Comparison of Several Methods for Nitrogen Dioxide and Sulfur Dioxide in Metro Manila Air

The pollutant gases nitrogen dioxide (NO2) and sulfur dioxide (SO2) are two of the commonly monitored parameters for air quality assessment in the Philippines. In this study, several active and passive sampling methods for the analysis of the two gases were tested. Of the methods for NO2 first tested indoors, the NaI sorbent passive sampling method was found most promising and was tested for ambient air NO2 (using both Ferm and Korean passive samplers) against a collocated automated chemiluminiscence sampler. For SO2, ambient levels were simultaneously measured using NaOH sorbent in a Ferm passive sampler and a collocated automated fluorescence sampler. Correlation and t testing indicate a positive bias for the NO2 Ferm method and a negative one for the SO2 Ferm method in comparison with their corresponding automated methods. The results of the study support the 1997 annual average SO2 and NO2 findings of a UP Natural Sciences Research Institute (NSRI) study (Quirit et al, 1999) which used Ferm passive samplers in various Department of Environment and Natural Resources (DENR) Metro Manila air sampling stations.