Air pollution and atmospheric variables in Türkiye: A comprehensive analysis

Abstract

This study examines particulate matter (PM₁₀) and sulphur dioxide (SO₂) concentrations in Türkiye, one of the world's 20 largest economies with a population of more than 86 million people. The analysis covers from 2015 to 2019, a period during which pollutant levels frequently exceeded international air quality standards. While anthropogenic emissions are significant contributors, atmospheric variables also play a crucial role in pollutant dispersion and dilution. The research investigates how temperature, relative humidity, wind speed, precipitation, and boundary layer height affect pollutant concentrations in this country. Using a generalised additive model (GAM) and conducting a sensitivity analysis, the study explores seasonal and regional variations in the influence of these atmospheric variables across Türkiye, offering a national, multivariable perspective. The analysis relies on hourly data to capture diurnal variations during summer and winter. Additionally, it provides projections of pollutant concentrations for 2030 and 2050 under two IPCC climate scenarios: one assuming strong mitigation measures (RCP 4.5) and the other representing high-emission conditions (RCP 8.5). The GAM outputs show that temperature, humidity, wind speed, and precipitation affect PM₁₀ and SO₂ differently across the country, with marked regional and seasonal variations. Winter PM₁₀ commonly peaks near ∼10 °C, whereas in several regions summer concentrations decline once temperatures exceed ∼30 °C; relative humidity is generally positively associated with PM₁₀ yet negatively with SO₂; stronger winds and precipitation coincide with lower pollutant levels (with PM₁₀ highest at low winds <5 m/s and notably reduced on days with ∼25 mm rainfall). Coastal regions show the strongest wind- and rain-related reductions in concentrations; interior continental and semi-arid regions display a weaker precipitation signal with a tighter humidity–PM₁₀ association; and high-elevation basins and valleys are characterised by heightened sensitivity to boundary-layer stability. Sensitivity analysis indicates that boundary-layer height and wind are the primary atmospheric drivers for PM₁₀, whereas SO₂ shows a weaker overall sensitivity to atmospheric factors. Projections about the influence of atmospheric variables on pollution for 2030 and 2050 suggest that PM₁₀ levels will generally decline across both seasons, while SO₂ concentrations are expected to rise during summer. The study highlights the increasing influence of climate change on air pollution, stressing the importance of region-specific air quality management strategies. By integrating mitigation and adaptation measures, the findings offer valuable insights for policymakers aiming to improve air quality and reduce health risks across Türkiye.