Assessing the effectiveness of air pollution control programs in Tehran using air quality trend analysis

Population growth, traffic jam, and industrial development generate air pollution in metropolises such as Tehran. Regarding the fact that air pollution can cause serious damage to the health of citizens, various studies have been conducted at the national and international levels. Undoubtedly, one of the most important ways to reduce environmental pollution is the use of control programs and measures. Therefore, this study aims to evaluate the effectiveness of some plans and programs to reduce the air pollution of Tehran capital city.

To determine the annual fluctuations in air pollutants (Carbon Monoxide (CO), Particulate Matter of 10 microns in diameter or smaller (PM10), Ozone (O3), Sulfur Dioxides (SO2), Nitrogen Dioxide (NO2), and Nitrogen Monoxide (NO), the concentration of these parameters was investigated in Tehran from 2005 to 2012. Pearson correlation analysis and stepwise regression (SAS software) were used to evaluate the relationships between air pollution, number of vehicles and fuel consumption in Tehran.

From 2005 to 2012, the trend of annual changes in CO concentration was decreased. The highest concentration of this pollutant (2006) was 5 mg/l and the lowest concentration (2011) was about 2 mg/l. During the same period, the annual trend of PM10 increased from 100 to140 μg/m3. In these years, the annual trend of ozone decreased from 0.03 mg/l to 0.02 mg/l. Meanwhile, the annual concentration of sulfur dioxide decreased from 0.055 to 0.03 mg/l. Changes in annual NO2 and NO concentration decreased during the mentioned years from l0.07 to 0.2 mg/l and from 0.05 to 0.010 mg/l, respectively.

Results show that the trend of annual change in the concentration of pollutants was decreasing for all pollutants (except for suspended particles) from 2005 to 2012. Eliminating eroded cars, and using hybrid and gas-fueled vehicles played an important role in reducing air pollution in Tehran. Also, due to the results of the correlation analysis and the significance of the effect of eroded cars on atmospheric pollutants, the impact of this policy on reducing emissions was significant. The results of stepwise regression analysis from 2005 to 2012 showed that eliminating the eroded cars and replacing them with dual-fuel ones had the most significant effect on reducing carbon monoxide emissions in Tehran.