Iranian Journal of

Background and Objective: This study was conducted to investigate the long-term temporal trends and spatial variations of ambient PM₁₀, PM_2.5, O₃, concentrations in Tabriz city during the years 2006-2017.
Materials and Methods: Real-time hourly concentrations of PM₁₀, PM_2.5, O₃ measured at nine air quality monitoring stations (AQMSs) were obtained from the Tabriz Department of Environment (TDoE) during 2006-2017 and analyzed. Spatial and temporal variations of pollutants using the Mann-Kendall's test and Moran’s I index were analyzed.
Results: The results of this study showed that the annual trend of PM₁₀, PM_2.5 was decreasing but remained almost constant for O₃ during the study period. During some of the studied days, PM₁₀, PM_2.5 levels were exceeded greater than the WHO AQG and National standard levels. Moreover, the highest monthly mean concentrations of PM₁₀ in October (80.3 µg/m³), PM_2.5 in January (42.9 µg/m³) and O₃ in June (77.8 µg/m³) were observed. Comparison between the stations indicated that the Raste Kuche station was more polluted than other stations.
Conclusion: Effective control planning and implementation policies are essential to improve the air quality of the Tabriz environment. Hence, information provided in this research can be used as a key step for city managers, policymakers, and health officials to reduce the health impacts of air pollution.

Background and Objective: Indoor air pollution in hospitals could be a serious health threat to the patients, medical staff, and visitors. In previous studies, the importance of paying attention to air quality during the Coronavirus pandemic has been proven. In this study, the effect of visiters' presence under normal conditions and the imposition of hospital restrictions at the time of pandemic on air quality and environmental parameters in a hospital has been evaluated.
Materials and Methods: Air sampling was carried out in Valiasr Hospital of Zanjan in two periods, September 2019 (morning and visiting hours) and during the pandemic in October 2020. All wards inside and the outside of the hospital were examined for air pollutants (PM_2.5, PM₁₀, NO₂, SO₂, CO₂) and environmental parameters (temperature, humidity, and sound levels).
Results: The results of this study showed that except for the sound levels, other pollutants are at an acceptable level. Particulate matter of different sizes in the air of the hospital has a correlation, often with an external source, and has been imported through construction activitie;. However, nitrogen dioxide concentration is dependent on urban traffic. Visiting hours are associated with an increase in the concentration of particulate matter and the sound levels. The pandemic had a positive effect in some wards, on some parameters and often improved the air quality due to the imposing strict health protocols.
Conclusion: This study showed that natural ventilation has a direct effect on the air quality inside of the hospital. It is also suggested that in wards where patients are sensitive or in the need of intensive care, restrictions on commuting and visitation be applied.

Background and Objective: Heavy metal (HM) pollution of settled dust on the interior surfaces of elementary schools may affect the health of young students; hence, the health risk of such pollution should be assessed. Therefore, the aims of this study were to measure the content of heavy metals in the settled dust in the indoor of elementary schools in Bandar Abbas and to assess the attributed health risks.
Materials and Methods: In this study, dust samples were collected from the interior surfaces of elementary schools in Bandar Abbas. Settled dust samples were digested using aqua regia solution and then their metals contents were measured using ICP-OES. To assess the health risk attributed to this pollution, daily intake doses through ingestion, inhalation and skin absorption routes were estimated. Then, non-carcinogenic and carcinogenic risks were calculated considering the daily intake doses and toxicity factors.
Results: The average concentrations of arsenic, cadmium, cobalt, chromium, nickel and lead in settled dust were 5.45, 0.58, 11.44, 69.72, 83.95 and 66.72 mg/kg, respectively. The non-carcinogenic risk level for all metals was below threshold, while the carcinogenic risk level for arsenic (2.18×10^-6) exceeded the threshold.
Conclusion: This study showed that the settled dust in elementary schools of Bandar Abbas is polluted with various levels of heavy metals. Health risk assessment showed that the exposure to dust containing heavy metals in the elementary schools of Bandar Abbas does not pose significant non-carcinogenic risk, but the carcinogenic risk of As exceeded the threshold limit and should be considered.

