Comparative study of the environmental challenges in core areas, Medial and periphery cities) Case study: two regions, eleven and twenty-two in Tehran (

Introduction
The current environmental challenges one of the main concern of is humanity. The issue of when more Added concern has been associated with complications. Research suggests the environmental challenges are rooted in factors in the different levels of global, regional and local levels are considered. In this case although many studies have been In Different aspects of urban environment is done, But a new look Spatial and geographical view could be new dimension of factors and environmental impact it makes evident.
Extent of existing pollution, in the urban areas of boundaries traditional pollution exceeded. Today in the environmental science of Pollution study of the Due to advances in industry and technology as has become the most important issues of the day. It seems, the different urban spheres (center, intermediate tissue or periphery areas) In Tehran with Different degrees Of Invasion of the Adverse environmental effects and risks have been, so that residents And the physical body Exposed to damage and injuries Are placed unwanted. Tehran city One of the most polluted cities in the world. In the current situation of Country Which Tehran as Mastermind behind and management Country is considered and pollution Tehran Has become a regional and national issue. It cleans the air not only the health of In Tehran but also increases the country health.
The aim of the present paper compares the environmental challenges in tissues of central, intermediate and peripheral in the metropolis of Tehran.
Materials and methods
Research Methodology In this study, a descriptive study - analytical and research type applications and approach of, it is both quantitatively and qualitatively. Data collection Research needed of through studies of library and use of documents the data collected by field by the relevant organizations and also the use of Projects was carried out the relevant in the three regions (2-11-22) in Tehran.
Assess environmental challenges Mentioned areas in three phases hierarchically and systematically is done, is provided below. It is notable that the three stages of the form expanded in the section analysis have been expressed.
Stage First: determine the parameters Types of pollution (air, water, soil and noise) and weighting their importance
Stage Second: normalizing and determine the severity of the amount of pollutant parameters in the three regions
Step Three: Determine the relative intensities the amount of pollutant parameters and calculate the final score in three regions
Results and discussion
For a better understanding of the environmental challenges in the three regions (2-11-22) Tehran, Type of pollutants  Mentioned areas individually, based on the source and origin of pollution (natural – human), Causes of aggravating of the pollution the effects of pollution on various factors like humans, plants, animals, and the urban fabric (buildings) are described.
Based on the results of the calculations, the final score Air Pollution in the zone 11, weighing 409.34 Than Zone 2 and 22 Has the greatest pollution. Regions 2 and 22 Respectively 316.76 and 273.90 with weights have acquired. Region 2 Also air pollution is high. But Region 22 Better conditions than other two regions. But the main factor of Higher air pollution in the Region 11 Caused by There are extensive sources of carbon monoxide, sulfur dioxide and industrial workshops, The high production rate and attraction trip And so is above area.
In terms of pollution of water and soil, Region 11 with a score of 553.8 most contaminated Shows, Region 2 with a score of 304.0 in the second row And Region 22 with a weight of 142.2 the lowest of pollution is placed in the third level.
In terms of noise pollution, at Region 11 with a score of 492.88 from most Noise pollution indicate, Region 2 and 22 respectively with scores of 305.06 and 202.06 in the next rows are placed. The main causes of Cars More traffic because the focus of medical centers, educational, administrative and commercial 11 regions is. )Figure 1(
 
 
Figure 1: Average weight challenges of biological (air, water, soil and noise) of the triple (2-11-22) in Tehran
 
 
 
 
 
 
 
Map 1: Status of challenges of biological in the triple (2-11-22) Tehran
 
Conclusion
The growth urbanization and Excessive use of fossil fuels In Cars Industries in the city Become to intensify Environmental crises in urban areas .Currently, Environmental challenges one of the most fundamental Concerns of urban human society especially for urban specialists is considered. Thus, studying the environmental challenges of urban community one of the necessities Understanding urban issues the current situation is. With a vision and a deep understanding from situation in urban environment more fundamental steps to fix environmental challenges to achieve a City High Environmental Quality to be removed.
The results of this research show the region 11 with the acquisition the highest final score The 502.455 Environmental pollutions most is. Region 2, with a final score of 307.455 with the a small distance in the second row And District 22 with the final score of 190.09 in the third row takes place The District 22 Relatively favorable conditions Of environmental is.
Most causes of Contaminants Region 11 in Tehran than Regions 2 and 22, Due to exposure In a specific geographical location And establishment of the central part of the urban and Followed the presence of high levels of pollutants Such as Produced and attracted high of travel, Most industrial workshops, Production of aerosols, Production of carbon monoxide and other polluting sources of direct and indirect The essential role of in the environment it is undesirable to play. Actually Region 11 than the 2 and 22 per unit area most pollution of air, water, soil and noise In Tehran is produce.