Introduction: The aim of this study was to investigate the concentrations of PM₁₀, PM_2.5, O₃, NO₂, SO₂, and CO in Tehran during March 2014-March 2018, and evaluate the effects of holidays and meteorological parameters on the air pollution levels.
Materials and methods: Hourly concentrations of PM₁₀, PM_2.5, O₃, NO₂, SO₂, and CO in different air quality monitors of Tehran were acquired. The data from each air quality monitored were validated, and only high-quality monitors were included in this study.
Results: The 4-year averages of PM₁₀, PM_2.5, O₃, NO₂, SO₂, and CO concentrations were 88.74 (μg/m³), 31.02 (μg/m³), 34.87 (ppb), 71.01 (ppb), 20.04 (ppb), and 3.78 (ppm), respectively. Higher concentrations of PM10 and O3 were observed during summer. In case of PM_2.5 and CO, autumn and winter concentrations were higher than those in springer and summer. Lower concentrations of PM10 and NO₂ in Fridays were observed comparing to other days of week. Ozone had high concentrations in Fridays as the weekend in Iran. Except for O₃, all of the pollutants had higher concentrations in the working days, comparing to those in any type of vacation days. Concentrations of all pollutants rather that SO₂ and O₃ in Nowruz holidays were statistically lower than those in the working days. By controlling for the effects of meteorological variables, our results showed that the air pollution control policies and actions have been not effective for particulate matter.
Conclusion: These results determines the time periods in which the concentrations of criteria air pollutants are high. This can be very useful for announcing alarms for citizens, and designing the air pollution control plans. In addition, more effective actions should be designed and implemented for reducing ambient levels of particulate matter.

Introduction: Exposure to toxic components in indoor PM is associated with a wide spectrum of adverse respiratory and cardiovascular health effects. The fine PM pollution in ambient air is currently a major health concern in Iran and is driving increasing research interest. Due to air pollution in Tehran metropolitan, it is necessary to study the concentration and size distribution of particles inside and outside the building.
Materials and methods: Hence, for this study, concentration and size distribution of particles matter was calculated with diameters of PM_≤0.4, PM_0.4-0.7, PM_0.7-1.1, PM_1.1-2.1, PM_2.1-3.3, PM_3.3-4.7, PM_4.7-7, PM_7-11, PM_≥11 and TSP during two seasons in the lab building in the Tehran. Measurements on the aerodynamic size of atmospheric aerosols carried with Anderson type 1-ACFM Cascade Impactor with six-stage. The length of each collection period was about 24 h.
Results: The results show that the effect of outdoor air pollution on the concentration of particles in the indoor environment is significant. According to these results, the lowest value is for particles with a diameter greater than 11 μm. the highest value of this ratio is dedicated to PM≤0.4 and with the increase of the aerodynamic diameter of the particles, the I/O decreases as well. A similar trend was recorded for concentration of TSP. The highest difference in the concentration of TSP in indoor and outdoor was 60.25 and 188.36 μg/m³, respectively.
Conclusion: This effect is due to factors such as the lack of standard ventilation, old doors and windows and the life of the building.

Introduction: Today, due to the discussion of carbon management as well as the reduction of greenhouse gases and national and international commitments involved in this regard such as the Six Development Plan (2016-2020) and climate change convention it, is necessary to calculate and manage all industrial processes that lead to the greenhouse gases emission. Methane is the main ingredient of natural gas, which its potential for global warming is 25 times more than carbon dioxide. Approximately a third of these emissions are in the different sections of oil production and processing, transferring and storing of natural gas.
Materials and methods: The present study has been done to calculate the amount of methane emission to the atmosphere by startup of Siemens gas compressors in Iran gas transmission operation district 2. In this study, operational information of 25 Siemens gas Turbo compressors related to six gas transmission stations collected and with modeling conditions in PHAST, the amount of methane emission has been determined.
Results: According to the obtained data, in 2018 this district has released 140/870 tons of methane gas to the atmosphere due to the above-mentioned process. The methane emission factor for Type C compressor is 241/15 kg, for type D compressor is 341/35 kg and this factor for type E compressor is 375/48 kg.
Conclusion: The release rate obtained for each type of the C, D and E compressors can be used to calculate the emissions of all SIEMENS 10MV2A gas compressors of the same model in Iran.