Background and Objective: Bioaerosols as small particles enter the body by inhalation and lead to respiratory diseases based on type, concentration, and exposure time. In sensitive workplaces such as medical centers, it is necessary to pay attention to the type and population of these pollutants and the possibility of nosocomial infections. In the present study, the population and type of bioaerosols (bacteria and fungi) in the air of different hospital wards under normal conditions, visiting hours, and Covid-19 pandemic was evaluated.
Materials and Methods: Air sampling was carried out in different wards and ambient air of Valiasr Hospital of Zanjan during September 2019 (morning and visiting hours) and October 2020 (Corona pandemic) using an air sampling pump (Flite 3- SKC Ltd) with a flow of 14.1 L/min and then cultured in Sabaroud dextrose agar and nutrient agar.
Results: The results showed that air pollution in wards such as infectious diseases and clinics in both periods was more than other wards. The microbial density during visiting hours (before the coronavirus outbreak) was almost 30% higher than normal conditions. In October 2020, due to the coronavirus outbreak and reduced traffic, microbial air pollution in the hospital decreased. In both periods of study, the frequency of gram-positive bacteria, especially Staphylococcus species (49%) was higher than other bacteria and among fungal species the frequency of Aspergillus (47%) was higher than others.
Conclusion: This study showed that traffic restrictions caused by the coronavirus pandemic reduce microbial density in hospital space and this achievement can be used in the future with the aim of improving air quality and controlling nosocomial infections.
 

Background and Objective: Among greenhouse gases, CO₂ has a crucial role; thus, its impact on health indicators such as life expectancy is of great importance. Hence, one of the most important challenges in the health sector has been the impact of the environmental pollutants emission, namely CO₂, on life expectancy of men and women.
Materials and Methods: This is a descriptive-analytical and applied design with the health economics approach. The present paper examined the impact of pollutant emissions, namely CO₂, per capita income, death rate and birth rate, separately on Iranians’ life expectancy. This analysis was conducted using Quantile regression with EViews10 software during the period 1960 - 2019. In this study, first, the impact of pollutant emissions on life expectancy of all Iranians was calculated. Then, the impact of CO₂ on life expectancy of Iranian men and women in different quantiles was estimated.
Results: The results confirm the impact of carbon dioxide emissions per capita on total life expectancy was -0.133 and the impact of this pollutant emission on life expectancy obtained -0.170 and -0.127 for men and women, respectively. Both effects were estimated as negative and significant. This effect on life expectancy of men was 0.43% higher than that of women. Furthermore, the impact of death on life expectancy was negative, while the effect of per capita income on life expectancy was positive. Also, birth rate had a positive impact on women's life expectancy, whereas, it showed a negative impact on men.
Conclusion: The study revealed that CO₂ emissions had a negative impact on total life expectancy of both men and women. Thus, in order to increase life expectancy in Iran, pollutants emission, namely CO₂, should be controlled. These results can be a good guide to decision makers and macro-policy makers in Iran to control environmental pollutants to increase life expectancy.
 

Background and Objective: The city of Tehran is always exposed to adverse consequences due to the establishment of various sources of heavy metals. Therefore, the purpose of this study is to identify the types of heavy metals in airborne particles and the origin of heavy metals in the 21st district of Tehran.
Materials and Methods: According to the EPA standard, 5 stations from District 21 of Tehran were selected for sampling. Using the ASTM D4096 method and using a high volume sampling pump, 50 samples of total airborne particles were collected. The samples were transferred to the laboratory and the concentration of heavy metals was measured by ICP-OES. The UNMIX source model was used to identify heavy metal sources.
Results: The average concentration of heavy metals in 1400 is a decreasing trend including Li according to the concentration of heavy metals in the air in the SPECIATE database, the role of light vehicle sources was 47 percent 34 percent on the street and 18 percent at the airport.
Conclusion: The source of light vehicles exhibited the highest share of emissions and the element aluminum showed the highest concentration among heavy metals in Region 21. Therefore, the UNMIX source model can correctly identify index elements and priority sources for contaminant control.
 

