Impact of Aircraft Emissions on Stratospheric Ozone

Aircraft emissions, particularly nitrogen oxides (NOx), play a critical role in the chemistry of the stratosphere and have significant implications for stratospheric ozone levels. The stratospheric ozone layer is essential for protecting life on Earth from harmful ultraviolet (UV) radiation. However, human activities, including aviation, have introduced various pollutants that can disrupt the delicate balance of ozone production and destruction.

Aircraft engines emit NOx, which can lead to both the formation and depletion of ozone, depending on the altitude and atmospheric conditions. At cruising altitudes, typically between 10 and 12 kilometers, NOx can catalyze reactions that deplete ozone, particularly in the presence of other ozone-depleting substances (ODS) such as chlorine and bromine compounds (Mohanakumar, 2008) & (Masiol & Harrison, 2014). The emissions from aircraft are particularly concerning because they occur in the stratosphere, where the effects on ozone are more pronounced compared to ground-level emissions.

In addition to NOx, aircraft also emit water vapor and particulate matter, which can interact with ozone-depleting substances and influence stratospheric chemistry. The presence of water vapor can enhance the formation of polar stratospheric clouds, which facilitate the release of reactive chlorine species that contribute to ozone depletion (Ma et al., 2024). Furthermore, the growth of air traffic and the anticipated increase in aviation emissions pose ongoing challenges to the recovery of the ozone layer, which has been aided by international agreements such as the Montreal Protocol (Li & Newman, 2023).

The complexity of the interactions between aircraft emissions and stratospheric ozone necessitates a comprehensive understanding of the mechanisms involved, as well as the need for effective policy measures to mitigate their impact. As the aviation industry continues to expand, it is crucial to assess and manage the contributions of aircraft emissions to stratospheric ozone depletion to ensure the protection of this vital atmospheric layer.

Mechanisms of Ozone Depletion

Aircraft emissions, particularly nitrogen oxides (NOx), play a significant role in the depletion of stratospheric ozone through complex chemical mechanisms. NOx, which includes nitric oxide (NO) and nitrogen dioxide (NO2), contributes to ozone depletion at different altitudes. At lower altitudes (1 to 12 km), NOx can enhance ozone concentrations, acting as a greenhouse gas. However, at higher altitudes (15 to 30 km), where supersonic flights occur, NOx contributes to ozone depletion by facilitating reactions that lead to the breakdown of ozone (O3) into oxygen (O2) (Janić, 1999). The interaction of NOx with other ozone-depleting substances, such as chlorine and bromine compounds, further exacerbates this depletion, particularly in the presence of water vapor and particulate matter emitted from aircraft (Ma et al., 2024).
The presence of water vapor in the stratosphere can enhance the formation of polar stratospheric clouds, which provide surfaces for heterogeneous reactions that activate chlorine compounds, leading to increased ozone destruction (Ma et al., 2024). Particulate matter from aircraft emissions can also influence the chemical reactions occurring in the stratosphere, potentially altering the balance between ozone production and destruction (Masiol & Harrison, 2014).

Mechanisms of Ozone Depletion by Nitrogen Oxides (NOx)

NOx Emissions and Ozone Formation:

• Nitrogen oxides (NO and NO2, collectively referred to as NOx) are produced during combustion processes in aircraft engines. These compounds can enhance ozone concentrations in the lower troposphere but contribute to ozone depletion in the stratosphere (Janić, 1999).
• At altitudes from 15 to 30 km, where supersonic flights occur, NOx can catalyze the destruction of ozone. The reactions involve NOx facilitating the conversion of ozone (O3) into oxygen (O2), thereby reducing the overall ozone concentration (Janić, 1999).

Chemical Reactions:

• The primary reactions involving NOx in ozone depletion include:
  • NO + O3 → NO2 + O2
  • NO2 + O → NO + O2
• These reactions create a cycle where NOx can continuously convert ozone into oxygen without being permanently removed from the atmosphere, leading to significant ozone loss (Janić, 1999).

Interactions with Other Pollutants

Water Vapor:

• Water vapor (H2O) is another significant contributor to stratospheric chemistry. When emitted at high altitudes, it can lead to the formation of polar stratospheric clouds (PSCs), which provide surfaces for chemical reactions that activate chlorine compounds, further enhancing ozone depletion (Wittmer & Müller, 2021).
• The presence of water vapor can also influence the formation of nitric acid (HNO3) from NOx, which can lead to the removal of reactive nitrogen species from the gas phase, thereby affecting ozone levels (Ma et al., 2024).

