GAW Report No. 205 - IGAC Project

CHAPTER 3 - ASIAThe scale of this air quality problem is huge, with the economic impact of air quality onIranian economy and population health estimated at US $7 billion; equivalent to 8.4% of GrossDomestic Productivity [GDP; Shafie-Pour and Ardestani, 2007]. Though there are numerouspublications on this issue in Farsi, only a few internationally published scholarly papers focus on airpollution and its environmental impacts in Tehran.Emission sources of air pollutantsEmissions in Tehran are from mobile sources (transport), stationary sources such asindustries (mostly in the outskirts), and residences. By far the worst offender, mobile sources areestimated to contribute a massive 89% of the total emission by some studies; other studies suggestthat this contribution might be smaller, at approximately 71%. As this would indicate, Carbonmonoxide (CO) and PM 10 are the main concern for air quality in Tehran.Emission(ton/annum)Table 16 - (Data from Air Quality Control Company, AQCC)Mobile Sources PercentagecontributionStationary SourcesCO 1,354,652 99 18,222 1SO2 6,142 10 57,173 90NOX 109,917 70 46,253 30THC 155,609 71 64,761 29PM 18,777 69 8,444 31PercentagecontributionTable 16 summarizes the relative and absolute contribution for each emission source in2005. Mobile emission inventory surveys for Tehran cover emissions from light duty vehicles,private cars, motorcycles, public transport buses, and trucks. According to an Air Quality ControlCompany (AQCC) study performed in 2005, the contribution of light duty vehicles to air pollutioncaused from mobile sources has been estimated to be close to 50%. Factors that determine such ahigh contribution by the transport sector are complex, including government subsidized inexpensivefuel, which can be of poor quality (unleaded gasoline became available after 2001), and largenumbers of older, domestically produced cars.Data available on air pollutantsThere are approximately 13 permanent ambient air monitoring stations dispersed throughoutTehran, which are operated by AQCC and the Tehran Municipality. Daily and hourly averaged dataare available for CO, NO X , SO 2 , HC, TSP, O 3 and lead.The status and trend of the pollutionAs mentioned above, international scholarly work on analysis of in situ data is rare forTehran. Yet some good examples can be found; Halek et al. [2004] examined the monthly averagesof PM 10 for 2003 and discovered that autumn tends to have the highest concentrations and springthe lowest. Maximum values were observed in September at just over 370 µg m -3 ; the minimum wasreached in April at 65 µg m -3 . Hassanzadeh et al. [2009] show that SO 2 has a seasonal patternsimilar to that of PM 10 . Monitoring SO 2 levels at 5 monitoring stations for the period of 2000-2005,they concluded that at most sites SO 2 concentration fluctuations were similar.A link between hospital admissions due to angina pectoris and several pollutants wasestablished by Hosseinpoor et al. [2004]. This study established that exposure to CO provided theclearest link to negative health outcomes for the population in Tehran, although the confoundingrole of other pollutants was acknowledged.Shirazi and Harding (2001) provide information on trends for some common pollutants suchas CO and particulate matter (PM) for the period between 1988 and 1993. Indicating a rapid upwardtrend for most pollutants except NO 2 , they point out that all pollutants except TSM routinely andsubstantially exceeded WHO guidelines. These findings suggest that as the population continues togrow, and drives increasing numbers of motor vehicles, there will be a corresponding increase in129