Long-term and consistent spatial-temporal quantification of fine particulate matter is needed in Metro Manila as past studies focused only on total suspended particulate matter. Quality assured and controlled fine particulate monitoring was done from 2000-2008 by Manila Observatory at 5 sites in Metro Manila, one site in Cebu City and a remote site. Monitoring results revealed that among the sampling sites in Metro Manila, average PM2.5 concentration was highest in NPO (traffic site), followed by Pasig (industrial site) and PGH (commercial site) with averages of 72 μg/m3, 49 μg/m3 and 45 μg/m3, respectively. In Cebu city, average PM2.5 concentration was 30μg/m3. The lowest level was observed at the remote site of Gabaldon with PM2.5 below 22 μg/m3 and PM10 below 30 μg/m3 in both seasons.
Most of the PM10 in Metro Manila was made of the fine fraction or PM2.5, with increasing levels when getting close to the major roads. Transport, hence, appeared to be a major contributor to elevated fine PM in Metro Manila. Research activities for the past eight years have produced particulate matter data that enabled composition and source apportionment analysis. Past PM composition analysis has shown that black carbon or soot is of major importance in the PM2.5 collected in Metro Manila. Analysis for effects of rain on PM samples in Manila Observatory showed that the coarse fraction of PM seems to be washed out more effectively by rain. Source apportionment using receptor models revealed traffic as the main contributor to PM2.5 at all sites in Metro Manila while biomass burning appeared to be the highest contributor to the fine fraction in the areas outside Metro Manila. More work in analysis of major emission sources and the interrelationship between meteorology and PM pollution would be required to understand the major factors influencing PM pollution in the study area and to refine air quality management strategies that have been suggested in the past.