Particulate Matter:

• Particulate matter from aircraft emissions can interact with ozone-depleting substances by providing surfaces for heterogeneous reactions. For example, sulfate aerosols can enhance the activation of chlorine and bromine compounds, which are critical in ozone destruction processes (Ma et al., 2024).
• The interaction of particulate matter with NOx can lead to the formation of secondary inorganic aerosols, which can further complicate the atmospheric chemistry and contribute to ozone depletion (Masiol & Harrison, 2014).

Overall Impact:

• The combined effects of NOx, water vapor, and particulate matter create a complex interplay in the stratosphere that can lead to both ozone depletion and changes in climate patterns. The presence of these pollutants can enhance the overall loading of ozone-depleting substances, complicating recovery efforts (Smith et al., 2024).

Quantifying Emissions

Current estimates indicate that commercial and military aircraft contribute significantly to NOx emissions at cruising altitudes, with subsonic aircraft producing approximately 2-4% of total man-made NOx emissions (Janić, 1999). The emissions from different aircraft types vary, with supersonic aircraft generally having a more pronounced impact on stratospheric ozone due to their operation at higher altitudes where ozone depletion processes are more active (Schumann et al., 2000b).

Current Estimates of NOx and Other Relevant Emissions

NOx Emissions:

• Aircraft emissions of nitrogen oxides (NOx) are significant contributors to stratospheric ozone depletion. Estimates indicate that in 2005, the NOx emitted during landing and take-off (LTO) cycles was approximately 0.23 Tg, accounting for about 8% of global aviation emissions (Masiol & Harrison, 2014).
• The emissions of NOx from aircraft are sensitive to engine thrust settings, with values ranging from 4 ± 1 g NOx per kg of fuel burned at idle to 29 ± 12 g NOx per kg of fuel burned at take-off power (Masiol & Harrison, 2014).

Other Emissions:

• In addition to NOx, aircraft also emit carbon monoxide (CO), unburned hydrocarbons (UHC), and particulate matter. The emissions of these pollutants can vary significantly based on the operational phase of the aircraft (e.g., take-off, cruising, landing) (Masiol & Harrison, 2014).
• The impact of these emissions on air quality and stratospheric chemistry is substantial, particularly in regions with high air traffic, such as the North Atlantic flight corridor (Schumann et al., 2000b).

Differences in Emissions from Aircraft Types

Subsonic vs. Supersonic Aircraft:

• Subsonic aircraft are the primary contributors to NOx emissions in the upper troposphere, with estimates suggesting that they contribute between 20% to 70% of the nitrogen oxides in that region, depending on the season (Schumann et al., 2000a).
• Supersonic aircraft, such as the Concorde, have been shown to produce higher levels of NOx emissions due to their operational altitudes and speeds. The emissions from these aircraft can have a more pronounced effect on stratospheric ozone due to the altitude at which they operate, where the ozone layer is more sensitive to NOx  (Prather, 2024).

Impact on Stratospheric Ozone:

• The emissions from subsonic aircraft primarily contribute to ozone depletion through catalytic cycles involving NOx, which can lead to increased concentrations of ozone-depleting species in the stratosphere (Stohl et al., 2003).
• In contrast, the emissions from supersonic aircraft can exacerbate ozone depletion due to their higher altitude operations, where the effects of NOx are more pronounced and can lead to significant ozone loss (Prather, 2024).

In summary, current estimates indicate that NOx emissions from commercial and military aircraft at cruising altitudes are substantial, with significant contributions from both subsonic and supersonic aircraft. The impact of these emissions on stratospheric ozone varies between aircraft types, with supersonic aircraft generally having a more detrimental effect due to their operational characteristics.

Temporal and Spatial Variability

Seasonal variations in aircraft traffic and atmospheric conditions significantly affect stratospheric ozone levels. For instance, during winter months, aircraft emissions of NOx are particularly impactful, contributing to ozone formation in the upper troposphere, while summer months see reduced concentrations of NOx and, consequently, lower ozone production (Janić, 1999). The spatial distribution of ozone depletion is closely linked to major flight corridors, with significant depletion observed in areas with high traffic density, such as the North Atlantic flight corridor (Schumann et al., 2000b).

