Temporal Trends and Meteorological Associations of Particulate Matter and Gaseous Air Pollutants in Tehran, Iran (2017–2021)

Air pollution is a major environmental risk factor that contributes significantly to the global burden of disease, particularly through its impact on respiratory and cardiovascular health. The aim of this study is to investigate the temporal variations of ambient air pollutants and the influence of...

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Main Authors: Fatemeh Yousefian, Zohreh Afzali Borujeni, Fatemeh Akbarzadeh, Gholamreza Mostafaii
Format: Article
Language:English
Published: MDPI AG 2025-06-01
Series:Atmosphere
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Online Access:https://www.mdpi.com/2073-4433/16/6/683
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author Fatemeh Yousefian
Zohreh Afzali Borujeni
Fatemeh Akbarzadeh
Gholamreza Mostafaii
author_facet Fatemeh Yousefian
Zohreh Afzali Borujeni
Fatemeh Akbarzadeh
Gholamreza Mostafaii
author_sort Fatemeh Yousefian
collection DOAJ
description Air pollution is a major environmental risk factor that contributes significantly to the global burden of disease, particularly through its impact on respiratory and cardiovascular health. The aim of this study is to investigate the temporal variations of ambient air pollutants and the influence of MPs (MPs) on their concentrations in the metropolitan area of Tehran from 2017 to 2021. Hourly data for PM<sub>2.5</sub>, PM<sub>10</sub>, O<sub>3</sub>, NO<sub>2</sub>, SO<sub>2</sub>, and CO from all air quality monitoring stations were obtained. Effects of MPs for the same period were assessed. The results revealed that Tehran’s residents are continuously exposed to harmful levels of PM<sub>2.5</sub> (5.7 to 6.3 times), PM<sub>10</sub> (4.5–5.6 times), and NO<sub>2</sub> (8.7–10.0 times) that are significantly higher than the updated World Health Organization (WHO) air quality guidelines. All other air pollutants (except for O<sub>3</sub>) showed the lowest and highest concentrations during summer and winter, respectively. The highest concentration of O<sub>3</sub> was found on weekends (weekend effect), while other ambient air pollutants had higher levels on weekdays (holiday effect). Although other air pollutants exhibited two peaks, in the morning and late evening, the hourly concentration of O<sub>3</sub> reached its maximum level at 3:00 pm. Approximately 51% to 65% of the Air Quality Index (AQI) values were classified as unhealthy for sensitive groups. Throughout the study period, PM<sub>2.5</sub> was identified as the primary pollutant affecting air quality in Tehran. Among MPs, temperature was the most important factor in increasing the concentration of O<sub>3</sub>, while the other ambient pollutants decreased under the influence of wind speed. Given the current situation, effective and evidence-based air quality management strategies, like those that have been successfully applied elsewhere, are now a necessity to avoid the public health impact and economic losses from air pollution. Although this research focuses on Tehran as a model case of rapidly developing cities facing severe air quality challenges, the findings and recommendations have broader applicability to similar urban environments worldwide.
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spelling doaj-art-b90778fef5da49dcb4ef9329ca6d21ff2025-08-20T02:24:39ZengMDPI AGAtmosphere2073-44332025-06-0116668310.3390/atmos16060683Temporal Trends and Meteorological Associations of Particulate Matter and Gaseous Air Pollutants in Tehran, Iran (2017–2021)Fatemeh Yousefian0Zohreh Afzali Borujeni1Fatemeh Akbarzadeh2Gholamreza Mostafaii3Department of Environmental Health Engineering, Faculty of Health, Kashan University of Medical Sciences, Kashan 8715973474, IranDepartment of Environmental Health Engineering, Faculty of Health, Kashan University of Medical Sciences, Kashan 8715973474, IranDepartment of Environmental Health Engineering, Faculty of Health, Kashan University of Medical Sciences, Kashan 8715973474, IranDepartment of Environmental Health Engineering, Faculty of Health, Kashan University of Medical Sciences, Kashan 8715973474, IranAir pollution is a major environmental risk factor that contributes significantly to the global burden of disease, particularly through its impact on respiratory and cardiovascular health. The aim of this study is to investigate the temporal variations of ambient air pollutants and the influence of MPs (MPs) on their concentrations in the metropolitan area of Tehran from 2017 to 2021. Hourly data for PM<sub>2.5</sub>, PM<sub>10</sub>, O<sub>3</sub>, NO<sub>2</sub>, SO<sub>2</sub>, and CO from all air quality monitoring stations were obtained. Effects of MPs for the same period were assessed. The results revealed that Tehran’s residents are continuously exposed to harmful levels of PM<sub>2.5</sub> (5.7 to 6.3 times), PM<sub>10</sub> (4.5–5.6 times), and NO<sub>2</sub> (8.7–10.0 times) that are significantly higher than the updated World Health Organization (WHO) air quality guidelines. All other air pollutants (except for O<sub>3</sub>) showed the lowest and highest concentrations during summer and winter, respectively. The highest concentration of O<sub>3</sub> was found on weekends (weekend effect), while other ambient air pollutants had higher levels on weekdays (holiday effect). Although other air pollutants exhibited two peaks, in the morning and late evening, the hourly concentration of O<sub>3</sub> reached its maximum level at 3:00 pm. Approximately 51% to 65% of the Air Quality Index (AQI) values were classified as unhealthy for sensitive groups. Throughout the study period, PM<sub>2.5</sub> was identified as the primary pollutant affecting air quality in Tehran. Among MPs, temperature was the most important factor in increasing the concentration of O<sub>3</sub>, while the other ambient pollutants decreased under the influence of wind speed. Given the current situation, effective and evidence-based air quality management strategies, like those that have been successfully applied elsewhere, are now a necessity to avoid the public health impact and economic losses from air pollution. Although this research focuses on Tehran as a model case of rapidly developing cities facing severe air quality challenges, the findings and recommendations have broader applicability to similar urban environments worldwide.https://www.mdpi.com/2073-4433/16/6/683air pollution trendPM<sub>2.5</sub>TehranO<sub>3</sub>Air Quality Index (AQI)pollutant-weather correlation
spellingShingle Fatemeh Yousefian
Zohreh Afzali Borujeni
Fatemeh Akbarzadeh
Gholamreza Mostafaii
Temporal Trends and Meteorological Associations of Particulate Matter and Gaseous Air Pollutants in Tehran, Iran (2017–2021)
Atmosphere
air pollution trend
PM<sub>2.5</sub>
Tehran
O<sub>3</sub>
Air Quality Index (AQI)
pollutant-weather correlation
title Temporal Trends and Meteorological Associations of Particulate Matter and Gaseous Air Pollutants in Tehran, Iran (2017–2021)
title_full Temporal Trends and Meteorological Associations of Particulate Matter and Gaseous Air Pollutants in Tehran, Iran (2017–2021)
title_fullStr Temporal Trends and Meteorological Associations of Particulate Matter and Gaseous Air Pollutants in Tehran, Iran (2017–2021)
title_full_unstemmed Temporal Trends and Meteorological Associations of Particulate Matter and Gaseous Air Pollutants in Tehran, Iran (2017–2021)
title_short Temporal Trends and Meteorological Associations of Particulate Matter and Gaseous Air Pollutants in Tehran, Iran (2017–2021)
title_sort temporal trends and meteorological associations of particulate matter and gaseous air pollutants in tehran iran 2017 2021
topic air pollution trend
PM<sub>2.5</sub>
Tehran
O<sub>3</sub>
Air Quality Index (AQI)
pollutant-weather correlation
url https://www.mdpi.com/2073-4433/16/6/683
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