تحلیل وضعیت بلندمدت آلاینده‌های اصلی و تعیین دوره‌های آلودگی هوا در کلان‌شهر تهران

آلودگی هوا و تغییرات اقلیم دو معضل کنونی جوامع انسانی هستند که از طریق فرآیندهای تابشی، دینامیکی و شیمیایی باهم مرتبط بوده و برهم تاثیر متقابل دارند. افزایش آلاینده‌های اصلی هوا طی واکنش‌های شیمیایی و فتوشیمیایی در جو با برهم‌زدن تعادل انرژی کره‌زمین سبب واداشت تابشی شده و دستاوردهای سریع منفی آب‌وهوایی همچون گرمایش جوی را به‌همراه دارند. با توجه به اهمیت این مساله و باهدف دست‌یابی به‌یک رویکرد یکپارچه و مشترک در کاهش آلودگی هوا و تعدیل تغییرات آب‌وهوایی، آگاهی از وضعیت آلاینده‌های اصلی از دیدگاه تغییرات اقلیمی امری ضروری است. در این پژوهش جهت مطالعه وضعیت سالانه، فصلی و ماهانه بلندمدت (1396-1381) شاخص (aqi) و غلظت شش آلاینده‌ ( ) از داده‌های شرکت کنترل کیفیت هوای تهران و برای تحلیل آماری از روش آماری برآورد (تخمین) روند خطی سری زمانی، توزیع فراوانی و محاسبه درصد تغییرات استفاده‌شده‌ است. نتایج نشان می‌دهد که سطح غلظت اکثر آلاینده‌ها (به‌استثناء co  بهبودیافته) بیش از دو تا 4 برابر حدود استانداردهای ملی و بین‌المللی است. متوسط شاخص (aqi) سالانه نیز در سال‌های اخیر (1396-1389) با آلاینده معیار ( ) رشد نامطلوب 11% داشته که این افزایش در زمستان به‌عنوان نامطلوب‌ترین پیک آلودگی فصلی با رشد 24% در شاخص کیفی و 70% در فراوانی روزهای آلوده همراه بوده و بیشینه ماهانه آن نیز در آذر و دی است. لذا تدوین استراتژی‌های میان‌مدت سخت‌گیرانه‌تر در کاهش گسیل آلاینده‌های جوی نه‌تنها در بهبود آلودگی کلان‌شهر تهران موثر است بلکه می‌تواند همسو با تلاش‌های بین‌المللی سیاست‌های بلندمدت در تعدیل تغییرات اقلیمی را پشتیبانی کند.

Long Term Status Analysis of Major Air Pollutants and Determination of Air Pollution Periods in Tehran Metropolis

Air pollution and climate change are two of the most serious problems facing human societies which interact with each other through radiation, dynamic and chemical processes. Increasing air pollutants some as greenhouse gases in addition to adverse effects on health, economic and social sectors of societies, during chemical and photochemical reactions in the atmosphere, disrupt the Earth’s energy balance and cause radiation forcing and rapid negative climate gains, such as global warming. With the recent climate change the quality of life of urban communities is also facing a serious threat. With the importance of this issue and with the aim of achieving a unified approach to reducing air pollution and mitigating climate change, it is essential to know the quality of major air pollutants in the face of recent climate change. In this study, longterm data (20022017) of Tehran Air Quality Control Company were used for analysis of annual, seasonal and monthly air quality conditions and changes of trends of air pollutants concentrations and the air quality index (AQI) of six major air pollutants ( ). Also, for the statistical analysis, linear regression model, frequency distribution and calculation of variation percentage were used. According to the results, the air quality of Tehran is in a poor condition due to concentrations of more than two to four times the national and international standards of most pollutants (except CO and SO2 which have improved). So that during 16 years of study according to the highest values of AQI and the highest frequency of contaminated days, three general air pollution periods (20022006:CO), (20072009: ), (20102017: ) were determined for Tehran. Accordingly, the third period with an (11%) unfavorable growth in average annual AQI and a decrease (19%) in total frequency of desirable days (184% clean, 13 healthy) and increase (33%) in total adverse days, especially unhealthy days for sensitive groups (35%) was the most affected period compared to that of the other previous two periods. In the third period of air pollution only about (2%) of the days of the year were at the clean level and more than one third of the days (36%) with the criteria air pollutant ( ) contaminated. Also, seasonally due to the influence of the specific weather conditions of each season on the exacerbation of adverse pollutants status, two peak of pollution in cold and hot periods of the year were determined. In hot seasons,)41%( of the annual contaminated days were recorded, especially in summer (%23) due to high concentrations of pollutants (  (70%),  (27%) and  (3%)). The monthly pollution peaks of this period are also in June, July and August respectively. The peak of pollution in cold period of the year was designated as the most polluted peak. During this period, 59% of the frequency of adverse annual days, especially in winter (31%), was recorded due to high concentrations of pollutants (  (87%),  (10%)and  (3%)) have been in December, January and February respectively. Also, in recent years (20102017), the winter pollution peak has been associated with a )24%( increase in the quality index and 70% in the frequency of contaminated days. Therefore, due to the direct and indirect effects of air quality pollutants in the face of aggravating climate change, in addition to the need to further reduce longterm greenhouse gas emissions in related policies, formulating stricter strategies to reduce pollutants emission in urban areas as Tehran should be improvised.