Eastern Mediterranean Health Journal | All issues | Volume 31 2025 | Volume 31, issue 3 | Using time series studies to unravel the short-term health effects of particulate matter air pollution in Eastern Mediterranean Region

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Using time series studies to unravel the short-term health effects of particulate matter air pollution in Eastern Mediterranean Region

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Commentary

Aurelio Tobías1, Massimo Stafoggia2 Sophie Gumy3, Mazen Malkawi4 and Heba Safi4

1Institute of Environmental Assessment and Water Research, National Spanish Research Council, Barcelona, Spain. 2Department of Epidemiology, Lazio Region Health Service, ASL Roma 1, Rome, Italy. 3Department of Environment, Climate Change and Health, World Health Organization, Geneva, Switzerland. 4Healthier Populations Department, World Health Organization Regional Office of the Eastern Mediterranean, Amman, Jordan (Correspondence to Mazen Malkawi: This e-mail address is being protected from spambots. You need JavaScript enabled to view it )

Keywords: time series study, particulate matter, air pollution, public health, Eastern Mediterranean

Received: 25/05/2024; Accepted: 04/12/2024

Citation: Tobías A, Stafoggia M, Gumy S, Malkawi M, Safi H. Using time-series studies to unravel the short-term health effects of particulate matter air pollution in Eastern Mediterranean Region. East Mediterr Health J. 2025;31(3):160–162. https://doi.org/10.26719/2025.31.3.160.

Copyright © Authors 2025; Licensee: World Health Organization. EMHJ is an open access journal. This paper is available under the Creative Commons Attribution Non-Commercial ShareAlike 3.0 IGO licence (CC BY-NC-SA 3.0 IGO; https://creativecommons.org/licenses/by-nc-sa/3.0/igo)

Background

Particulate matter (PM) air pollution poses a significant threat to public health globally, with numerous studies linking it to adverse health outcomes (1–3). Time series regression studies have been widely used in investigating the short-term mortality and morbidity due to PM, providing substantial information to derive and upgrade the WHO air quality guidelines values for acute exposure to PM < 2.5 µm (PM2.5) and PM < 10 µm (PM10) (4). The Eastern Mediterranean Region (EMR) is characterized by countries with varying levels of air pollution exposure, industrialization, socio-economic gradients, and population density. A common environmental challenge shared by EMR countries is the direct influence of sand and dust storms, and there is no precise distinction between sand and dust storms, because there is a continuum of particle sizes in any storm. Desert dust events are often associated with substantial increases in measured concentrations of both PM10 and PM2.5 size fractions (4).

Understanding the health effects of PM air pollution is particularly challenging due to the complexity of the air quality mixture from composite source profiles (5,6). Although the region has the highest levels of PM air pollution, there are very few studies evaluating its acute health effects. Among the 66 studies in a systematic review commissioned by WHO to inform the air quality guidelines, none was conducted in the EMR (2). Similarly, the most extensive study ever conducted, with data from 652 cities, to assess the association of short-term mortality with PM, only included data from one site (Kuwait City) in the region (7).

Challenges in assessing the health effects of PM air pollution

Considering the lack of robust evidence from studies in dusty environments, the health impact assessment of ambient air pollution is being conducted using exposure-response functions of non-dusty environments (8). Unless additional evidence is forthcoming, this approach relies on the assumption that the health risk per microgram of dust is comparable to that of other PM constituents, with the exception of sulphates and elemental carbon, for which there is good evidence of greater effects than other constituents (9). The question of including/excluding the dust fraction of PM in the health assessments remains unanswered; time series studies conducted in dusty environments will partially answer the question. However, the frequent presence of sand and dust storm introduces several challenges in assessing the short-term effects of PM pollution in the EMR. First, sand and dust storms can significantly increase PM concentrations, leading to acute health impact, mainly exacerbation of cardiovascular events and respiratory diseases (10). Second, the composition of PM during dust events is diverse, containing not only mineral dust but also pollutants from anthropogenic sources, making it challenging to attribute health effects solely to PM exposure (5). Third, the interaction between desert dust particles and other pollutants may alter their physical and chemical properties, further complicating the estimation of health effects (5,6). Among these complexities, epidemiological time series studies offer a critical approach to disentangling the immediate health consequences of PM pollution from different sources during sand and dust storm events (6).

Promoting international collaboration and building capacity

Insights from multilocation time series studies have helped in developing appropriate evidence-based policies and interventions to mitigate the health impacts of PM pollution. There are numerous examples of multi-location global (7) and regional studies in Europe (11,12), United States (13), Latin America (14), and Asia (15). However, no collaborative effort has yet been made to conduct a multi-location study in the EMR. Given the transboundary nature of sand and dust storms, international collaboration is essential for conducting comprehensive time series studies and addressing the health impacts of PM air pollution in this region (16). Collaborative research initiatives can facilitate data sharing, harmonize methodologies and strengthen research capacities across countries in the region.

It is important to note that daily mortality counts for time series studies are not encumbered by confidentiality or ethical concerns, because they represent aggregate statistics and not individualized information. Open data sharing and transparency will be essential for fostering collaborative efforts that will facilitate comprehensive understanding of the complex interplay between air quality and public health in the region. Therefore, engaging governments, regulatory agencies and other stakeholders in this research endeavour would enhance understanding of the socioeconomic and cultural factors influencing vulnerability to PM air pollution, thereby enabling more targeted interventions and adaptation strategies in the current climate change scenario (17).

