Dust air pollution and hospital visits for respiratory, cardiovascular, and eye diseases in Eastern Iran

Abstract

One of the most significant environmental concerns that has been spreading in recent years due to human interference and irrational use of natural resources is the phenomenon of dust. This study investigated the relationship between dust air pollution and the burden of daily hospital visits due to respiratory, cardiovascular, and eye diseases. In this cross-sectional study, data on dust air pollution were collected from the Environment office and data on daily visits to hospitals from the hospital information system (HIS) through a checklist. Data analysis was performed using SPSS 22 software and Pearson correlation coefficient at a significance level of < 0.05. The average dust air pollution index in the studied area was 2233.71 ± 4737.52 µg/m³. The mean number of hospital visits for various conditions were as follows: pneumonia, 63.76 ± 84.72; eye diseases, 46.8 ± 70.2; chronic obstructive pulmonary disease (COPD), 62.5 ± 83.3; asthma, 64.7 ± 87.0; dyspnea, 63.8 ± 90.8; and cardiovascular diseases, 56.5 ± 66.2 patients. A significant moderate positive linear correlation was found between dust air pollution levels and daily hospital visits for pneumonia, dyspnea, COPD, asthma, eye diseases, and cardiovascular diseases (p < 0.0001). As air pollution increased, the number of hospital visits for these conditions also rose. The strongest correlation was observed between dust air pollution and dyspnea (r = 0.497), while the weakest correlation was found between dust air pollution and eye diseases (r = 0.406). Exposure to dust air pollution was correlated with hospital admissions for respiratory diseases, such as pneumonia, asthma, and COPD, as well as cardiovascular diseases and eye issues. It seems that using personal protection strategies by habitants to reduce dust exposure and implementation of long-term strategies by policymakers for controlling dust air pollution especially dust controlling for this region are necessary.

Supplementary Information

The online version contains supplementary material available at 10.1038/s41598-025-29771-z.

Introduction

Dust, or fine dust, consists of sedimentary solid particles suspended in the atmosphere that are less than 50 microns in diameter. Dust particles with a diameter of less than 0.10 millimeters can remain airborne for extended periods^1,2 and present various risks to human health, the environment, and transportation safety around the globe³. Dust is emitted by mechanical processes such as desert dust storms (wind erosion) and fugitive processes from human activities (e.g. industrial emissions, construction, vehicles, and land use practices)^3,4. Long-range transport of dust can expose populations far from the source, making it a global health concern⁵. Measuring dust air pollution in meteorology utilizes ground-based (Particulate Matter Samplers, Optical Particle Counters, Gravimetric Analysis, and …), remote sensing (Satellite Observations, Light Detection and Ranging, and …), and modeling techniques (Dust Transport Models, Back-Trajectory Analysis, and Forecasting Systems) to accurately quantify particulate matter (PM), specifically PM10 and PM2.5 (particles smaller than 10 or 2.5 micrometers)^6,7.

Dust is not a uniform entity. Its composition varies significantly based on geographical location, meteorological conditions, and source⁸. This variability influences its health impacts. Factors such as mineral content (e.g., silica), biological components (e.g., fungal spores, bacteria), and anthropogenic pollutants (e.g., heavy metals, combustion particles) all play a role^9–11. Dust can trigger inflammation, oxidative stress, and airway hyper reactivity, leading to exacerbations of asthma, COPD, and other respiratory illnesses¹². It can also increase susceptibility to respiratory infections¹³. In addition, fine particulate matter can induce systemic inflammation, endothelial dysfunction, and increased blood coagulation, contributing to cardiovascular events like myocardial infarction and stroke¹⁴. Dust particles can cause mechanical irritation, leading to conjunctivitis, corneal abrasions, and dry eye syndrome¹⁵. In regions with frequent dust storms, these effects can be significant¹⁶. Desert dust, which is dispersed and transported by strong winds in the process of soil erosion, is a major source of particulate matter (PM) worldwide, especially in arid and semi-arid regions¹⁷.

