The Ozone Layer and India’s Role Explained

The ozone layer is a thin band of ozone gas in the stratosphere, roughly 15 to 35 kilometres above the ground, that absorbs most of the sun’s harmful ultraviolet radiation and so shields life on Earth, including everyone in India. It is one of the great environmental repair stories: after chemicals such as CFCs were found to be eating away at it, the world agreed to phase them out, and India has been a full participant in that effort.

This explainer separates the protective ozone high above us from the harmful ozone near the ground, explains how the Antarctic hole formed, and traces India’s role through the Montreal Protocol, the HCFC phase-out, the Kigali Amendment on HFCs and the India Cooling Action Plan. Last updated: 3 November 2026. Figures are kept qualitative or rounded, and timelines for recovery are model projections rather than certainties.

Key Takeaways

• The ozone layer in the stratosphere blocks most harmful ultraviolet radiation, protecting human skin and eyes, crops, plankton and ecosystems.
• Chlorine and bromine released from man-made chemicals such as CFCs destroy ozone, which created the seasonal Antarctic ozone hole.
• The Montreal Protocol is widely regarded as the most successful environmental treaty, and the layer is projected to recover gradually through this century.
• India joined the treaty in 1992, received international funding to help industry change over, and phased out CFCs and other major ozone-depleting chemicals by 2010.
• India is now phasing down HCFCs and, under the Kigali Amendment, HFCs, which do not harm ozone but are powerful greenhouse gases.
• Ground-level ozone is a different thing: it is a pollutant that harms health and crops, and it is not fixed by the Montreal Protocol.

What is the ozone layer?

The ozone layer is a region of the stratosphere where the concentration of ozone, a molecule made of three oxygen atoms, is much higher than elsewhere in the atmosphere. Even there, ozone is a trace gas, and if all of it were gathered into one layer at normal surface pressure it would be only a few millimetres thick. Its importance is far out of proportion to its quantity.

Ozone forms naturally when ultraviolet light splits ordinary oxygen molecules in the stratosphere, and the freed atoms attach to other oxygen molecules. It is also constantly destroyed and renewed, so the layer is a balance rather than a fixed shell. Ozone is thicker over higher latitudes and thinner over the tropics, which is why India naturally has a thinner ozone column than Europe, even though India has not seen anything like the Antarctic hole. Scientists measure the amount of ozone in Dobson units, with a typical global average of roughly three hundred units.

Why does the ozone layer matter for India?

The ozone layer matters for India because the country lies close to the equator, where the sun is high and ultraviolet radiation is already strong, so any thinning would raise exposure from a high base. Ozone absorbs the most damaging UV-C and much of the UV-B, and the radiation that reaches the ground can cause sunburn, skin cancers, cataracts and weakened immune responses in people, and can damage crop leaves, phytoplankton and the early life stages of fish and amphibians.

For a country with a huge outdoor workforce, including farmers, construction workers, fishers and street vendors, the stakes are considerable. India’s coastal waters support large fisheries that depend on phytoplankton at the bottom of the food web, and many staple crops, including some rice and wheat varieties, show sensitivity to heavy UV-B in experiments. These effects were why the world acted early. The UV Index forecasts now provided by weather agencies are a daily reminder that protection of the ozone layer and personal sun protection go hand in hand.

What caused the ozone hole?

The ozone hole was caused by man-made chemicals, chiefly chlorofluorocarbons or CFCs, which carry chlorine and bromine into the stratosphere where they destroy ozone in a catalytic chain reaction. CFCs were once prized as safe and stable chemicals for refrigerators, air conditioners, aerosol sprays and foam, and their stability is exactly why they drift up to the stratosphere intact. There, intense ultraviolet light breaks them apart, releasing chlorine atoms that can each destroy many thousands of ozone molecules.

The hole appears over Antarctica each spring in the southern hemisphere, from roughly August to October, because extremely cold winter stratospheric clouds provide surfaces on which chlorine is converted into reactive forms, and returning sunlight then triggers rapid ozone destruction. The hole is not a literal opening but a region of severely depleted ozone, officially defined as a column dropping below about 220 Dobson units. The British Antarctic Survey scientists who reported it in 1985, and the chemists Molina and Rowland who had warned of CFC danger in 1974, changed the course of policy. Indian scientists have contributed too: India has long-running research stations in Antarctica, such as Maitri and Bharati, where ozone measurements are made.