Introduction: Dust is a natural process in desert areas, which is caused by the effect of strong winds on the surface of the soil. The aim of this study is to investigate the conditions of the formation and expanding the dust storm formed in Iraq to the Khuzestan province in February, 2017.
Materials and methods: The synoptic analysis was conducted using meteorological parameters from ERA-interim and observation data from the Ahwaz station. In addition, the EUMETSAT satellite, the DREAM and the HYSPLIT model output were used.
Results: As the results show, regarding to the storm, dust in low- pressure area located over Iran is expanded toward the west associated with the tough 500 hPa . With the formation of the high-pressure area in Syria, a pressure gradient is formed in Iraq resulting the northwest wind with the wind speed of 30 knots s (15 m/s) in 925 hPa. These conditions have led to transport the dust from Iraq toward southwest of Iran. A jet stream is formed 12 h before entering the dust from Iraq to Iran, at 900 hPa. The HYSPLIT model predicts the particle’s motion along the northwest winds, and is matched with the wind field in synoptic structure.
Conclusion: According to this study, the most important factors in dust transport to the Persian Gulf are geographic location of the low- and high-pressure area and the formed northwest winds in Iraq.

Introduction: Due to increasing the population of cities and the physical-spatial expansion of the cities, vehicles are being used progressively, which has caused many problems for the cities including traffic increase, chaos in finding urban parking lots, increase of environmental pollution, decrease of citizens’ satisfaction, and so on. Among the many urban problems, parking lot is one of the issues that has been heavily debated in recent years. The lack of sufficient number of parking lots, on the one hand, and the related disorder and management problems, on the other hand, have led to a range of managerial and environmental problems. Meanwhile, one of the paradigms that has focused on this issue in recent years is smart city paradigm, which has offered the smart parking. This paradigm believes that parking, as a part of the city’s space, can be smart and can help urban management.
Materials and methods: This is an applied research in terms of purpose and a descriptive-analytical research in terms of nature. The required data were collected using documentary and field studies and SWOT method was used to analyze the data.
Results: This study was conducted to evaluate and investigate the role of smart parking in increasing the efficiency of urban management and its impact on reducing air pollution.
Conclusion: Finally, the conclusion of the research have led to key strategies for achieving the research goal.

Introduction: The wide range of studies on air pollution requires accurate and reliable datasets. However, due to many reasons, the measured concentrations may be incomplete or biased. The development of an easy-to-use and reproducible exposure assessment method is required for researchers. Therefore, in this article, we describe and present a series of codes written in R Programming Language for data handling, validating and averaging of PM10, PM2.5, and O3 datasets.
Findings: These codes can be used in any types of air pollution studies that seek for PM and ozone concentrations that are indicator of real concentrations. We used and combined criteria from several guidelines proposed by US EPA and APHEKOM project to obtain an acceptable methodology. Separate .csv files for PM10, PM2.5 and O3 should be prepared as input file. After the file was imported to the R Programming software, first, negative and zero values of concentrations within all the dataset will be removed. Then, only monitors will be selected that have at least 75% of hourly concentrations. Then, 24-h averages and daily maximum of 8-h moving averages will be calculated for PM and ozone, respectively. For output, the codes create two different sets of data. One contains the hourly concentrations of the interest pollutant (PM10, PM2.5, or O3) in valid stations and their average at city level. Another is the final 24-h averages of city for PM10 and PM2.5 or the final daily maximum 8-h averages of city for O3.
Conclusion: These validated codes use a reliable and valid methodology, and eliminate the possibility of wrong or mistaken data handling and averaging. The use of these codes are free and without any limitation, only after the citation to this article.