The Sistan Plain is situated in the southeast of Iran and is climatically in the middle climate group. According to 30-year statistics from the Zabol Meteorological Department, this region experiences an average of over 300 dry days each year and 120 days of high-intensity wind¹⁸. In addition, the occurrence of continuous droughts and periodic fluctuations in the amount of water entering the Hamun River have challenged all aspects of the lives of the residents of this region, especially their health¹⁹. While the Sistan 120-day winds have been examined from various angles, the impact of dust pollution on environmental and human health has been overlooked²⁰. Zabol has the highest annual average of PM10 particles (372 µgr/m³) making it the most polluted city in the world regarding suspended particulate matter. The current level of pollution poses a significant threat to the health of residents in the province, particularly affecting children and the elderly. Therefore, it is crucial for researchers to focus more on studying the health effects of this issue.

Despite the growing body of research on the health impacts of air pollution, there remains a significant gap in region-specific studies addressing the effects of dust storms in southeastern Iran, particularly in the Sistan region. Most existing literature has focused on urban industrial pollutants, while the unique climatic and environmental conditions of Sistan—characterized by frequent and intense dust events driven by the 120-day wind—have received limited attention. Severe droughts and the desiccation of Hamoun lakes have transformed the area into one of the most active dust sources in Southwest Asia, posing serious health risks to local populations²¹. In addition, recent studies have highlighted the presence of potentially toxic elements in desert dust across Iranian regions, underscoring the need for localized investigations into their ecological and health consequences. This study aims to fill this gap by examining the relationship between dust storm exposure and hospital admissions in this underserved area, thereby contributing evidence to inform public health interventions and environmental policy²¹. Therefore, this study investigated the relationship between dust air pollution and the burden of daily hospital visits due to respiratory, cardiovascular, and eye diseases.

Methods

Study design and statistical population

This cross-sectional study included all habitants of affiliated Zabol University of Medical Sciences.

Inclusion and exclusion criteria

All records of patients admitted to hospitals affiliated with Zabol University of Medical Sciences during the study period which recorded in the hospital information system (HIS) were entered. Incomplete records of patients and missing data of dust air pollution were excluded.

Sampling method

Data were collected using a census method.

Data collection

Required data was collected using a researcher-developed checklist. This checklist consisted of daily admitted patients (admitted date, admission cause, and habitant place) and dust air pollution rate.

Study implementation

After approved the study, the number of admissions due to pneumonia, dyspnea, asthma, chronic obstructive pulmonary disease (COPD), cardiovascular diseases, and eye diseases was extracted from hospital information system (HIS) of affiliated hospitals of Zabol University of Medical Sciences (Amir al Momenin (Zabol), Sayed al Shohadaye Zahak, Shohadaye Hirmand, and Imam Khomeini (Zabol)) from 2024 March 20 to 2025 February 3. Daily dust air pollution concentration (µg/m³) were obtained from Air Quality Monitoring System (AQMS) of the Sistan region Environmental Protection Department. At the department’s meteorological station, PM2.5 and PM10 concentrations are measured using an Environmental Sediment Sampler (ESPS) device manufactured by Air and Water Pollution Monitoring Technologies and Energy Systems Company (Fanpaya). This device measures PM10 and PM2.5 concentrations simultaneously and gravitationally using two separate cyclones with a flow rate of 167 Lit/min. We used daily index in the analyses which is obtained by calculating the air quality index from 11:00 yesterday to 11:00 today.

Statistical analyses

Statistical analyses were performed using SPSS 22 software and descriptive indices such as mean, standard deviation (SD), median, minimum, and maximum. Analytical analyses were done using Pearson correlation coefficient at significance level of < 0.05. Time trend was done by polynomial trend line in Excel 2016.

Results

The average air pollution index in the studied area was 2233.71 ± 4737.52 µg/m³ from 20 − 3–2024 to 3 − 2–2025, with the maximum pollution level corresponding to 8th August 2024 with 18832.49 ppm and the minimum corresponding to 8th December 2024 with 4.83 ppm pollution. In general, air pollution in the Sistan region starts in late June, reaches its peak in August and decreases in late October. (Table 1; Fig. 1).

