|
انتخاب زبان: فارسی English

مقالات علمی منتشر شده

Investigating the influence of traffic emission reduction plans on Tehran air quality using WRF/CAMx modeling tools

Abstract: Due to its dangerously high level of pollutants, Tehran air quality is a serious concern. Several immediate and emergency solutions have been pursued to mitigate the problem in the short term. Most of the solutions are based on traffic-restriction schemes that pose challenges to citizens’ mobility. As part of such policies, the central part of the city has been converted into a traffic restricted zone (TRZ) in which vehicles are allowed to enter only on certain days of the week based on their license plate number. The purpose of this study was to investigate the effectiveness of such policies on reducing the concentration of various pollutants by using advanced air quality modeling approach. First, the pollutant emissions were calculated using the International Vehicle Emissions (IVE) model, and the results were used in the WRF/CAMx modeling system to investigate the effects of traffic restriction enforcement policy on air quality and pollutants dispersion over Tehran. Measured data at monitoring sites were used to benchmark performance of the modeling system. The results showed satisfactory performance of both models in predicting meteorological parameters and concentration of pollutants. While emission input data was reduced by 40% in the TRZ, the maximum reduction in CO as a primary pollutant was approximately 20%, which is highly related to the traffic conditions. Results suggest that effectiveness of TRZ policies highly depends on the type of pollutant, meteorological conditions, and the location of the study area.

Land Use Regression Models for Alkylbenzenes in a Middle Eastern Megacity: Tehran Study of Exposure Prediction for Environmental Health Research (Tehran SEPEHR)

Abstract: Land use regression (LUR) has not been applied thus far to ambient alkylbenzenes in highly polluted megacities. We advanced LUR models for benzene, toluene, ethylbenzene, p-xylene, m-xylene, o-xylene (BTEX), and total BTEX using measurement based estimates of annual means at 179 sites in Tehran megacity, Iran. Overall, 520 predictors were evaluated, such as The Weather Research and Forecasting Model meteorology predictions, emission inventory, and several new others. The final models with R2 values ranging from 0.64 for p-xylene to 0.70 for benzene were mainly driven by traffic-related variables but the proximity to sewage treatment plants was present in all models indicating a major local source of alkylbenzenes not used in any previous study. We further found that large buffers are needed to explain annual mean concentrations of alkylbenzenes in complex situations of a megacity. About 83% of Tehran's surface had benzene concentrations above air quality standard of 5 μg/m3 set by European Union and Iranian Government. Toluene was the predominant alkylbenzene, and the most polluted area was the city center. Our analyses on differences between wealthier and poorer areas also showed somewhat higher concentrations for the latter. This is the largest LUR study to predict all BTEX species in a megacity.

Spatiotemporal description of BTEX volatile organic compounds in a Middle Eastern megacity: Tehran Study of Exposure Prediction for Environmental Health Research (Tehran SEPEHR)

  • Authors:Heresh Amini, Vahid Hosseini, Christian Schindler, Hossein Hassankhany, Masud Yunesian, Sarah B. Henderson, Nino Künzli
  • pdf icon مشاهده مقاله