Seasonal Variations in Aircraft Traffic and Atmospheric Conditions

Impact of Seasonal Variations:

• Seasonal variations in aircraft traffic significantly influence the levels of stratospheric ozone depletion. During winter months, aircraft emissions of nitrogen oxides (NOx) are particularly impactful, as they contribute to ozone formation in the upper troposphere. However, in the summer, the concentrations of NOx are lower, leading to reduced ozone production (Janić, 1999).
• The atmospheric conditions, such as temperature and humidity, also play a crucial role. For instance, the upper troposphere is often humid in autumn, which can lead to persistent contrails that further affect ozone levels (Schumann et al., 2000b). The presence of water vapor can enhance the formation of ozone-depleting substances through chemical reactions involving NOx and other pollutants (Masiol & Harrison, 2014).

Ozone Recovery and Seasonal Dynamics:

• The recovery of stratospheric ozone is influenced by both the seasonal patterns of aircraft emissions and the atmospheric dynamics that govern the transport of ozone and its precursors. The interplay between increased tropospheric ozone due to pollution and the depletion caused by halogens is complex and varies with the seasons (Prather, 2024).

Spatial Distribution of Ozone Depletion Related to Flight Corridors

Flight Corridors and Ozone Depletion:

• The spatial distribution of ozone depletion is closely linked to major flight corridors, particularly in regions with high air traffic. Aircraft emissions have been shown to significantly affect ozone levels in the upper troposphere and lower stratosphere, especially over the North Atlantic flight corridor, where emissions from aircraft can accumulate and lead to localized ozone depletion (Schumann et al., 2000b).
• Measurements indicate that aircraft emissions contribute to the abundance of nitrogen oxides in the atmosphere, which can enhance ozone concentrations in the lower troposphere but lead to depletion in the stratosphere, particularly at altitudes between 15 to 30 km (Janić, 1999).

Correlation with Aircraft Emissions:

• The correlation between aircraft emissions and ozone depletion is evident in the spatial patterns observed in satellite data. For example, the presence of ozone anomalies in the stratosphere can be linked to the flight paths of aircraft, with significant depletion observed in areas with high traffic density (Ma et al., 2024).
• Studies have shown that the emissions from aircraft flying at cruising altitudes contribute to both the depletion of ozone in the stratosphere and the enhancement of ozone in the troposphere, creating a complex feedback loop that varies spatially depending on flight routes and atmospheric conditions (Stohl et al., 2003).

In summary, seasonal variations in aircraft traffic and atmospheric conditions significantly affect stratospheric ozone levels, with distinct spatial patterns of depletion correlated with major flight corridors. The interplay between emissions and atmospheric chemistry is complex and requires ongoing monitoring and modeling to fully understand its implications for ozone recovery and environmental health.

Long-term Trends

The regulation of ozone-depleting substances, particularly through the Montreal Protocol, has led to a gradual recovery of the ozone layer. However, the relationship between aircraft emissions and stratospheric ozone levels remains complex. The continued growth of air traffic poses a challenge, as projected increases in aviation emissions could offset some of the recovery benefits achieved through the regulation of halocarbons. Studies suggest that while the ozone layer is expected to recover over the coming decades, the anticipated growth in air traffic could complicate this recovery (Li & Newman, 2023).

Influence of Regulation of Ozone-Depleting Substances

Impact of the Montreal Protocol:

• The Montreal Protocol, established in 1987, has been instrumental in phasing out the production and use of chlorofluorocarbons (CFCs) and other ODS. This regulatory framework has led to a significant reduction in the atmospheric concentrations of these substances, which are known to deplete stratospheric ozone (Li & Newman, 2023).
• As a result of these regulations, there has been a noted recovery of the ozone layer, particularly in the Antarctic region, where the ozone hole has shown signs of stabilization and potential recovery (Masiol & Harrison, 2014). The reduction of halogen levels in the stratosphere is expected to lead to a gradual increase in ozone concentrations over the coming decades.

Aircraft Emissions and Ozone Levels:

• Despite the positive effects of the Montreal Protocol, aircraft emissions, particularly nitrogen oxides (NOx), continue to pose a challenge. NOx can contribute to ozone formation in the troposphere but leads to ozone depletion in the stratosphere, especially at higher altitudes (Janić, 1999). The interaction between aircraft emissions and the declining levels of ODS creates a complex dynamic that influences stratospheric ozone levels.

