GAW Report No. 205 - IGAC Project

CHAPTER 3 - ASIAFigure 32 - Annual mean concentrations of PM10 inMetro Manila for the period 2001-2008.Red line: NAAQGV value of 60 µg m -3 ;Green line: WHO AQG of 20µg m -3 [CAI-Asia, 2009]Figure 33 - Annual mean concentrations of PM2.5for the period 2001-2008.Red line indicates WHO AQG of 10 µg m -3[CAI-Asia, 2009]The Manila Observatory (MO) participated in the Asian Regional Air Pollution ResearchNetwork (ARPET), coordinated by the Asian Institute of Technology [Oanh et al., 2006]. DuringPhase 1 of ARPET (2001-2004), MO collected over a thousand PM 2.5 and PM 10 samples at fivesites in Metro Manila using both MiniVol and dichotomous samplers. Table 9 presents the results ofARPET Phase 1 for Metro Manila for both the dry and wet seasons.Table 9 - ARPET Phase 1 Results for Metro Manila averaged over all samples. [Oanh et al., 2006]RangePMSizeSeason Number of Samples Mass in µg m -3PM2.5 Dry 407 44PM10 Dry 122 54PM2.5 Wet 376 43PM10 Wet 136 55From the data in Table 9, it is clear that seasonal average PM 2.5 concentrations in MetroManila already exceed the current WHO 24-hour AQG of 25 µg m -3 in both dry and wet seasons,while seasonal average PM 10 concentrations are almost within the WHO 24-hour AQG of 50 µgm -3 in both dry and wet seasons.Limited monitoring of other criteria pollutants (SO 2 , NO 2 , and O 3 ) has been conducted inMetro Manila. The concentrations of SO 2 and NO 2 are below the NAAQGV at the monitoringstations, while O 3 concentrations exceed the one-hour guideline on most days at one stationbetween 2001-2002 [World Bank, 2002], but are relatively low elsewhere.Sources of air pollutants and emission inventoriesThe DENR conducted a national emissions inventory of air pollution sources in 1990 andsubsequently updated the inventory in 2001, 2004, and 2006 as mandated by the Philippine CleanAir Act. The emissions inventory includes criteria pollutants such as PM, SO 2 , NO X , CO, and VOCs.According to the latest (2006) inventory, the transportation sector is the major source of air pollutioncontributing about 65% of the pollutants, while 21% is from stationary [point] sources and 14% fromarea sources, with total national emissions of seven million tons per year from all sources [DENR,2009]. The same emissions inventory shows that CO has the biggest pollution load contribution of50%, followed by NO X at 15%, VOCs at 15%, PM at 11%, and SO X at 9%. CO emissions arecaused by the increasing population of gasoline-powered vehicles, which include cars (13.6%) andmotorcycles/tricycles (47.9%) [DENR, 2009].101