What is the Montreal Protocol?

The Montreal Protocol is the 1987 international treaty that phases out the production and use of ozone-depleting substances, and it has been ratified by every country in the world. It is built on the Vienna Convention of 1985 and has been strengthened by several amendments and adjustments as science advanced. Its success lies in a clear schedule, trade controls that discourage non-members, regular scientific assessment and a funding mechanism.

That mechanism, the Multilateral Fund, pays developing countries, including India, for the extra costs of switching industry to safer substitutes. Developing countries were given longer timelines than developed ones, an arrangement known as common but differentiated responsibility. Scientific assessments suggest that the protocol has avoided very large increases in UV exposure and has also delivered a major climate benefit, since CFCs are also powerful greenhouse gases. Observations show the concentration of ozone-depleting chemicals in the atmosphere declining, and models project that the global ozone layer should recover around the middle of the century, with Antarctica taking longer, towards the latter part of the century.

What has India done under the Montreal Protocol?

India has complied with the Montreal Protocol and phased out the production and consumption of CFCs, halons and carbon tetrachloride by 2010, in line with the deadline for developing countries. It acceded to the Vienna Convention and the Montreal Protocol in 1992 and became eligible for funding from the Multilateral Fund, which supported the conversion of refrigerator, air conditioner, foam, aerosol and solvent industries.

The country set up an Ozone Cell in the environment ministry to coordinate the work and issued the Ozone Depleting Substances (Regulation and Control) Rules in 2000, which control production, import, export, sale and use. These rules have been amended several times to tighten the net, including bans on new equipment using controlled chemicals and a licensing system for trade. Training of refrigeration technicians in good servicing practice and the recovery and reuse of refrigerants were also supported. India has also been commended for continuing to meet its targets while its cooling and manufacturing sectors grew rapidly, though illegal trade in banned chemicals remains a risk that customs and enforcement agencies must watch for.

What are HCFCs and how is India phasing them out?

HCFCs, or hydrochlorofluorocarbons, are transitional chemicals that replaced CFCs in air conditioners, refrigeration, foams and solvents, and they harm ozone much less than CFCs but still harm it. The best known is HCFC-22, the traditional refrigerant in many Indian room air conditioners. Because they still deplete ozone and are greenhouse gases, the Montreal Protocol set a phase-out schedule for them as well.

For developing countries such as India, the schedule involved freezing consumption around 2013, then cutting it in steps, with reductions of 35 percent by 2020 and 67.5 percent by 2025, followed by a near-complete phase-out in 2030 that leaves only a small allowance for servicing existing equipment until 2040. India has pursued this through HCFC Phase-out Management Plans, supported by the Multilateral Fund, that cover manufacturing sectors such as air conditioning, foams and refrigeration servicing. Many manufacturers have moved to alternatives, with newer room air conditioners commonly using R-32 or, in some models, propane, rather than HCFC-22. These replacements bring their own trade-offs, which leads to the next chapter.

What is the Kigali Amendment and why does it matter to India?

The Kigali Amendment is a 2016 addition to the Montreal Protocol that requires countries to phase down hydrofluorocarbons or HFCs, which are the chemicals that replaced CFCs and HCFCs and which do not harm ozone but are potent greenhouse gases. It was agreed in Kigali, Rwanda, entered into force in 2019, and is estimated to avoid a few tenths of a degree Celsius of warming by the end of the century if fully implemented.

India ratified the amendment in 2021 after a Union Cabinet decision. As a developing country in the second group, it will freeze HFC consumption around 2028 and then cut it in steps, with a final reduction of about 85 percent by 2047 compared with its baseline. The Indian approach is to rely on domestic industry, domestic technology development and lower-impact alternatives, and the ozone rules have been extended to regulate HFCs. A byproduct chemical called HFC-23, released during the manufacture of HCFC-22, is a particularly potent warming agent and must be controlled or destroyed. The Kigali schedule is meaningful for India because demand for air conditioning is rising fast, so the choice of refrigerant now will shape emissions for decades. The table below compares the three main families of cooling chemicals.

What is the India Cooling Action Plan?