Table 1.

Mean dust air pollution (µg/m³) and number of hospital visits.

Index	Dust air pollution	Pneumonia	Dyspnea	COPD	Asthma	Eye diseases	Cardiovascular diseases
Mean	2233.7	63.8	63.8	62.5	64.7	46.8	56.5
Median	54.6	20.0	20.0	19.0	20.0	13.0	23.0
SD	4735.5	84.7	90.8	83.3	87.0	70.2	66.2
Minimum	4.83	0	4	4	4	0	4
Maximum	9223.37	386	460	468	632	368	312

Fig. 1.

Time trend of dust air pollution (µg/m³) in the Sistan region in from 20.03.2024 to 03.02.2025 and its polynomial trend line (order 2).

During this period, the average number of visits to selected hospitals due to pneumonia was 63.76 ± 84.72, dyspnea was 63.8 ± 90.8, COPD was 62.5 ± 83.3, asthma was 64.7 ± 87.0, eye diseases were 46.8 ± 70.2, and cardiovascular diseases were 56.5 ± 66.2.

As illustrated in Fig. 2, an increase in dust air pollution correlates with a rise in hospital visits for conditions such as pneumonia, eye diseases, dyspnea, COPD, asthma, and cardiovascular diseases. These visits typically begin one week after pollution levels start to rise in early August and decline with a two-week lag once pollution levels decrease.

Fig. 2.

Time trend of visits and its polynomial trend line (order 4) to the emergency department of selected hospitals in the Sistan region from 20.03.2024 to 03.02.2025 based on investigated diseases.

The results of the study showed that there is a moderate positive and significant correlation between dust air pollution and visits to selected hospitals due to pneumonia, dyspnea, COPD, asthma, eye diseases, and cardiovascular diseases (p < 0.0001), and with increasing dust air pollution concentration, the number of visits to hospitals due to the aforementioned diseases increases. The highest correlation was observed between dust air pollution and the number of visits due to dyspnea (r = 0.497) and the lowest correlation was observed between dust air pollution and eye diseases (r = 0.406). More details are provided in Table 2; Fig. 3.

Table 2.

Pearson correlation coefficient between dust air pollution (µg/m³) and the number of visits due to investigated diseases.

		Pneumonia	Eye diseases	COPD	Asthma	Dyspnea	Cardiovascular diseases
Dust air pollution	r (p-value)	0.447 (< 0.0001)	0.406 (< 0.0001)	0.452 (< 0.0001)	0.423 (< 0.0001)	0.497 (< 0.0001)	0.454 (< 0.0001)

Fig. 3.

Pearson correlation between dust air pollution and pneumonia, dyspnea, COPD, asthma, eye diseases, and cardiovascular diseases.

Discussion

This study aimed to examine the relationship between air pollution in terms of particulate matter, and the number of hospital visits for respiratory, cardiovascular, and eye diseases. The findings revealed increased levels of air pollution caused by fine dust have a positive linear correlation with a rise in hospital visits for respiratory diseases, such as pneumonia, asthma, and COPD, as well as cardiovascular diseases and eye issues. The average dust air pollution index in the studied area was 2233.71 µg/m³ and the mean number of hospital visits for pneumonia, dyspnea, COPD, asthma, eye diseases, and cardiovascular diseases were 63.76, dyspnea 63.8, 62.5, 64.7, 46.8, and 56.5 patients, respectively. These findings are consistent with previous research conducted in arid and semi-arid regions, where elevated particulate matter levels have been linked to adverse health outcomes such as Tong et al²²., Ghio et al²³., Rivas et al²⁴., Rodopoulou et al²⁵., Schweitzer et al²⁶., Shahsavani et al²⁷., Al-Taiar et al²⁸., Wang et al²⁹., Domínguez et al³⁰.

