Dimitris Akritidis

As part of the second Tropospheric Ozone Assessment Report (TOAR-II), we synthesize global observations and observationally constrained estimates of surface-level ozone (O3) with contemporary literature to characterize the global distribution and trends of long-term O3 exposure, focusing on two health-relevant metrics and health impacts attributable to long-term exposure. The highest 2016–2020 surface-level O3 concentrations are observed or estimated in South Asia, eastern China, and parts of the Middle East and North Africa. From 2000 to 2020, O3 declined across southeastern North America and parts of Eastern Europe, while the largest increases occurred in South Asia and Sub-Saharan Africa. Global premature mortality from chronic obstructive pulmonary disease (COPD) attributable to long-term O3 exposure nearly doubled between 2000 and 2020, reaching approximately 500 000 deaths annually. This overall increase obscures decreasing attributable deaths across North America and Europe and increasing deaths across large parts of the Global South. To spur high-quality, robust research on O3 health impacts, we summarize state-of-the-science practices for conducting health impact assessments (HIAs) and characterizing associated uncertainty. We also call for expanded in situ monitoring, improved health datasets and epidemiologic evidence, and sustained precursor emission reductions to clarify and limit the growing global health burden of O3 under climate change and demographic shifts. This article is part of the theme issue ‘Tropospheric Ozone Assessment Report II’.

Exposure to fine particulate matter (PM2.5) is a major risk for human health. Over recent decades, air-quality standards have become progressively more stringent, reflecting growing evidence of PM2.5 as a public health concern. At the country level, differences in PM2.5 exposure experienced and caused by countries, combined with differences in economic and social characteristics, shape inequalities in exposure to air pollution. We exploit a set of roughly 180 global simulations with the ECHAM/MESSy2 Atmospheric Chemistry model (EMAC) for the period 2014–2019, in which anthropogenic emissions from each country are excluded to quantify country-to-country contributions to PM2.5 levels. Within this framework, we assess the role of domestic and transboundary anthropogenic pollution in shaping PM2.5 exposure at global and national scales under different air-quality standards. Combining the country-to-country air pollution exchanges with socioeconomic indicators, we aim to identify disparities in the way countries experience and shape exposure to PM2.5, thereby unraveling air pollution inequalities across nations

We present a global assessment of excess mortality attributable to long-term exposure to fine particulate matter (PM2.5) over the period 2000–2021, using satellite-derived PM2.5 concentration estimates. Mortality burdens attributable to PM2.5 exposure are quantified for this period using the FUSION relative risk model for non-communicable diseases (NCDs) and lower respiratory infections (LRIs). We analyze global and regional trends in PM2.5 exposure and associated excess mortality and assess the contribution of key driving factors. By integrating population-based thresholds with gross domestic product (GDP) data, we examine disparities between rural and urban areas as well as between low- and high-income regions. Our findings reveal substantial cross-country heterogeneity in the mitigation of PM2.5-related health impacts and identify potential pathways for reducing pollution-induced mortality.Funded by the European Union and the Swiss State Secretariat for Education, Research and Innovation (SERI). Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union, or the European Health and Digital Executive Agency (HADEA) or the SERI. Neither the European Union nor the granting authorities can be held responsible for them, MARKOPOLO project GA No:101156161.

Here, we assess the amplification of near-surface warming in the Mediterranean (MED) resulting from global anthropogenic aerosol (AA) reductions, based on simulations from CMIP6 Earth system models (ESMs). Temperature and radiative responses are investigated over the MED. The effective radiative forcing (ERF) and near-surface temperature (TAS) exhibit decreasing trends until around 1980 followed by increasing trends, driven by air pollution control policies. The annual mean ERF at the top-of-atmosphere over the MED changes by 2.37±1.06 W m^-2 between the peak AA period (1970–1979) and the near-present period (2005–2014). During this interval, the annual mean TAS increases by 0.67±0.37 °C. Overall, the multi-model ensemble shows a robust amplification of warming over the MED on annual scale resulting from global AA reductions from 1970–1979 to 2005–2014, in good agreement with observational datasets over land. The model simulations indicate that AAs are responsible for 49 % (39 %) of the annual (summer) warming between the two periods. In the winter, ESMs produce an overestimated warming of 1.19 °C, with AAs contributing 60 % to this warming. Finally, we show that circulation changes caused by AA reductions can play an additional role in the redistribution of regional temperature changes apart from the radiative effects per se. Our results reveal a strong link between the recent acceleration of MED warming and global AA decreases, which unmask additional greenhouse gas-driven warming. This study highlights the sensitivity of the MED to global emission changes and the need for climate policies that couple air quality improvements with rapid greenhouse gas mitigation.