Conclusion

Despite the abundance of evidence on the short-term health effects of PM air pollution, there is an urgent need to conduct epidemiological studies to elucidate the health consequences in specific environments like the WHO EMR. The complexity of PM exposure exacerbated by frequent sand and dust storms underscores the importance of conducting time series studies to elucidate its immediate health effects. Although this commentary focuses on the short-term health impact of PM pollution in the EMR, we acknowledge the need for cohort epidemiological studies to understand the long-term health impact. There is a clear need to study the long-term health impact of chronic PM exposure to complement our understanding of the health burden associated with sand and dust storms. Using rigorous methodologies and fostering international collaboration, stakeholders in the region can generate actionable insights to inform policy decisions, protect public health and build resilience against the impacts of PM air pollution in this unique environmental context.

Conflicting of interest: None declared.

Funding: None.

References

  1. Héroux ME, Anderson HR, Atkinson R, Brunekreef B, Cohen A, Forastiere F, et al. Quantifying the health impacts of ambient air pollutants: recommendations of a WHO/Europe project. Int J Public Health 2015;60(5):619-27. doi: 10.1007/s00038-015-0690-y.
  2. Orellano P, Reynoso J, Quaranta N, Bardach A, Ciapponi A. Short-term exposure to particulate matter (PM10 and PM2.5), nitrogen dioxide (NO2), and ozone (O3) and all-cause and cause-specific mortality: Systematic review and meta-analysis. Environ Int. 2020;142:105876. doi: 10.1016/j.envint.2020.105876.
  3. Rückerl R, Schneider A, Breitner S, Cyrys J, Peters A. Health effects of particulate air pollution: A review of epidemiological evidence. Inhal Toxicol. 2011;23(10):555-92. doi: 10.3109/08958378.2011.593587.
  4. World Health Organization. WHO global air quality guidelines: Particulate matter (PM2.5 and PM10), ozone, nitrogen dioxide, sulfur dioxide and carbon monoxide. Geneva: World Health Organization, 2021. https://iris.who.int/bitstream/handle/10665/345329/9789240034228-eng.pdf.
  5. Querol X, Tobías A, Pérez N, Karanasiou A, Amato F, Stafoggia M, et al. Monitoring the impact of desert dust outbreaks for air quality for health studies. Environ Int. 2019;130:104867. doi: 10.1016/j.envint.2019.05.061.
  6. Tobías A, Stafoggia M. Modeling desert dust exposures in epidemiologic short-term health effects studies. Epidemiology 2020;31(6):788-795. doi: 10.1097/EDE.0000000000001255.
  7. Liu C, Chen R, Sera F, Vicedo-Cabrera AM, Guo Y, Tong S, et al. Ambient particulate air pollution and daily mortality in 652 cities. N Engl J Med. 2019;381(8):705-715. doi: 10.1056/NEJMoa1817364.
  8. Ostro B, Awe Y, Sanchez-Triana E. When the dust settles: A review of the health implications of the dust component of air pollution. Washington DC: International Bank for Reconstruction and Development/The World Bank 2021. https://documents1.worldbank.org/curated/en/918051630707070934/pdf/When-the-Dust-Settles-A-Review-of-the-Health-Implications-of-the-Dust-Component-of-Air-Pollution.pdf.
  9. United States Environment Protection Agency. Integrated Science Assessment (ISA) for particulate matter (Final Report, Dec 2019). Washington DC: United States Environment Protection Agency, 2019. https://cfpub.epa.gov/ncea/isa/recordisplay.cfm?deid=347534.
  10. Lwin KS, Tobias A, Chua PL, Yuan L, Thawonmas R, Ith S, et al. Effects of desert dust and sandstorms on human health: A scoping review. Geohealth 2023;7(3):e2022GH000728. doi: 10.1029/2022GH000728.
  11. Katsouyanni K, Schwartz J, Spix C, Touloumi G, Zmirou D, Zanobetti A, et al. Short term effects of air pollution on health: a European approach using epidemiologic time series data: the APHEA protocol. J Epidemiol Community Health 1996;50 Suppl 1(Suppl 1):S12-8. doi: 10.1136/jech.50.suppl_1.s12.
  12. Stafoggia M, Zauli-Sajani S, Pey J, Samoli E, Alessandrini E, Basagaña X, et al. Desert dust outbreaks in Southern Europe: Contribution to daily PM10 concentrations and short-term associations with mortality and hospital admissions. Environ Health Perspect 2016;124(4):413-9. doi: 10.1289/ehp.1409164.
  13. Samet JM, Dominici F, Zeger SL, Schwartz J, Dockery DW. The National Morbidity, Mortality, and Air Pollution Study. Part I: Methods and methodologic issues. Res Rep Health Eff Inst. 2000;(94 Pt 1):5-14; discussion 75-84. PMID: 11098531.
  14. Romieu I, Gouveia N, Cifuentes LA, de Leon AP, Junger W, Vera J, et al. Multicity study of air pollution and mortality in Latin America (the ESCALA study). Res Rep Health Eff Inst. 2012;(171):5-86. PMID: 23311234.
  15. Wong CM, Vichit-Vadakan N, Vajanapoom N, Ostro B, Thach TQ, Chau PY, et al. Part 5. Public health and air pollution in Asia (PAPA): a combined analysis of four studies of air pollution and mortality. Res Rep Health Eff Inst. 2010;(154):377-418. PMID: 21446215.
  16. Mokammel A, Malkawi M, Momeniha F, Safi HA, Niazi S, Yousefian F et al. Assessing capabilities of conducted ambient air pollution health effects studies in 22 Eastern Mediterranean countries to adopt air quality standards: a review. J Environ Health Sci Engineering 2023;21(2):295-304. doi: https://doi.org/10.1007/s40201-023-00862-1.
  17. Saadeh R, Khader Y, Malkawi M, Allouh MZ. Communicating the Risks of Air Pollution to the Public: A Perspective from Jordan and Lebanon. Environ Health Insights. 2022;16:11786302221127851. doi: 10.1177/11786302221127851.