Exceeding Ozone Levels

In News

Recently, a Centre for Science and Environment (CSE) study has found that ozone levels are exceeding the permitted levels even during winter in Delhi-NCR, making the smog more “toxic”.

About the Issue

• Ozone is now a round-the-year problem requiring urgent action.
• The situation demands refinement of a clean air action plan to add strategies for ozone mitigation, with stronger action on vehicles, industry and waste burning.
• Ozone, a highly reactive gas and dangerous for those suffering from respiratory conditions and asthma, is becoming more widespread in Delhi and NCR across all seasons

Ozone

• Formula: Ozone, or trioxygen, is an inorganic molecule with the chemical formula O?.
• Feature: It is a pale blue gas with a distinctively pungent smell.
• Good and Bad Ozone
  • Stratospheric ozone (Good Ozone) is formed naturally through the interaction of solar ultraviolet (UV) radiation with molecular oxygen (O2).  The “ozone layer,” approximately 6 through 30 miles above the Earth’s surface, reduces the amount of harmful UV radiation reaching the Earth’s surface.
  • Tropospheric or ground-level ozone (Bad Ozone), what humans breathe, is formed primarily from photochemical reactions between two major classes of air pollutants, volatile organic compounds (VOC) and nitrogen oxides (NOx). 
  • These reactions have traditionally been viewed as depending upon the presence of heat and sunlight, resulting in higher ambient ozone concentrations in summer months. 
  • Although some stratospheric ozone is transported into the troposphere and some VOC and NOx occur naturally, the majority of ground-level ozone is the result of reactions of man-made VOC and NOx.
• Anthropogenic Sources
  • Significant sources of VOC are: chemical plants, gasoline pumps, oil-based paints, auto body shops, print shops.
  • Nitrogen oxides result primarily from high temperature combustion, power plants, industrial furnaces and boilers and motor vehicles.
• Ozone Hole
  • Ozone depletion is greatest at the South Pole.
  • It occurs mainly in late winter and early spring (August-November) and peak depletion usually occurs in early October, when ozone is often completely destroyed in large areas.
  • This severe depletion creates the so-called “ozone hole” that can be seen in images of Antarctic ozone, made using satellite observations.
  • In most years, the maximum area of the hole is bigger than the Antarctic continent itself.
  • Although ozone losses are less radical in the Northern Hemisphere, significant thinning of the ozone layer is also observed over the Arctic and even over continental Europe.
  • Most of the ozone-depleting substances emitted by human activities remain in the stratosphere for decades, meaning that ozone layer recovery is a very slow, long process.
• Recent Developments
  • Within the last decade, however, high ozone concentrations have also been observed under specific circumstances in cold months, where a few high elevation areas in the Western US with high levels of local VOC and NOx emissions have formed ozone when snow is on the ground and temperatures are near or below freezing.
  • Ozone contributes to what we typically experience as “smog” or haze, which still occurs most frequently in the summertime but can occur throughout the year in some southern and mountain regions.

International Treaties and Cooperation about the Protection of the Stratospheric Ozone Layer

• Origin
  • Through the 1970s and the 1980s, the international community became increasingly concerned that ODS would harm the ozone layer.
  • In 1985, the Vienna Convention for the Protection of the Ozone Layer formalized international cooperation on this issue.
  • This cooperation resulted in the signing of the Montreal Protocol on Substances that Deplete the Ozone Layer in 1987.
  • Because of measures taken under the Montreal Protocol, emissions of ODS are falling and the ozone layer is expected to be fully healed near the middle of the 21st century.
• Montreal Protocol on Substances that Deplete the Ozone Layer
  • The original Montreal Protocol, signed in 1987, was the first step in international efforts to protect stratospheric ozone.
  • Under the original Montreal Protocol agreement (1987), developed countries were required to begin phasing out CFCs in 1993 and achieve a 20% reduction relative to 1986 consumption levels by 1994 and a 50% reduction by 1998.
  • Additionally, developed countries were required to freeze their production and consumption of halons relative to their 1986 levels.
  • After the Montreal Protocol was signed, new data showed worse-than-expected damage to the ozone layer.
• Amendments to the Montreal Protocol
  • The London Amendment (1990) changed the ODS emission schedule by requiring the complete phaseout of CFCs, halons, and carbon tetrachloride by 2000 in developed countries, and by 2010 in developing countries. Methyl chloroform was also added to the list of controlled ODSs, with phaseout in developed countries targeted in 2005, and in 2015 for developing countries.
  • The Copenhagen Amendment (1992) significantly accelerated the phaseout of ODSs and incorporated a hydrochlorofluorocarbons (HCFC) phaseout for developed countries, beginning in 2004. Under this agreement, CFCs, halons, carbon tetrachloride, and methyl chloroform were targeted for complete phaseout in 1996 in developed countries. In addition, consumption of methyl bromide was capped at 1991 levels.
  • The Montreal Amendment (1997) included the phaseout of HCFCs in developing countries, as well as the phaseout of methyl bromide in developed and developing countries in 2005 and 2015, respectively.
  • The Beijing Amendment (1999) included tightened controls on the production and trade of HCFCs. Bromochloromethane was also added to the list of controlled substances with phaseout targeted for 2004.
  • The Kigali Amendment (2016) extended controls to phase down the production and consumption of hydrofluorocarbons (HFCs) because these substances were adopted by industries in moving away from ozone-depleting substances and they are potent greenhouse gases damaging to the earth’s climate.
• The Vienna Convention
  • Adopted in 1985, The Vienna Convention for the Protection of the Ozone Layer is the precursor to the Montreal Protocol.
  • It is often called a framework convention, because it served as a framework for efforts to protect the globe’s ozone layer.
  • The Vienna Convention did not require countries to take concrete actions to control ozone depleting substances.
  • Instead, in accordance with the provisions of the Convention, the countries of the world agreed the Montreal Protocol on Substances that Deplete the Ozone Layer under the Convention, to advance that goal.
• United Nations Environment Programme (UNEP) Ozone Secretariat
  • U.S. agencies, including EPA, work with the UNEP Ozone Secretariat to implement the Montreal Protocol.
• Assessment Panels
  • The Parties the Montreal Protocol have advisory bodies called Assessment Panels. The Assessment Panels are responsible for issuing regular reports on progress on implementing the phaseout of ozone-depleting substances, including assessments of alternatives and emissions reduction.
• TEAP – The Technology and Economic Assessment Panel (TEAP)
  • It provides technical information related to the alternative technologies that have been investigated and employed to make it possible to virtually eliminate use of Ozone Depleting Substances (such as CFCs and Halons), that harm the ozone layer.
• OzonAction
  • UNEP’s Division of Technology, Industry, and Economics OzonAction Programme provides industry, government, and other stakeholders in developing countries with information exchange services, training, and networking. In addition to these core clearinghouse services, the Programme also provides assistance with Country Programmes and Institutional Strengthening projects.

Way Forward

• Ensuring that existing restrictions on ozone-depleting substances are properly implemented and global use of ozone-depleting substances continue to be reduced.
• Ensuring that banks of ozone-depleting substances (both in storage and contained in existing equipment) are dealt with in an environmentally-friendly manner and are replaced with climate-friendly alternatives.
• Ensuring that permitted uses of ozone-depleting substances are not diverted to illegal uses.
• Reducing use of ozone-depleting substances in applications that are not considered as consumption under the Montreal Protocol.
• Ensuring that no new chemicals or technologies emerge that could pose new threats to the ozone layer (e.g. very short-lived substances).

Source: TH