Exposure to PM2.5 is strongly associated with exacerbations of respiratory conditions, leading to higher hospital admissions, even at short-term periods³¹ and low concentrations^32,33. The biological mechanisms underlying these effects may include airway inflammation, oxidative stress, and exacerbation of pre-existing conditions, particularly among vulnerable populations. Particles smaller than 10 microns (PM10) deposit in the respiratory tract, preventing the function of respiratory cilia, and the accumulation of particles in the lung causes the secretion of proinflammatory cytokines such as IL-6 and TNF-α^26,34. As a result, when the concentration of fine dust increases, visits for COPD and asthma increase. A study in the United States showed that an increase in the amount of suspended particles PM10 and PM2.5 is directly related to an increase in hospital visits for respiratory diseases such as pneumonia, which is consistent with the results of the present study. Previous meta-analyses and cohort studies confirmed that each 10 µg/m³ increase in PM2.5 is associated with a 1–3% rise in hospital admissions³⁵. This agreement can be justified in terms of biological mechanism, because PM2.5 particles, when penetrating the pulmonary alveoli, activate the inflammatory response of the immune system²². In addition, recent pediatric data from 2025 further supports this, showing that air pollution spikes correlate with emergency admissions for acute respiratory problems in children, with fine dust playing a dominant role³⁶. Studies in Middle Eastern countries such as Kuwait and Iran have also confirmed that dust storms can lead to increased mortality from respiratory diseases^27,28. However, this is not consistent with the study by Merrifield et al³⁷.

The linear correlation extends to cardiovascular outcomes, where PM2.5 contributes to hospital visits by promoting endothelial dysfunction, thrombosis, and autonomic nervous system imbalance. Inhaled particles translocate systemically, inducing vascular inflammation and plaque instability, which can precipitate events like myocardial infarction or stroke^22,29,38. Fine particulate matter can also, enter the bloodstream and contribute to the formation of plaques in arteries, increase the risk of cardiovascular events, elevate blood pressure, disrupt the heart’s electrical activity and lead to irregular heart rhythms, and contributed to cardiovascular disease-related deaths^39,40. In the United States, there has been a reported increase of up to 12% in hospital admissions for cardiovascular disease on days with high levels of PM10 and PM2.5 air pollution²². In Middle Eastern countries, dust storms have been linked to higher mortality rates from cardiovascular diseases^27,28. A 2025 multi-city study in China reported increased risks of hospital admissions for cardiovascular diseases (CVDs) and subtypes with long-term PM2.5 exposure, showing a positive linear association across 184 cities from 2014 to 2017⁴¹. Short-term exposures similarly elevate risks; for example, a 2025 analysis found that ambient air pollutants, including PM2.5, were linked to higher CVD outpatient visits, with effect estimates indicating a dose-dependent increase. Long-term exposure windows also reveal positive associations with multiple CVD outcomes, such as ischemic heart disease and cerebrovascular events, as evidenced in a 2024 cohort study where three-year average PM2.5 levels correlated with first-time hospital admissions^42,43. Furthermore, interactions with environmental factors like low temperatures amplify these effects, with 2025 data showing higher CVD risks from PM2.5 in colder conditions⁴⁴. Wildfire-sourced PM2.5, a growing concern, was associated with cause-specific CVD hospital admissions in a 2024 time-series study, reinforcing the linear exposure-response curve⁴⁵. Overall, meta-analyses from this period highlight that PM2.5’s cardiovascular impacts involve both acute spikes and cumulative exposure, contributing to global CVD burden.

