ACIDIC AND ALKALINE CONSTITUENTS OF AIR PARTICULATES WITHIN DWELLINGS

The acidic and alkaline substances of indoor and outdoor PM10 aerosol samples were collected simultaneously in 15 domestic environments in t he Taipei urban area; 10% of indoor and 20% of outdoor PM10 levels exc eeded the USEPA 24 h standard for PM10 (150 mug m-3). The mean indoor concentrations of Na+, K+, NH4+, Cl-, SO4(2-) and NO3- were observed t o be 52, 16, 206, 20, 114 and 50 nmol m-3, respectively. The mean outd oor concentrations of the ions mentioned above were 56, 18, 234, 32, 1 30 and 65 mmol m-3, respectively. Moreover, the mean concentrations of the indoor and outdoor excess SO4(2-) were observed to be 112 and 127 nmol m-3, respectively. On average, the sum of the six analyzed ions constituted 20% of the total mass concentration from the indoor and ou tdoor PM10 samples. The major portion of the acid present in Taipei ae rosols is associated more with SO4(2-) than with NO3-. Furthermore, si gnificant correlations of SO4(2-) with NH4+ and NO3- were observed, an d aerosol sulfates are neutralized by atmospheric ammonia to form (NH4 )2SO4. In addition, the indoor and outdoor SO4(2-)/Na+ ratios were fou nd to be much higher than that of sea-water, indicating a SO4(2-) orig in from anthropogenic sources.