Background and Objective: Toluene is one of the most important volatile organic compounds that threaten human health and introduce many environmental problems. Therefore, the present study aims to determine the performance of a biofilter based on pine cones/compost to remove toluene vapors from polluted air streams.
Materials and Methods: In this research, a biofilter with a volume of 19.468 L was designed and built. The biofilter bed consisted of two parts 26 cm in height and packed with a mixture of compost and pine cones in 1:1 volumetric ratio. After inoculating the bed with sludge from a municipal wastewater treatment plant and making it compatible with toluene, the performance of the biofilter in different parts of the bed was investigated at the inlet toluene concentrations of 2.5-5.5 g/m³ and Empty Bed Retention Times (EBRTs) of 1.3, 1.7, and 2.43 min. Also, the results were analyzed statistically.
Results: At EBRT of 2.43 min and different inlet toluene concentrations of 2.5-5.5 g/m³, the removal efficiency reached 100 percent. Also, the removal efficiency decreased with the reduction of EBRT. The results showed that removal efficiency was higher in the first part of the biofilter bed relate to the second part. At an inlet toluene concentration of 2.62 g/m³ and EBRT of 1.7 min, the maximum elimination capacity (EC_max) of 2.74 g/m³.min was obtained.
Conclusion: In all experimental conditions the outlet concentration of pine-cone/compost biofilter was below the WHO standard (260 µg/m³). Also, the high elimination capacity of biofilter verified its capability toward toluene removal from polluted gas streams.

Background and Objective: Today, oil and gas industries are important resources for obtaining energy and income. During the production of oil and gas, very complex compounds that include organic and inorganic substances, petroleum hydrocarbons and aromatic and aliphatic compounds are transferred to the environment. benzene, toluene, ethylbenzene and xylenes, which are called BTEX for short, are very important monoaromatic pollutants. Therefore, the present study was conducted to investigate the effect of exposure to BTEX on some clinical factors of the exposed people in the oil warehouse and office workers in Kermanshah National Oil Products Distribution Company.
Materials and Methods: This cross-sectional study was conducted in 2018. The samples of this study include the personnel working in the oil warehouse and the office staff of the National Oil Products Distribution Company in Kermanshah. After completing the demographic information of the participants in terms of the inclusion criteria and after collecting the results of the physiological tests of the employees, SPSS19 software was used for statistical analysis.
Results: The results of the present study showed that the spirometric indices decreased in the workers exposed to BTEX compounds, but it was not statistically significant. Also, the number of red blood cells (6.73%) was significantly lower in non-administrative employees, as well as red white blood cells (6.61%), SGOT (10.14%) and SGPT (5.09%) in non-administrative employees. It has been more.
Conclusion: The number of platelets was higher in office workers. Considering the dangers of BTEX pollution for human health, it is recommended to use preventive measures such as using a special mask and a shift work system.
 

Background and Objective: Various models have been developed to predict methane generation and emissions from landfills. Due to their simplicity, the minimum number of required data, and the accuracy of the outputs, First-order decay are the most common models to predict methane generation in landfill,. Three important parameters in modeling landfill gas generation using a first-order model are the total weight of waste buried in the landfill, the methane generation potential, and the methane generation rate constant. The purpose of this research was to accurately estimate the parameters of the first-order model and to optimize it for estimating methane generation in the landfill and also to develop the ILGAM software.
Materials and Methods: ILGAM model consists of two submodels: 1) the gas generation sub-model and 2) the methane oxidation sub-model. The methane oxidation sub-model is based on the MOT model. The gas generation sub-model is based on a first-order equation with an emphasis on the contribution of the aerobic process in the estimation of the ultimate methane potential of waste. The parameters of the equation were modeled using the latest available results in the literature. To evaluate the model, the actual methane emission and methane oxidation were measured in the Karaj landfill. The results of the model, along with a few common models, were compared with actual data obtained from the Karaj landfill.
Results: The ILGAM model predicted the gas emission from the Karaj landfill with an error of 5.8%. In contrast, LandGem, IPCC and CLEEN models predicted the methane gas emission from the Karaj landfill with an error of 74.4%, 40.2%, and 27.1%, respectively.
Conclusion: When compared to other models, the ILGAM model estimated the closest values to actual measurements for methane emission and methane oxidation in the Karaj landfill.  Owing to its user-friend Graphical User Interface (GUI), the model can be easily executed in a wide range of landfills by entering a few easy-to-measure data in the field.
 

