Tehran, the capital city of Iran, is one of the largest cities in the world. It extends over an area of approximately 2,300 square kilometers and has a population of more than 10 million people. The city is suffering from atmospheric pollution arising from the rapid urbanization during the last 3 to 4 decades. The city will develop towards the west to Karaj, and large volumes of traffic will be going east-west by the year 2015. With more than 2 million vehicles in Tehran, most of which are more than 20 years old, traffic is the major source of air pollution in Tehran. The city of Tehran has a significant air pollution problem and suspended particulate matter (SPM) appears to rank high on the list pollutants. The monthly average of PM-10 in Tehran is high in autumn and low in spring. Maximum average value observed in September is over 370 microg/m(3); the minimum in March (102 microg/m(3)) and early April (65 microg/m(3)). The diurnal variation PM-10 concentration have been studied.
Polycyclic aromatic hydrocarbons (PAHs) are toxic pollutants released by various urban combustion sources. Benzo[a]pyrene (BaP) is a representative member of the class of PAHs. Health risk assessment associated with inhalatory PAHs uptake is often estimated on the basis of the BaP concentrations in air. Atmospheric particulate PAHs concentrations were measured at five locations in Tehran, Iran. Sixteen PAHs were extracted from the airborne particles and analyzed by HPLC. Total PAHs concentrations (16 compounds) at five station Arjanteen, Enghelab, Azadi, Bahman, Haft Houz were respectively, 70.2, 96.5, 130, 79.1, 44.1 ng/m(3). The information obtain from the present study indicated that mean of human carcinogens are: benzo[a]antheracene (0.17-4.76 ng/m(3)), chrysene (1.74-3.62 ng/m(3)), benzo[b]fluoranthene (0-5.25 ng/m(3)), benzo[k]fluoranthene (0.32-1.72 ng/m(3)), benzo[a]pyrene (1.41-3.82 ng/m(3)), dibenzo[a,h]anthracene (0.33-2.13 ng/m(3)), and indeno[1,2,3-cd]pyrene (0.25-11.08 ng/m(3)). The development and the establishment of a toxicity equivalency factor (TEF) are used in the assessment of mixtures containing PAHs. The contribution of the carcinogenic potency of BaP alone is in the range of 49.6-76.3% of the total carcinogenic activity. The annual number of lung cancer cases (persons per million) among Tehran residents (population = 10 millions) attributable to these carcinogenic PAHs compounds in 2005 was estimated at 58 persons per million. In Tehran urban areas vehicular emission are the primary contributor to PAHs concentrations, with additional local contributors like industrials emissions.
The objective of this work was to evaluate the indoor-outdoor particle size distribution in elementary schools located in central parts of Tehran and to evaluate those parameters that could be influencing the indoor particles concentrations in the classrooms. Concentrations of particles including PM10, PM2.5 and PM1.0, as some of the main air pollutants in Tehran, were measured in the schools, during winter 2009. It was found that the average indoor concentrations of PM10, PM2.5 and PM1.0 were 274 µg/m3, 42 µg/m3 and 19 µg/m3, respectively, while the outdoor concentrations for these particles were 140 µg/m3, 38 µg/m3 and 22 µg/m3, respectively. The main factors influencing indoor particle pollution were found to be the outdoor concentrations of the particles and the physical activity of the students, but other factors such as the differences between indoor and outdoor temperatures, class size dimensions and types of boards in the classrooms had negligible effects.
Tehran, the capital city of Iran, is an important industrial and commercial center. This city is one of the worst cities in the world in terms of air pollution, which is mostly due to mobile sources rather than stationary sources. Particulate matter (PM), which is a complex mixture of extremely small particles and liquid droplets, is considered as an important source of air pollution in Tehran. In this study, our objective was to study PM(10), PM(2.5), and PM(1.0) mass and number concentrations and find the correlations of these two parameters in the west-central parts of Tehran during two consecutive warm and cold seasons. The particles collected from five stations were analyzed for their mass and number simultaneously by a laser-based Grimm dust monitor. In general, it was found that the accumulation of the PM in this region is more in the cold season. PM(10) mass concentration increases almost twofold and PM(2.5) and PM(1.0) almost three times in this season. The mean number concentration of the particles (0.3-20 microm) was found to be almost 4.8 times in the cold season. It was also noticed that the average dimensions of the particles decrease in that season.
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