Background: Air pollution is a major problem in urban\industrial areas, like Tehran, and has several impacts on human health. This study aimed at assessing concentrations of criteria air pollutants (CO, SO2, NO2, O3, PM10) in Tehran, extracting patterns of hourly, daily, weekly, and monthly variations of concentrations, and making comparisons to National Standards and WHO Guidelines.
Methods: Air quality data were taken from Air Quality Control Corporation and 5 sampling stations (out of 13) were selected for analysis according to data availability. Microsoft Excel 2003 was used for data analysis and plotting the charts.
Results: Patterns of temporal variation (hourly, daily, weekly, and monthly) of air pollutant concentrations were extracted. In some cases extracted patterns matched with the patterns proposed by other researchers. Pollutant concentrations were compared to National Standards and WHO Guidelines and it was observed that in most of the days, we exceeded the limit values.
Conclusion: Air pollution in Tehran is quite high and there are many days that we exceed the standards; therefore appropriate control strategies are needed. Although the number of sampling stations is high enough to be representative of whole city, it is proposed that an independent sampling station is setup to check the validity of the measurements.
Keywords: Air quality assessment, Pollutant concentrations, Temporal variations, Air pollution control
In normal situation, the environment has the potential to neutralize impacts of natural and anthropogenic air pollutants. However with increasing pace of urbanization and industrialization, air pollution has overcome the environment and arisen as a major problem in such areas. In spite of covering only 0.04% of country's total surface area, Tehran, the capital of Iran, accounts for 13% (9 millions) of the total country's population; hence, it is known as a highly populated area. In Tehran, like other populated areas in the world, vehicular and industrial emissions are the major sources of air pollution (1-3).
Since people are continuously exposed to air, pollutants in the air can easily enter the body and cause adverse effects on human health both in short- and long-term. Therefore, many investigations have been conducted on the health impacts of air pollution (4-6) and it's been found that such effects mainly include hospital admissions (7,8), respiratory diseases (9,10), cardiovascular diseases and premature deaths (11,12), and neurobehavioral effects (13). Its been proved that a vast majority of people are concerned about such effects and are willing to pay for improving the air quality (14).
Facing such a problem and proposing appropriate strategies for it require integrated air quality assessment, as EU requires its member states to assess the air quality by means of measurement or modeling (15). Hence, developed and some of the developing countries have been conducting extended investigations on the air quality assessment (16-25), emission inventory development (26, 27), assessment of temporal variations of air pollutants concentrations (28, 29), and development of air quality assessment models (30, 31), and some of them have resulted in proposing strategies for air quality improvement (2). International organizations have also published a variety of guidelines and standards as well (32, 33). In Iran, however, less attention has been paid and only a limited number of investigations have been done in this issue (34-37). National Standards (38) are also published regardless of the way we can comply with them. Another problem in air quality assessment is the large number of missing values (15, 39).
Tehran is located in the longitude of eastern 51° 8' to 51° 37' and the latitude of northern 35° 34' to 35° 50', covers a total surface area of 730 km2, and has a population of 9 million. The increasing numbers of motor vehicles as well as large numbers of existing industries are known as the major sources of air pollutants in this area. …