Background and Objective: Particulate matter is an important air pollutant in urban areas with unknown effects on the fetus. The present study investigated the effect of PM_2.5 concentration on the level of liver enzymes in the neonate born in Isfahan city, one of the most polluted cities in Iran was investigated.
Materials and Methods: This case study was conducted between March 2019 to September 2020 in Isfahan. Blood samples were collected from the umbilical cord of 200 newborns to measure the level of liver enzymes from their blood serum using quantitative diagnostic kits and the spectrophotometry method. Seasonal distribution of PM_2.5 concentrations was estimated using the data of monitoring stations; thus, modeled and used to measure their correlations with liver enzyme levels at trimester in buffers of 500, 1000, and 2000 meters.
Results: The mean levels of liver enzymes were 38.42 (AST), 10.09 (ALT), 407 (ALP), and 152 (GGT) IU/L. Spring and fall with PM_2.5 concentrations of 24.35 and 35.35 and μg/m³ had the lowest and highest levels, respectively. Enzyme levels within the third trimester and the whole period of pregnancy in the 2000-m buffers had the highest correlation coefficient, which indicates the effect of high PM_2.5 concentrations on neonatal liver function, especially in late pregnancy.
Conclusion: Proximity to particulate matter sources in cities will increase the likelihood of elevated neonatal liver enzymes during the fetal period which is higher and more effective in late pregnancy.
 

Background and Objective: In this research, considering the importance of the adverse effects of the Covid-19 disease and identifying the environmental factors involved in its outbreak, the effects of environmental factors and compliance with health guidelines on outbreak and mortality of Covid-19 have been evaluated.
Materials and Methods: This research was a descriptive-analytical study on confirmed patients with Covid-19 in Alborz province in 2019. In this study, outbreak rate and death due to Covid-19, compliance with health guidelines, air pollutants concentrations, air pollution indicators, and the meteorological conditions of Alborz province were daily collected for 2019. All data were analyzed in IBM SPSS Statistics v26 software with Pearson, Spearman, Kruskal-Wallis, one-way variance ANOVA analysis tests, and negative binomial regression statistical models.
Results: The results of the regression model showed that in the mortality rate due to Covid-19, the variables of average temperature(p=0.042), humidity(p=0.048), rate of Covid-19 infection(p=0.001), and compliance with health guidelines(p=0.007) are significant. However, in the model of the rate of infection with Covid-19, only compliance with health guidelines(p=0.001) was significant. Pearson's and Spearman's correlation coefficients for infection rate, compliance with health guidelines, wind speed, and concentrations of carbon monoxide, PM_2.5, and SO₂ with the death rate due to corona, were 0.575, -0.411, -0.206, 0.211, 0.114 and -0.158.
Conclusion: The results showed that in addition to compliance with health guidelines, some atmospheric factors and air pollutants also impact the rate of infection and mortality caused by Covid-19.
 

Background and Objective: Climate change and environmental pollutants affect the growth of plant species. These effects can be recognized in the tree growth rings. This study aimed to investigate the effects of the precipitation and temperature in four decades (1975-2015) and air pollutants in the last decade on the average growth of pine trees (Pinus eldarica).
Materials and Methods: The studied area is Chitgar Forest Park located in the northwest of Tehran city and the studied species is the forest pine (Pinus eldarica). The research method is descriptive, the required climatic information was obtained from Mehrabad meteorological station and sampling was done by disc cutting from 10 forest pine trees. After preparing the samples, the number and width of annual rings were counted and measured using binoculars and a measuring table. One-way analysis of variance (ANOVA) was used at a significance level of 5% to investigate the significant difference in growth width in four decades.
Results: The results show that there is no significant difference between average precipitation in four decades, while average temperature and average growth have significant differences (p < 0.05). The amount of growth based on the growth index has decreased during four decades, and this decrease is more significant and obvious in the fourth decade due to the increase of pollutants such as ozone (O₃) and nitrogen dioxide (NO₂).
Conclusion: In general, the growth of forest pine trees has decreased during forty years with the increase of average annual temperature, which excessive decrease in the fourth decade is caused by pollutants such as ozone and nitrogen dioxide. It is suggested to do more research on sensitive species planted in urban areas to better understand the effect of pollutants on the growth and development of trees.
 

