Vol 4 No 2 (2019): Spring 2019

Original Research

  • XML | PDF | downloads: 193 | views: 519 | pages: 81-86

    Introduction: This study aimed to calculate and evaluate air quality index (AQI) in Tehran according to the EPA’s instruction, and evaluate the obtained values.
    Materials and methods: The study period included three years of 2013, 2015, and 2017 within the six-year period of 2013-2017. The concentrations of six studied pollutants were acquired from Department of Environment (DE) and Air Quality Control Company of Tehran (AQCC). EPA’s method was applied to calculate AQI values during the study period, selecting the highest AQI value among all of the pollutants and monitors.
    Results: The three-year average of AQI was about 147. During all the three years, the air quality had never been in a “good” condition (AQI<50). About 92%, 91%, 87% of AQIs indicated the conditions unhealthy for sensitive groups (100<AQI<150) or unhealthy for all groups (150<AQI<200). PM2.5 accounted for most of the AQI values in Tehran, followed by NO2 and O3. Evaluating the histogram of AQI values indicated a strange form of distribution, showing a decline in the 100-150 range and a sudden increase just after AQIs higher than 150.
    Conclusion: This study indicated that governmental organizations should follow EPA’s instruction for AQI calculations to avoid underestimation of air pollution, and broadcast accurate and reliable AQIs to public. To determine the reason for the abnormal distribution of AQI, further studies with longer study periods are required.

  • XML | PDF | downloads: 122 | views: 553 | pages: 87-98

    Introduction: The computational fluid dynamics (CFD) simulation of three-dimensional wire-plate electrostatic precipitator is performed in the present study.
    Materials and methods: The momentum equation, the electric potential equation and current continuity equation are solved by using ANSYS Fluent. The ion charge density at the corona is calculated iteratively using the Peek formula. The SIMPLE algorithm is used to treat the pressure-velocity coupling. The RNG k-ε model is used to describe turbulence.
    Results: The airflow keeps stable away from the first corona electrode. The distribution of the electric potential is dependent on the wire-plate distance and the wire-wire distance. The potential and ion charge density increase with the increase of the wire-plate distance. With the increase of wire-wire distance, the maximum electric field strength decreases whereas the maximum ionic charge density increases. The ion charge density near the second corona electrode is relatively small. A small wire-wire distance will make the electric field concentrated around the wires.
    Conclusion: According to this study, the wire-wire distance and the wire-plate distance have great effect on the distribution of ion charge density and electric field strength.

  • XML | PDF | downloads: 124 | views: 462 | pages: 99-108

    Introduction: This study aimed to evaluate exposure to PM10 related to traffic and drying Lake Urmia and its effects on human health in north-west of Iran.
    Materials and methods: Sampling and analysis was done during 2015 to 2016 using AirQ 2.2.3.
    Results: The annual mean of PM10 concentrations were 106 μg/m3, which was too higher than 20 μg/m3 recommended by WHO guideline. The maximum seasonal mean concentration of PM10 was observed in winter (138 μg/m3). Attributable proportion (AP) due to exposure to PM10 were estimated 5.487% (95%CI: 3.726-7.185%) of non-accidental mortality cases, 8.011% (95%CI; 4.615-11.174%) of cardiovascular mortality, and 11.174% (95%CI; 4.615-16.215%) of respiratory mortality, for Urmia inhabitants. With every 10 μg/m3 increase in PM10 concentrations, relative risk (RR) for total mortality increased by 0.6%.
    Conclusion: The total cases numbers for hospital admission due to cardiovascular and respiratory diseases in central RR were 257 and 666 cases, respectively. Since incineration fossil fuel, the salty dust storms caused by climate change and drying Urmia Lake is natural, therefore, increasing green space and extensive activities such as desertification are need to control this phenomenon that is extremely challenging.