Here, we assess the amplification of near-surface warming in the Mediterranean (MED) resulting from global anthropogenic aerosol (AA) reductions, based on simulations from CMIP6 Earth system models (ESMs). Temperature and radiative responses are investigated over the MED. The effective radiative forcing (ERF) and near-surface temperature (TAS) exhibit decreasing trends until around 1980 followed by increasing trends, driven by air pollution control policies. The annual mean ERF at the top-of-atmosphere over the MED changes by 2.37±1.06 W m^-2 between the peak AA period (1970–1979) and the near-present period (2005–2014). During this interval, the annual mean TAS increases by 0.67±0.37 °C. Overall, the multi-model ensemble shows a robust amplification of warming over the MED on annual scale resulting from global AA reductions from 1970–1979 to 2005–2014, in good agreement with observational datasets over land. The model simulations indicate that AAs are responsible for 49 % (39 %) of the annual (summer) warming between the two periods. In the winter, ESMs produce an overestimated warming of 1.19 °C, with AAs contributing 60 % to this warming. Finally, we show that circulation changes caused by AA reductions can play an additional role in the redistribution of regional temperature changes apart from the radiative effects per se. Our results reveal a strong link between the recent acceleration of MED warming and global AA decreases, which unmask additional greenhouse gas-driven warming. This study highlights the sensitivity of the MED to global emission changes and the need for climate policies that couple air quality improvements with rapid greenhouse gas mitigation.

Here, we assess the amplification of near-surface warming in the Mediterranean (MED) resulting from global anthropogenic aerosol (AA) reductions, based on simulations from CMIP6 Earth system models (ESMs). Temperature and radiative responses are investigated over the MED. The effective radiative forcing (ERF) and near-surface temperature (TAS) exhibit decreasing trends until around 1980 followed by increasing trends, driven by air pollution control policies. The annual mean ERF at the top-of-atmosphere over the MED changes by 2.37±1.06 W m^-2 between the peak AA period (1970–1979) and the near-present period (2005–2014). During this interval, the annual mean TAS increases by 0.67±0.37 °C. Overall, the multi-model ensemble shows a robust amplification of warming over the MED on annual scale resulting from global AA reductions from 1970–1979 to 2005–2014, in good agreement with observational datasets over land. The model simulations indicate that AAs are responsible for 49 % (39 %) of the annual (summer) warming between the two periods. In the winter, ESMs produce an overestimated warming of 1.19 °C, with AAs contributing 60 % to this warming. Finally, we show that circulation changes caused by AA reductions can play an additional role in the redistribution of regional temperature changes apart from the radiative effects per se. Our results reveal a strong link between the recent acceleration of MED warming and global AA decreases, which unmask additional greenhouse gas-driven warming. This study highlights the sensitivity of the MED to global emission changes and the need for climate policies that couple air quality improvements with rapid greenhouse gas mitigation.

Here, we assess the amplification of near-surface warming in the Mediterranean (MED) resulting from global anthropogenic aerosol (AA) reductions, based on simulations from CMIP6 Earth system models (ESMs). Temperature and radiative responses are investigated over the MED. The effective radiative forcing (ERF) and near-surface temperature (TAS) exhibit decreasing trends until around 1980 followed by increasing trends, driven by air pollution control policies. The annual mean ERF at the top-of-atmosphere over the MED changes by 2.37±1.06 W m^-2 between the peak AA period (1970–1979) and the near-present period (2005–2014). During this interval, the annual mean TAS increases by 0.67±0.37 °C. Overall, the multi-model ensemble shows a robust amplification of warming over the MED on annual scale resulting from global AA reductions from 1970–1979 to 2005–2014, in good agreement with observational datasets over land. The model simulations indicate that AAs are responsible for 49 % (39 %) of the annual (summer) warming between the two periods. In the winter, ESMs produce an overestimated warming of 1.19 °C, with AAs contributing 60 % to this warming. Finally, we show that circulation changes caused by AA reductions can play an additional role in the redistribution of regional temperature changes apart from the radiative effects per se. Our results reveal a strong link between the recent acceleration of MED warming and global AA decreases, which unmask additional greenhouse gas-driven warming. This study highlights the sensitivity of the MED to global emission changes and the need for climate policies that couple air quality improvements with rapid greenhouse gas mitigation.

Here, we assess the amplification of near-surface warming in the Mediterranean (MED) resulting from global anthropogenic aerosol (AA) reductions, based on simulations from CMIP6 Earth system models (ESMs). Temperature and radiative responses are investigated over the MED. The effective radiative forcing (ERF) and near-surface temperature (TAS) exhibit decreasing trends until around 1980 followed by increasing trends, driven by air pollution control policies. The annual mean ERF at the top-of-atmosphere over the MED changes by 2.37±1.06 W m^-2 between the peak AA period (1970–1979) and the near-present period (2005–2014). During this interval, the annual mean TAS increases by 0.67±0.37 °C. Overall, the multi-model ensemble shows a robust amplification of warming over the MED on annual scale resulting from global AA reductions from 1970–1979 to 2005–2014, in good agreement with observational datasets over land. The model simulations indicate that AAs are responsible for 49 % (39 %) of the annual (summer) warming between the two periods. In the winter, ESMs produce an overestimated warming of 1.19 °C, with AAs contributing 60 % to this warming. Finally, we show that circulation changes caused by AA reductions can play an additional role in the redistribution of regional temperature changes apart from the radiative effects per se. Our results reveal a strong link between the recent acceleration of MED warming and global AA decreases, which unmask additional greenhouse gas-driven warming. This study highlights the sensitivity of the MED to global emission changes and the need for climate policies that couple air quality improvements with rapid greenhouse gas mitigation.