Study of Persistence of Polluted Days with Carbon Monoxide (CO) in Tehran City Using Markov Chain Model

Introduction & Air pollution is one indication of the urbanization, population incensement, excessive use of fossil fuel resources, lack of utilizing environmentally friendly technologies and most importantly lack of proper environmental management are some the factors which play big roles in this matter. Establishment more than ten million people and excessive concentration of industries and factories, alongside with the geographical situation, topography and specific climatic region, have made Tehran one of the seven polluted cities in the world. In the assessment of air quality, concentration of carbon monoxide gas (CO), among the various pollutants, has a main role and importance. In this study, the probability of persistence of two to seven days unauthorized amounts of pollutants CO in city of Tehran was investigated. For this purpose, the 5-year data (2002- 2006) related to five stations measuring air quality of pollution control companies of Tehran were collected and then using first-order, two-state Markov chain were modeled. Results showed that the highest probability of persistence of pollutant CO exist in Fatemi station, Bazar and Aqdasiyeh stations are sat at next orders. Many months of the year, Fatemi station has the highest probability of CO and two stations, Bazar and Aqdasiyeh, are located in next ranks. Meanwhile, the persistence of pollutant CO in Shahr-e-Rey station compared to other stations is the least.