Abstract: The spatiotemporal variability of ambient volatile organic compounds (VOCs) in Tehran, Iran, is not well understood. Here we present the design, methods, and results of the Tehran Study of Exposure Prediction for Environmental Health Research (Tehran SEPEHR) on ambient concentrations of benzene, toluene, ethylbenzene, p-xylene, m-xylene, o-xylene (BTEX), and total BTEX. To date, this is the largest study of its kind in a low- and middle-income country and one of the largest globally. We measured BTEX concentrations at five reference sites and 174 distributed sites identified by a cluster analytic method. Samples were taken over 25 consecutive 2-weeks at five reference sites (to be used for temporal adjustments) and over three 2-week campaigns in summer, winter, and spring at 174 distributed sites. The annual median (25 th e75 th percentile) for benzene, the most carcinogenic of the BTEX species, was 7.8 (6.3e9.9) m g/m 3 , and was higher than the national and European Union air quality standard of 5 m g/m 3 at approximately 90% of the measured sites. The estimated annual mean concentrations of BTEX were spatially highly correlated for all pollutants (Spearman rank coefficient 0.81e0.98). In general, concentrations and spatial variability were highest during the summer months, most likely due to fuel evaporation in hot weather. The annual median of benzene and total BTEX across the 35 sites in the Tehran regulatory monitoring network (7.7 and 56.8 m g/m 3 , respectively) did a reasonable job of approximating the additional 144 city-wide sites (7.9 and 58.7 m g/m 3 , respectively). The annual median concentrations of benzene and total BTEX within 300 m of gas stations were 9.1 and 67.3 m g/m 3 , respectively, and were higher than sites outside this buffer. We further found that airport did not affect annual BTEX concentrations of sites within 1 km. Overall, the observed ambient concentrations of toxic VOCs are a public health concern in Tehran.

Seasonal trends, chemical speciation and source apportionment of fine PM in Tehran

  • Authors:Mohammad Arhami, Vahid Hosseini, Maryam Zare Shahne, Mostafa Bigdeli, Alexandra Lai, James J. Schauer
  • pdf icon مشاهده مقاله

Abstract: Frequent air pollution episodes have been reported for Tehran, Iran, mainly because of critically high levels of fine particulate matter (PM 2.5 ). The composition and sources of these particles are poorly known, so this study aims to identify the major components and heavy metals in PM 2.5 along with their seasonal trends and associated sources. 24-hour PM 2.5 samples were collected at a main residential station every 6 days for a full year from February 2014 to February 2015. The samples were analyzed for ions, organic carbon (including water-soluble and insoluble portions), elemental carbon (EC), and all detectable elements. The dominant mass components, which were determined by means of chemical mass closure, were organic matter (35%), dust (25%), non-sea salt sulfate (11%), EC (9%), ammonium (5%), and nitrate (2%). Organic matter and EC together comprised 44% of fine PM on average (increased to >70% in the colder season), which reflects the significance of anthropogenic urban sources (i.e. vehicles). The contributions of different components varied considerably throughout the year, particularly the dust component that varied from 7% in the cold season to 56% in the hot and dry season. Principal component analyses were applied, resulting in 5 major source factors that explained 85% of the variance in fine PM. Factor 1, representing soil dust, explained 53%; Factor 2 denotes heavy metals mainly found in industrial sources and accounted for 18%; and rest of factors, mainly representing combustion sources, explained 14% of the variation. The levels of major heavy metals were further evaluated, and their trends showed considerable increases during cold seasons. The results of this study provide useful insight to fine PM in Tehran, which could help in identifying their health effects and sources, and also adopting effective control strategies.

Promoting Good Prenatal Health: Air Pollution and Pregnancy

Abstract: Some pollutants of concern are secondhand smoke, carbon monoxide, fumes from paint and household cleaners, particulate matter, and ozone. Women of child-bearing age, pregnant women, new mothers, families, and their health care providers should be aware of the potential hazards of outdoor and indoor air pollution to developing fetuses and small children. Research shows that prenatal exposure to pollutants can increase the risk of preterm delivery and low birth weight (LBW; less than 2,500 grams, or 5.5 pounds), which are public health challenges in the United States, as they contribute significantly to infant mortality and developmental disabilities. This fact sheet identifies some common environmental exposures and provides simple steps that health care providers can recommend to pregnant women and new mothers to avoid exposure.

Urban Air Pollution in Iran

Abstract: Urban air pollution is a major health risk in several large Iranian cities. Transportation, extensive use of fossil fuels, outdated urban fleets of gasoline and diesel vehicles, industrial sources within and close to the city boundaries and natural dust are major contributing factors. Starting with Tehran, emission inventories and mathematical air pollution models are being developed. Air quality is being monitored and reported to the public, though data availability and validity remain a challenge. While national and local air pollution mitigation plans are in place, progress remains slow, coordination is weak, and sources of funding are limited.