Although less studied than respiratory or cardiovascular effects, PM2.5 exposure correlates with ocular surface disorders, leading to increased hospital or outpatient visits for conditions like conjunctivitis and dry eye disease (DED) especially for the youngers, females and during warm seasons⁴⁶. Fine particles irritate the conjunctiva and cornea, causing oxidative stress, tear film instability, and inflammatory cytokine release. When dust particles come into direct contact with the conjunctiva of the eye, they activate inflammatory pathways, such as NF-κB. This activation has been identified as a significant factor contributing to the rise in cases of dry eye and conjunctivitis⁴⁷. studies conducted in South Korea, Kuwait, and Iran found that higher levels of particulate matter (PM10 and PM2.5) were linked to an increased number of hospital visits for eye diseases^27,28,47. Another 2025 study on air pollutants and daily outpatient visits for DED found positive associations with PM2.5, with risks peaking on the day of exposure⁴⁸. Investigating long-term effects were explored that chronic air pollution exposure increases visits for allergic conjunctivitis, with lagged effects persisting over days⁴⁹. Preclinical and epidemiological evidence further supports that PM exposure correlates with ocular dysfunction via oxidative mechanisms, often manifesting as eye irritation post-dust events⁵⁰. A global review in 2025 noted increased hospital admissions for eye irritation following dust storms, emphasizing the role of fine dust in climate-related ocular health impacts⁵¹. These associations, while generally acute, highlight the need for protective measures in polluted areas.

In summary, the positive linear correlation between fine dust air pollution and hospital visits for these conditions is well-substantiated by recent (2020–2025) epidemiological studies, including time-series analyses, cohort studies, and meta-reviews. Mechanisms such as inflammation and oxidative stress underpin these effects, with vulnerable populations (e.g., children, the elderly) at higher risk. Public health interventions, including emission reductions and air quality monitoring, are crucial to mitigate these impacts. The effects of air pollution can vary depending on individual susceptibility, exposure levels, and the specific pollutants involved. Therefore, according to these serious consequences of dust air pollution on human health, it is crucial to protect vulnerable populations, such as children, the elderly, and those with pre-existing health conditions from these risks⁵². Also, it’s important to stay informed general population about air quality and take precautions to minimize exposure, especially on days with high pollution levels⁵³. In addition, implementing long effect strategies for decline dust air pollution such as planting green belts and soil stabilization is necessary for each society⁵⁴. Also, the findings highlight the need for stringent air quality regulations and public health measures in areas with high dust pollution. Interventions such as early warning systems for dust storms, improved ventilation in healthcare facilities, and public education on protective measures (e.g., masks, indoor air purifiers) could mitigate the health burden. Generally, the results emphasize the necessities of implementation of preventive strategies by health policy-makers including: the implementation of long-term environmental interventions—such as soil stabilization initiatives and the establishment of green belts—to help mitigate the frequency and severity of dust storms; enhancing public awareness regarding air quality and promoting protective behaviors during high pollution episodes to reduce exposure-related health risks; prioritize targeted support for vulnerable groups, including children, the elderly, and individuals with chronic health conditions, who are disproportionately affected by air pollution; and strengthening healthcare infrastructure and resource allocation to ensure system resilience and responsiveness during periods of elevated patient admissions linked to environmental hazards.

This study is subject to several limitations that should be acknowledged. The absence of individual-level patient data restricted the ability to adjust for personal health behaviors and specific environmental exposures, which may have influenced the outcomes. Additionally, the geographic scope of the research was limited to a single region, thereby reducing the generalizability of the findings to broader populations. Furthermore, due to data constraints, other potential confounding factors—such as socioeconomic status, indoor air quality, and access to healthcare services—could not be adequately controlled, which may have introduced bias into the analysis.

Conclusion

The results of this study indicate a significant positive association between dust air pollution levels and hospital visits for multiple health conditions in the studied area. The data underscore the public health implications of dust air pollution and highlight the need for targeted interventions to mitigate its impact on vulnerable populations and reduce the burden on healthcare systems. In addition, implementation long-term strategies by policy makers for controlling dust air pollution especially dust controlling for this region are necessary.

Supplementary Information

Below is the link to the electronic supplementary material.

Author contributions

All authors contributed.

Data availability

The datasets generated during and analyzed during the current study are available from the corresponding author on reasonable request.

Declarations

Competing interests

The authors declare no competing interests.

Ethics

This study approved in ethics committee of Zabol University of Medical Sciences by IR.ZBMU.REC.1401.150 code. Prior to completing the questionnaires, participants completed informed consent forms and were assured of the confidentiality of their information and that individual data would not be disseminated. All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee, as well as with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.