The India Cooling Action Plan is a national strategy launched in 2019 to meet the country’s rapidly growing demand for cooling while limiting the climate and ozone impacts of that growth. It was among the first plans of its kind in the world, looking across buildings, refrigeration and cold chains, transport air conditioning and servicing, over a twenty-year horizon to the late 2030s.

The plan set goals such as reducing cooling demand across sectors, cutting refrigerant demand through better technologies and servicing practices, and improving energy efficiency of cooling equipment, along with training technicians and promoting alternative refrigerants. It encourages passive cooling and better building design so that fewer machines are needed in the first place. Because cooling already accounts for a large share of peak electricity demand in hot Indian summers, efficient and ozone-friendly cooling is a public health measure, a climate measure and an energy security measure at the same time. The practical task is making sure affordable, efficient and low-impact cooling reaches ordinary households, not only premium buyers.

How is ground-level ozone different from the ozone layer?

Ground-level ozone is a harmful air pollutant formed near the surface when nitrogen oxides and volatile organic compounds react in sunlight, whereas the ozone layer is a protective shield high in the stratosphere. They are the same molecule in different places with opposite roles, which is the source of the common saying that ozone is good up high and bad nearby.

In India, ground-level ozone rises in sunny, stagnant weather, especially in spring and early summer across the Indo-Gangetic plain and in big cities, and it irritates the lungs, worsens asthma and damages crops such as wheat and rice. Studies suggest that ozone exposure may cut yields of some staple crops, though estimates vary. Ground-level ozone is not governed by the Montreal Protocol, and fixing the ozone layer does nothing to reduce it. Controlling it requires cutting vehicle, industrial and solvent emissions, which is the same effort that tackles photochemical smog. One of the most common misunderstandings is the claim that more ozone at ground level can patch the hole above; it cannot, because ozone does not travel upward in significant quantities.

Is the ozone layer recovering?

The ozone layer is recovering slowly, with scientific assessments reporting that it is on track to return to early-1980s levels over most of the world around the middle of the century and over Antarctica somewhat later. Atmospheric concentrations of the major ozone-depleting chemicals have fallen since the late 1990s, and measurements show ozone thickening in the upper stratosphere, which is the most direct sign of success.

Recovery is not automatic or simple. Natural variability, volcanic eruptions and wildfire smoke can influence ozone, and there have been alarms over illegal emissions of banned CFC-11 in the late 2010s, which were investigated and appear to have decreased afterwards. Climate change adds complexity, since cooling in the stratosphere and changing circulation affect ozone chemistry. For India, the key message is that continued compliance matters. The country’s job is to complete the HCFC phase-out, deliver the HFC phase-down, manage waste refrigerants properly and keep illegal trade in check, while teaching the public that a repaired ozone layer is a result of sustained cooperation rather than luck.

Bottom Line

The ozone layer shields India from damaging ultraviolet radiation, and the Montreal Protocol has begun to heal it. India has met its major milestones and now faces the next test of moving to climate-friendly cooling under the Kigali Amendment, while ground-level ozone remains a separate pollution problem to be tackled on its own.

Frequently Asked Questions

What is the ozone layer?

The ozone layer is a region of the stratosphere, roughly 15 to 35 kilometres above the ground, with a high concentration of ozone. It absorbs most of the sun’s harmful ultraviolet radiation.

Is there an ozone hole over India?

No. The ozone hole forms seasonally over Antarctica, and India has not experienced anything comparable. India’s ozone column is naturally thinner than at higher latitudes, but this is a normal feature of the tropics.

What is India’s role in the Montreal Protocol?

India joined in 1992 and phased out CFCs, halons and carbon tetrachloride by 2010. It is now phasing out HCFCs and, since ratifying the Kigali Amendment in 2021, phasing down HFCs.

What is the Kigali Amendment?

It is a 2016 amendment to the Montreal Protocol that phases down HFCs, which do not harm ozone but are strong greenhouse gases. India will begin with a freeze around 2028 and reach a large reduction by 2047.

What is the India Cooling Action Plan?

It is a national plan launched in 2019 to manage rising cooling demand while reducing refrigerant use, improving efficiency and limiting climate and ozone impacts. It covers buildings, refrigeration and servicing over about two decades.

Is ground-level ozone the same as the ozone layer?

It is the same molecule but plays the opposite role. The ozone layer protects life, whereas ground-level ozone is a pollutant that harms lungs and crops.

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