Annual and seasonal spatial models for nitrogen oxides in Tehran, Iran

  • Authors:Heresh Amini, Seyed Mahmood Taghavi Shahri, Sarah B. Henderson, Vahid Hosseini, Hossein Hassankhany, Maryam Naderi, Solmaz Ahadi, Christian Schindler, Nino Künzli1, & MasudYunesian
  • Scientific Reports
  • pdf icon مشاهده مقاله

Abstract: Very few land use regression (LUR) models have been developed for megacities in low- and middle-income countries, but such models are needed to facilitate epidemiologic research on air pollution. We developed annual and seasonal LUR models for ambient oxides of nitrogen (NO, NO2, and NOX) in the Middle Eastern city of Tehran, Iran, using 2010 data from 23 fixed monitoring stations. A novel systematic algorithm was developed for spatial modeling. The R2 values for the LUR models ranged from 0.69 to 0.78 for NO, 0.64 to 0.75 for NO2, and 0.61 to 0.79 for NOx. The most predictive variables were: distance to the traffic access control zone; distance to primary schools; green space; official areas; bridges; and slope. The annual average concentrations of all pollutants were high, approaching those reported for megacities in Asia. At 1000 randomly-selected locations the correlations between cooler and warmer season estimates were 0.64 for NO, 0.58 for NOX, and 0.30 for NO2. Seasonal differences in spatial patterns of pollution are likely driven by differences in source contributions and meteorology. These models provide a basis for understanding long-term exposures and chronic health effects of air pollution in Tehran, where such research has been limited.

A GIS based emission inventory development for Tehran

  • Authors:Hossein Shahbazi, Sina Taghvaee, Vahid Hosseini, Hossein Afshin
  • Urban Climate 17 (2016) 216–229
  • pdf icon مشاهده مقاله

Abstract: Tehran with a population of 8.2 million urban residents, suffers from rapid urbanization in recent years resulting in severe air pollution. The aim of this study is to develop a high resolution emission inventory of primary air pollutants for Tehran. Tehran pollution sources are classified into two major categories. Mobile sources, including vehicles such as passenger car, taxi, motorcycle, pickup, minibus, bus and truck, and stationary sources; consisting of industries, general service and household, energy conversion, terminals and gas stations. The emission of SOx, NOx, CO, VOCs and PM in the year of 2013 were estimated as 37.411 kt, 85.524 kt, 506.690 kt, 83.640 kt and 8.496 kt, respectively. The results also indicate that mobile sources produced nearly 85% of the total aggregated pollutants while the stationary sources pollutants accounted for the remaining 15%. In a more elaborated view, 6.22% of SOx, 46.1% of NOx, 97.5% of CO, 86% of VOCs and 69.8% of PM were emitted from mobile sources while stationary sources produced the remaining amount of pollutants

An assessment of gasoline motorcycle emissions performance and understanding their contribution to Tehran air pollution

  • Authors:A. Hassani, V. Hosseini
  • Transportation Research Part D: Transport and Environment, Volume 47, August 2016, Pages 1–12
  • pdf icon مشاهده مقاله

Abstract: Motorcycles are the third most common means of transportation in the megacity of Tehran. Hence, measurements of emission factors are essential for Tehran motorcycle fleets. In this study, 60 carburetor motorcycles of various mileages and engine displacement volumes were tested in a chassis dynamometer laboratory according to cold start Euro-3 emissions certification test procedures. For almost all of the tested samples, the average carbon monoxide (CO) emission factors were about seven times higher than the limits for Euro-3 certification. No motorcycle fell within the Euro-3 certification limit on CO emissions. 125 cc engine displacement volume motorcycles, which are dominant in Tehran, have the most total unburned hydrocarbons and CO emission rates, and they have less nitrous oxides (NOX) emission rates and fuel consumption compared to those of larger engine volume motorcycles. Calculation of fuel-based emission factors and moles of combustion products shows that about 40% of fuel consumed by 125 cc engine volume motorcycles burns to incomplete combustion products. This proportion is lower for larger engine volume motorcycles. Approximation of relative air–fuel ratio results shows very rich combustion in selected motorcycles. Using a carburetor fuel supply system, low engine compression ratio, aging, and no catalyst could be reasons for high emission rates. These reasons could possibly result in high ultrafine particles emission rates from motorcycles. Comparison of total motorcycle pollutant emissions to that of passenger cars from previous studies in Tehran shows that motorcycles contribute to pollutant much higher than their contribution to the total fleet or total travels.