Projected Long-Term Impacts of Increasing Air Traffic

Growth in Air Traffic:

• Projections indicate that global air traffic is expected to increase significantly in the coming decades. This growth will likely lead to higher emissions of NOx and other pollutants from aircraft, which could counteract some of the benefits gained from the reduction of ODS (Prather, 2024). The increase in air traffic is anticipated to exacerbate the challenges of managing stratospheric ozone levels.

Modeling Future Scenarios:

• Climate models suggest that the continued rise in aviation emissions could lead to a net increase in stratospheric ozone depletion, particularly if the emissions are not effectively managed (Li & Newman, 2023). The interaction between increased air traffic and the ongoing recovery of the ozone layer will be critical in determining future ozone levels.

Complex Interactions:

• The relationship between air traffic, emissions, and stratospheric ozone is complex. While the reduction of ODS is expected to facilitate ozone recovery, the projected increase in aviation emissions could introduce new challenges, potentially offsetting some of the recovery benefits (Prather, 2024). The long-term impacts will depend on the balance between these opposing forces.

In summary, the regulation of ozone-depleting substances has positively influenced stratospheric ozone levels, leading to signs of recovery. However, the projected increase in air traffic and associated emissions poses a significant challenge that could complicate these recovery efforts in the long term. Continued monitoring and management of aviation emissions will be essential to protect the ozone layer.

Modeling and Predictions

Current atmospheric models account for the impact of aircraft emissions on stratospheric ozone but have limitations. Many models rely on averaged data rather than real-time measurements, which can obscure specific processes affecting ozone levels (Stohl et al., 2003). Predictions indicate that as air traffic continues to grow, stratospheric ozone levels may be adversely affected, particularly if emissions are not effectively managed (Li & Newman, 2023).

Current Atmospheric Models and Limitations

Modeling Aircraft Emissions:

• Current atmospheric models, such as the Whole Atmosphere Community Climate Model (WACCM) and the GEOS-FP model, incorporate various emissions from aircraft, including nitrogen oxides (NOx) and particulate matter. These models simulate the transport and chemical reactions of these emissions in the atmosphere, particularly their effects on ozone production and depletion (Pan et al., 2022).
• The models utilize a range of observational data, including satellite measurements, to validate their predictions regarding the impact of aircraft emissions on stratospheric ozone levels (Pan et al., 2022).

Limitations of Models:

• One significant limitation of these models is their reliance on averaged data rather than real-time measurements, which can obscure the understanding of specific processes affecting ozone levels (Stohl et al., 2003). This can lead to inaccuracies in predicting the seasonal and spatial variability of ozone concentrations.
• Additionally, many models do not fully account for the complex interactions between stratospheric and tropospheric ozone, particularly how increases in tropospheric ozone due to pollution can influence stratospheric levels (Prather, 2024). The spillover of tropospheric ozone into the stratosphere complicates the assessment of ozone recovery and depletion (Prather, 2024).

Predictions for Future Stratospheric Ozone Levels

Impact of Global Air Traffic Growth:

• Predictions indicate that the anticipated growth in global air traffic, which is expected to increase by approximately 5% annually, will lead to higher emissions of NOx and other pollutants from aircraft (Masiol & Harrison, 2014). This growth could counteract some of the benefits gained from the reduction of ozone-depleting substances due to regulations like the Montreal Protocol (Masiol & Harrison, 2014).
• The increase in air traffic is likely to exacerbate ozone depletion in the stratosphere, particularly if emissions are not effectively managed (Li & Newman, 2023).

Changes in Aircraft Technology:

• Advances in aircraft technology, including more efficient engines and alternative fuels, may help mitigate some emissions. However, the overall impact of these improvements will depend on the rate of adoption and the scale of air traffic growth (Masiol & Harrison, 2014).
• Models predict that while the stratospheric ozone layer is expected to recover over the coming decades due to the phase-out of halocarbons, the recovery may be influenced by the increasing levels of tropospheric ozone and the dynamics of stratosphere-troposphere exchange (Li & Newman, 2023).

In summary, while current atmospheric models provide valuable insights into the impact of aircraft emissions on stratospheric ozone, they have limitations that can affect the accuracy of predictions. The anticipated growth in global air traffic poses a significant challenge to ozone recovery efforts, and the interplay between emissions, technological advancements, and atmospheric dynamics will be crucial in determining future ozone levels.