Background and Objective: During the last few decades, heavy metal pollution in indoor dust has been widely studied; While, the quality of the environment inside the cars has not been considered enough. Therefore, the specific objectives of this study generally include investigating the levels of selected heavy metals in the dust of private cars collected from Ahvaz city, as well as evaluating the health risk of carcinogenesis and exposure to the dust inside these cars through ingestion, inhalation, and skin absorption.
Materials and Methods: 10 cars were selected for this study. The condition of choosing the cars was not to wash the car for a week. Then, samples were collected and coded from the dust of the air conditioner filter and the cabin of each car. To determine the composition of heavy metals, spectroscopic analysis (ICP) was performed on the samples.
Results: The study of non-carcinogenic risk index (HI) in the present study indicates that the values of more than 1 and the health risk is high. The sequence of HI index values for heavy metals was obtained as  Pb>Cu>Cr> Fe> Zn> Cd> Ni. Evaluated risks from different pathways in children was HQ_ing < HQ_inhder while in adults follows HQ_ingder< HQ_inh process. Additionally, the values of enrichment factor of the studied samples showed the maximum and minimum values for Cu (4.3) and Ni (8.3), the maximum and minimum geoaccumulation index for Fe (12.75) and Ni (1.9) and the amount of integrated pollution and pollution index were estimated to be 1.34+E27 and 2.07+E9, respectively, indicating the average range for the studied heavy metals.
Conclusion: According to this study, the risk of non-carcinogenic risk of heavy metals (except Fe and Cu) for children is estimated to be higher than that of adults. Furthermore, the investigation of the CR index for the three carcinogenic heavy metals (cadmium, chromium, and arsenic) has exceeded the safe level, which indicates ingestion and inhale as the target pathways for the worst adverse effects of heavy metals in children andadults, respectively. In the present study, the amount of heavy metals studied is more than the set standards. The results of the current study showedthe more enrichment of heavy metals in the car filter as compared with  the cabin.
 

Background and Objective: Given the concern about the presence of microplastics in the air and settled dust, and the lack of a standard approach for their detection, it is necessary to investigate the methods and techniques used to study this type of pollution in Iran. Therefore, this study aimed to systematically review the methods and techniques used for sampling, quantification, and characterization of microplastics in the air and settled dust in indoor and outdoor environments in Iran.
Materials and Methods: In this systematic review, the keywords Microplastic*, Air*, Atmosphere*, Dust, Indoor, Outdoor, Iran, and their corresponding Persian equivalents were searched until Dec 1, 2023, in Scopus, PubMed, Web of Science, Google Scholar, Magiran, and SID databases. Obtained articles from the databases were analyzed in order to find the eligible ones.
Results: Overall, 175 articles were found in the initial search, and after removing the duplicates and nonrelevant, 13 eligible articles were included in the study. In most of the studies, the samples were digested with H₂O₂, and the microplastics were mainly analyzed using a variety of microscopes and µRaman spectroscopy. The abundance of microplastics in the indoor environment was much higher than in the outdoor environment.
Conclusion: The results of this study showed that there is the required equipment for the sampling and analysis of microplastics in air and settled dust in Iran, and these pollutants have been detected in both indoor and outdoor environments.
 

Background and Objective: One of the largest sources of methane emissions is landfills, and various models have been developed to predict landfill methane production and emissions. The main goal of this research is to utilize the inverse Gaussian model to estimate g methane greenhouse gas emissions and model it using field data. This study introduces a simple method to estimate the amount of methane emissions based on ambient methane concentrations.
Materials and Methods: In this research, the methane emission rates from landfill were estimated for warm (July) and cold (February) seasons using a sampling campaign from 27 stations and standard inverse Gaussian dispersion equations. Monte Carlo simulation was also employed. To determine the model, an optimization-based method, along with inverse scattering modeling, was utilized to process surface emission monitoring data.
Results: The model results indicated during the cold (February) and warm (July) seasons, the methane emission rates were estimated at 1696.99 and 16.53 g/s, respectively. These findings confirm that the methane production and emission during the cold season were lower than in the warm season, likely due to reduced temperature and bacterial activity.
Conclusion: The method used in this study, the inverse Gaussian dispersion model, can be applied to estimate methane gas emission rates from other landfills. However, it necessitates the permanent recording of data and the use of daily or weekly averages in calculations to mitigate potential errors and enhance the accuracy of modeling.
 

