem in the winter.

Exceedance on Occasion:

  • The city-wide average largely adheres to the standard, with just minor deviations. However, in Delhi, the ‘good’ category days have decreased to 115 days in 2020, which is 24 days less than in 2019.

  • A location-by-location analysis reveals that exceeding the eight-hour average requirement is rather common in the metropolis.

  • Even smaller NCR towns, such as Bulandshahr in Uttar Pradesh and Bhiwani in Haryana, made the top 20 list of ozone-affected cities. The list is dominated by sites in South Delhi, with four mentions in the top ten.

Suggestions made in the research:

  • The study found that the transportation sector is the largest source of NOx and VOCs, implying that considerable action is required against these high emitters of NOx and VOCs, such as automobiles and other businesses.

  • Ozone levels have been found to exceed 100 g/m3 even in the winter, and they are extremely sensitive to sun radiation. By reducing the gases, secondary particles generated by these gases will be reduced as well.

  • Ozone is becoming a year-round, urgent concern, and the circumstance necessitates the refining of a clean air action plan to include ozone mitigation methods, as well as tougher action on automobiles, industry, and trash burning.

  • It’s critical to calibrate the AQI (Air Quality Index) to report the day’s most polluted eight-hour average, ideally on an hourly basis. In addition, the existing practice of merely averaging cities has to be changed to include notifications based on the worst-affected area, as is standard practice around the world.

Efforts by the government:

  • Under the auspices of the Central Pollution Control Board, the National AQI for public information is being developed (CPCB). PM2.5, PM10, Ammonia, Lead, nitrogen oxides, sulphur dioxide, ozone, and carbon monoxide are the eight pollutants for which an AQI has been established.

  • To reduce vehicular pollution, BS-VI vehicles will be introduced, as well as a push for electric vehicles (EVs), Odd-Even as an emergency solution, and the development of the Eastern and Western Peripheral Expressways.

  • Implementation of the Graded Response Action Plan (GRAP) to address the Capital’s growing pollution. It includes measures such as the shutdown of thermal power plants and a construction moratorium.

  • The National Clean Air Program (NCAP) was launched: The government created the National Clean Air Programme (NCAP) to address air pollution on a national level in a comprehensive manner, with the goal of meeting average ambient air quality criteria in all parts of the country.

    Source: The Hindu

    Syllabus: Environment (GS 3)


Download Yojna IAS Daily Current Affairs of 3rd August 2021

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