  • XML | PDF | downloads: 88 | views: 395 | pages: 109-120

    Introduction: Air pollution, due to its harmful effects especially on human health, is one of the major problems of industrial cities and metropolises, including Tehran. Therefore, recognizing the atmospheric conditions that lead to the accumulation of the pollutants can help decision-maker organizations.
    Materials and methods: In this study, based on the intensity and persistency of the air pollution in the period of 1389-1397 and according to the season of its occurrence, 47 air pollution incidents in Tehran were identified and studied from synoptic perspective. Spatial (T-Mode) principal component analysis was applied to 500-hpa geopotential height data of these events to classify the synoptic patterns which make the city prone to intensification of pollution in different seasons.
    Results: The results indicate three different synoptic patterns leading to an increase in the potential of pollution of Tehran. In these patterns, the main pollutant is the airborne particulate matter (PM2.5 and PM10). Accordingly, the first pattern with percentage frequency of 62% occurs in the fall and winter. In this pattern, the presence of Siberian high pressure, along with the mid-tropospheric ridge is obvious. Two other patterns are active in the late spring and summer (related to Indian monsoon in the southeast of Iran) and spring and autumn (related to dynamic low-pressure in Iraq and the west of Iran), respectively.
    Conclusion: Classifying of the data of polluted days during recent eight years for Tehran results in three synoptic patterns related to different seasons. This information can help better managing of urban activities.

  • XML | PDF | downloads: 112 | views: 500 | pages: 121-132

    Introduction: The purpose of the current study was to investigate the ambient concentration levels of ground-level ozone, nitrogen dioxide, and sulfur dioxide with temporal variations and to determine the risk of exposure to their pollutant on public people living in this area.
    Materials and Methods: In the present study, GLO, NOx and SO2 concentrations were monitored using an ambient analyzer during the period of April to September 2018.
    Results: The results of the present study show that the average of SO2, NO2 and GLO concentrations in the INZ location was found to be about 8.9, 7.2 and 11.9 times the average value in the SHV location and about 4.8, 5.3 and 2.9 times the average value in the CMC location, respectively. The average values of SO2 and NO2 concentrations in the INZ varied from 97.2 to 128.1 μg/m3 in the evening hours and from 50.2 to 62.3 μg/m3 in the morning hours respectively. Also, the lowest concentration of NO2 was observed during afternoon hours when GLO showed a peak. The maximum pikes of GLO concentration were observed at 13:00 PM with 249.3 μg/m3. Results of human health risk assessment indicated acceptable risk (hazard quotient (HQ) values ˂ 1) for non-carcinogenic adverse health effect.
    Conclusions: The findings in the present study can be useful in developing control-based strategies for primary pollutant emissions, and also GLO formation, improve air quality and reducing possible risks on human health. Policymakers should enforce the limits on the release of pollutants into the atmosphere in the study area by strengthening existing legislation.

  • XML | PDF | downloads: 94 | views: 444 | pages: 133-146

    Introduction: Many countries in the arid and semi-arid regions of the world encounter dust storms phenomenon, that is one of the meteorological problems leading to daily life disturbances, financial losses, public health risks and the destructive environmental impacts.
    Materials and methods: Although the dust storm is historically recorded as an old event in some provinces of Iran, nowadays it becomes a new event in the other provinces such as Ilam in the west of Iran. Dust storms have been remarkably increased since 2007 in a period of 20 years (1997-2017) of daily frequency of dust storms in Ilam station. The dust storm is mostly observed in Ilam city (center of Ilam province) in 2011, after the years of rainfall deficiency.
    Results: After statiscal investigation of dust storms in Ilam province and factors affecting its formation, the dust storm from 3nd to 6th July 2016 are studied that reduced visibility so much in West and SW of Iran. On the of 3rd- 4th of July of the same year, the intensity of the dust storm was so high that made the visibility decresses severely in Ilam city. The source of this dust storm was the eastern areas of Syria and central Iraq. This fact also appeared in the satellite images and in the output of HYSPLIT MODEL. The output of WRF-Chem Model clearly shows the dust mass over East-Syria, Central and East Iraq and West and SW Iran.
    Conclusion: Model outputs in intensity of surface dust concentration of MACC-ECMWF, NASA-GEOS, NCEP-NGAC, NMMB-BSC, and BSC-DREAM8b models are compared to the observation of the aerosol concentration in Ilam city and results show that NASA-GEOS model has better performance, based on the results compared to the other models.
    In display of dust dispertion on Iran, the middle of all models is more compatible with reality.