Background and Objective: One of the major challenges in the calcium looping process is the loss of CO₂ capture capacity of calcium-based sorbents during consecutive cycles due to increased sintering mechanism. This article aims to improve the performance of carbonation conversion in different cycles by employing hydration and acidification methods.
Materials and Methods: Following the preparation of both  CaO-based and modified sorbents, scanning electron microscopy, X-ray diffraction, and Brunauer-Emmett-Teller analyses were employed to verify the proper preparation of the sorbents and examine their structures. Subsequently, the adsorption performance of different samples was assessed using a thermogravimetric analyzer device .
Results: The results of the carbonation reaction showed that the effective conversion rates for the raw and modified sorbents, employing acidification and hydration methods, at the end of the first cycle were 75%, 86%, and 73%, respectively. By the twentieth cycle, these rates decreased to 24%, 38%, and 26%, respectively. This decline indicates an improvement in the sorbent's capture capacity, attributed to the formation of calcium acetate, resulting in a more stable and porous structure. The findings from utilizing raw limestone sorbents and their modified versions through acidification and hydration techniques demonstrated a decrease in sorbent capture capacity by 69, 58, and 67% across twenty cycles. This highlights the enhanced sorbent stability achieved with the acidification method.
Conclusion: Based on obtained results, acidification method can be considered as one of the most efficient approaches for improving the performance of calcium oxide sorbents.
 

Background and Objective: The air quality index (AQI) does not account the interaction of multiple pollutants, meaning the high concentration and health risk of one pollutant may amplify the effects of others. The main aim of this study was to characterize the ambient air quality of Arak by assessing the combined effects and health risks associated with criteria air pollutants.
Materials and Methods: This study evaluated the ambient air quality of Arak for the year 1401 on the Persian Calendar, using the concentrations of criteria air pollutants averaged over appropriate timeframes. Additionally, the AQI, aggregate air quality index (AAQI), and health risk-based air quality index (HAQI) were calculated.
Results: Findings showed that the 1-hour concentrations of NO₂, SO₂, PM₁₀, and PM_2.5 exceeded national standards in 0.05%, 0.2%, 12.1%, and 35.5% of hours, respectively. The AQI, AAQI and HAQI values were above 100 in 54.4%, 77.3%, and 56.2% of hours, respectively. PM_2.5 was the major pollutant in over 99% of cases.
Conclusion: The results indicated that AAQI and HAQI, in comparison to AQI, characterized the air quality as more polluted. This stricter assessment by AAQI and HAQI may encourage more precautionary measures by authorities and the public. Thus, it is recommended that the decision-makers in Iran’s air quality monitoring in consider adopting these indices.
 

Background and Objective: The adverse health effects of polycyclic aromatic hydrocarbons (PAHs) have received significant attention in recent years. This study aimed to measure the concentration of PAHs associated with fine particles and assess the health risks posed by these compounds.
Materials and Methods: A total of 38 air samples were collected from the central part of Isfahan city using a particle sampler equipped with an inlet to capture particles smaller than 2.5 µm (PM_2.5). The samples were analyzed using GC-MS, and molecular ratios were used to identify potential sources of PAHs. Additionally, a Monte Carlo simulation was employed to perform a probabilistic risk assessment of carcinogenic and non-carcinogenic effects of PAHs for two groups:  children and adults.
Results: Out of the 16 priority PAH compounds, seven compounds were identified, with average concentrations ranging from 0.003 to 17.8 ng/m³. Molecular ratios indicated that pyrogenic sources were the main contributors to PAHs in the air. The median carcinogenic risk for children and adults was estimated to be 3.1×10^-8 and 5.99×10^-8, respectively. The median non-carcinogenic risk for PAH compounds was estimated at 3.08×10^-1.
Conclusion: The probabilistic risk assessment revealed that the PAHs concentrations associated with fine particles do not pose a significant risk to exposed individuals. However, it is important to note that this study focused solely on the risk assessment of PAHs associated with fine particles. A comprehensive risk assessment of all PAHs present in the atmosphere is, therefore, recommended.