Comparative Analysis

When comparing the contributions of aircraft emissions to stratospheric ozone depletion with other sources, such as ground-based industrial emissions, it is evident that while aircraft emissions are significant, they are not the primary contributors to ozone depletion historically. Ground-based sources, particularly chlorofluorocarbons (CFCs), have had a more substantial impact (Mohanakumar, 2008). Natural phenomena, such as volcanic eruptions, can also exacerbate the effects of aircraft emissions on stratospheric ozone by releasing large quantities of sulfur dioxide, which can lead to increased ozone depletion (Mohanakumar, 2008).

Contributions of Aircraft Emissions vs. Other Sources of Ozone-Depleting Substances

Aircraft Emissions:

• Aircraft emissions, particularly nitrogen oxides (NOx), have a dual effect on ozone levels. At lower altitudes (1 to 12 km), NOx can enhance ozone concentrations, acting as a greenhouse gas. However, at higher altitudes (15 to 30 km), where supersonic flights occur, NOx contributes to ozone depletion (Janić, 1999). Estimates suggest that jet aircraft produce only 2-4% of the total man-made NOx emissions, but their impact on ozone depletion is significant due to the altitude at which they operate (Janić, 1999).

Ground-Based Industrial Emissions:

• Ground-based industrial emissions, including those from the use of chlorofluorocarbons (CFCs) and other halogenated compounds, have historically been the primary contributors to stratospheric ozone depletion. Without the Montreal Protocol, the stratospheric abundances of chlorine and bromine from these sources would have increased significantly, leading to much larger ozone losses than currently observed (Mohanakumar, 2008). The regulation of these substances has led to a notable decrease in their atmospheric concentrations, contributing to the recovery of the ozone layer (Mohanakumar, 2008).

Comparative Impact:

• While aircraft emissions contribute to ozone depletion, their overall impact is less than that of ground-based industrial sources, particularly in the context of historical emissions. The success of international agreements like the Montreal Protocol has significantly reduced the contributions from industrial sources, while aircraft emissions continue to pose a challenge, especially with the projected growth in air traffic (Masiol & Harrison, 2014).

Role of Natural Phenomena

Volcanic Eruptions:

• Volcanic eruptions play a significant role in stratospheric chemistry and can exacerbate ozone depletion. Eruptions release large quantities of sulfur dioxide (SO2) and other gases that can lead to the formation of sulfate aerosols in the stratosphere. These aerosols can enhance the heterogeneous reactions that activate chlorine compounds, leading to increased ozone depletion (Mohanakumar, 2008). For instance, the eruption of Mount Pinatubo in 1991 resulted in significant stratospheric cooling and changes in ozone levels due to the interaction of volcanic aerosols with ozone-depleting substances (Mohanakumar, 2008).

Mitigation Effects:

• On the other hand, volcanic eruptions can also have a mitigating effect on ozone depletion by temporarily increasing the amount of particulate matter in the stratosphere, which can scatter sunlight and reduce the intensity of UV radiation reaching the Earth’s surface (Mohanakumar, 2008). However, the overall impact of volcanic activity tends to be complex and context-dependent, often exacerbating the effects of existing ozone-depleting substances rather than providing a long-term solution.

In summary, while aircraft emissions contribute to stratospheric ozone depletion, their impact is comparatively less significant than that of ground-based industrial emissions, particularly those regulated under international agreements. Natural phenomena, such as volcanic eruptions, can both exacerbate and mitigate the effects of these emissions, highlighting the complex interactions within the stratospheric ozone system.

Policy and Mitigation Strategies

To mitigate the impact of aircraft emissions on stratospheric ozone depletion, several policy measures can be implemented. These include stricter emissions standards for aircraft, investment in cleaner technologies, and international agreements to limit aviation emissions. The effectiveness of current international agreements, such as the Montreal Protocol, in addressing aviation contributions to ozone depletion is still being evaluated, but there is a growing recognition of the need for targeted actions in the aviation sector (Li & Newman, 2023).

Policy Measures to Mitigate Aircraft Emissions

Implementation of Emission Standards:

• The International Civil Aviation Organization (ICAO) has established emission standards for new aircraft engines, which have been in place since the late 1970s. These standards aim to reduce emissions of key pollutants such as nitrogen oxides (NOx), carbon monoxide (CO), and unburned hydrocarbons (UHC) (Masiol & Harrison, 2014). Strengthening these standards and ensuring compliance can significantly mitigate the impact of aircraft emissions on stratospheric ozone.

Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA):

• CORSIA is a global initiative aimed at stabilizing CO2 emissions from international aviation at 2020 levels, allowing for growth in air traffic while offsetting emissions through various mechanisms  (Al-Rabeei et al.). The implementation of CORSIA is crucial for managing the aviation sector’s contributions to climate change and ozone depletion.

Promotion of Sustainable Aviation Fuels (SAF):

• The development and adoption of sustainable aviation fuels can significantly reduce the carbon footprint of the aviation industry. Policies that incentivize the production and use of SAF, such as subsidies or mandates, can help transition the industry towards more environmentally friendly fuel sources (Callister & McLachlan, 2024).

Investment in Research and Development:

• Governments and international bodies should invest in research and development of new technologies that enhance fuel efficiency and reduce emissions. This includes exploring alternative propulsion systems, such as electric and hydrogen-powered aircraft, which could play a role in reducing aviation’s environmental impact (Callister & McLachlan, 2024).

Regulatory Frameworks for Noise and Emissions:

• In addition to emissions, noise pollution from aircraft operations is a significant concern. Developing comprehensive regulations that address both emissions and noise can help mitigate the overall environmental impact of aviation (Al-Rabeei et al.).

Effectiveness of Current International Agreements

Montreal Protocol:

• The Montreal Protocol has been highly effective in phasing out ozone-depleting substances, particularly chlorofluorocarbons (CFCs). This international agreement has led to a significant reduction in the atmospheric concentrations of these substances, contributing to the recovery of the ozone layer (Mohanakumar, 2008). However, the protocol does not specifically address emissions from aviation, which remain a concern for stratospheric ozone depletion.

Limitations in Addressing Aviation Emissions:

• While the Montreal Protocol has successfully targeted halogenated compounds, the contributions of aviation emissions, particularly NOx, to ozone depletion are not adequately addressed. Current regulations primarily focus on ground-based sources of ozone-depleting substances, leaving a gap in the management of aviation-related emissions (Prather, 2024).

Need for Comprehensive International Frameworks:

• The effectiveness of international agreements in addressing aviation emissions is limited by the lack of a comprehensive global emissions trading system (ETS) and unified standards across countries. The establishment of a global ETS for aviation emissions could enhance accountability and drive reductions in emissions (Al-Rabeei et al.).

Conclusion on the Impact of Aircraft Emissions on Stratospheric Ozone

Aircraft emissions, particularly nitrogen oxides (NOx), play a significant role in the dynamics of stratospheric ozone. At lower altitudes, NOx can enhance ozone concentrations, acting as a greenhouse gas. However, at higher altitudes, particularly in the stratosphere (15 to 30 km), NOx contributes to ozone depletion through complex chemical reactions involving chlorine and bromine compounds (Janić, 1999) & (Prather, 2024). The emissions from aircraft, while constituting a smaller percentage of total NOx emissions (approximately 2-4%), have a disproportionate impact on ozone depletion due to the altitude at which they are released (Janić, 1999) .

The interaction of aircraft emissions with other pollutants, such as water vapor and particulate matter, further complicates the assessment of their impact on ozone levels. Water vapor can enhance the formation of polar stratospheric clouds, which facilitate the activation of chlorine compounds, leading to increased ozone destruction. Additionally, the presence of aerosols from aircraft emissions can influence stratospheric chemistry, potentially leading to both ozone depletion and changes in ozone distribution (Ma et al., 2024).

Regulatory measures, such as the Montreal Protocol, have successfully reduced the use of ozone-depleting substances, leading to some recovery of the ozone layer. However, the anticipated growth in global air traffic poses a significant challenge, as increased aircraft emissions could offset the benefits gained from these regulations. Current atmospheric models indicate that while the ozone layer is expected to recover over the coming decades, the growth in aviation emissions may complicate this recovery (Li & Newman, 2023).

In summary, while aircraft emissions contribute to both the depletion and enhancement of stratospheric ozone, their overall impact is complex and influenced by various factors, including altitude, chemical interactions, and regulatory measures. Continued monitoring and research are essential to fully understand and mitigate the effects of aviation on stratospheric ozone.

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