The Relative Contributions of Mobile Sources to Air Pollutant Emissions in Tehran, Iran: an Emission Inventory Approach

  • Authors:Hossein Shahbazi, Masoud Reyhanian, Vahid Hosseini, Hossein Afshin
  • Emission Control Science and Technology, January 2016, Volume 2, Issue 1, pp 44–56
  • pdf icon مشاهده مقاله

Abstract: Tehran, a city with 8.5 million inhabitants, has suffered from rapid and unplanned urbanization in recent years resulting in substantial environmental impacts perhaps fore-most of which is poor air quality. A major source of air pol-lution is emissions from mobile vehicles; therefore, having an accurate and comprehensive mobile source emission invento-ry is essential for decision-makers to develop mitigating strategies. The aim of this study is to determine the relative con-tributions of specific mobile sources to key air pollutants through the development of an emissions inventory for mobile sources in the city of Tehran using the International Vehicle Emissions (IVE) model. Tehran traffic data were acquired to obtain link level emission rates, using IVE emission rates. The developed emission inventory was evaluated using Tehran gasoline sales data. The results indicate that the sources of carbon monoxide (CO), volatile organic compound (VOC), nitrogen oxide (NOx), and sulfur oxide (SOx) emissions are mainly passenger cars. The contribution of emissions of CO, VOCs, and particulate matter (PM) from motorcycles to the total traffic emissions is more than 15, 31, and 12 %, respectively. Despite the fact that medium and heavy-duty vehicles (minibuses, buses, and trucks) only comprise 2.4 % of the Tehran fleet, they contribute more than 41, 64, and 85 % of the NOx, SOx, and PM emissions, respectively. Analyzing the distribution of the aggregated emission of pollutants shows that emissions are mostly higher in central zones due to the high traffic rate of passenger cars, taxis, motorcycles, and buses.

Development of Hot Exhaust Emission Factors for Iranian-Made Euro‐2 Certified Light-Duty Vehicles

  • Authors:Ehsan Banitalebi, Vahid Hosseini
  • Environ Sci Technol. 2016 Jan 5;50(1):279-84. doi: 10.1021/acs.est.5b05611. Epub 2015 Dec 16
  • pdf icon مشاهده مقاله

Abstract: Emission factors (EFs) are fundamental, necessary data for air pollution research and scenario implementation. With the vision of generating national EFs of the Iranian transportation system, a portable emission measurement system (PEMS) was used to develop the basic EFs for a statistically significant sample of Iranian gasoline-fueled privately owned light duty vehicles (LDVs) operated in Tehran. A smaller sample size of the same fleet was examined by chassis dynamometer (CD) bag emission measurement tests to quantify the systematic differences between the PEMS and CD methods. The selected fleet was tested over four different routes of uphill highways, flat highways, uphill urban streets, and flat urban streets. Real driving emissions (RDEs) and fuel consumption (FC) rates were calculated by weighted averaging of the results from each route. The activity of the fleet over each route type was assumed as a weighting factor. The activity data were obtained from a Tehran traffic model. The RDEs of the selected fleet were considerably higher than the certified emission levels of all vehicles. Differences between Tehran real driving cycles and the New European Driving Cycle (NEDC) was attributed to the lower loading of NEDC. A table of EFs based on RDEs was developed for the sample fleet.