ABSTRACT
Objectives：The aims of this study were to investigate the background concentrations of airborne inorganic acid and basic species in the vicinity of Central Taiwan Science Park（CTSP）and to clarify how the emissions from the industries of the park and meteorological condition affect the concentrations.
Method：Factories in the CTSP started to operate in June 2005. This study was conducted using ISC3 model. Ten sampling stations were established for collecting air samples for laboratory analysis and monitoring meteorological data from March 2005 to February 2006. Samples were subject to quantitative analysed using the ion chromatograpy. The emission of sulfuric acid and hydrochloric acid in the park was not permitted until February 2006. The emission of other inorganic acid such as nitric acid and hydrofluoric acid, and ammonia in the park started June 2005.
Results：
1. The average background concentration of sulfuric acid gas for the year was 10.95μg/m3, with 5.50 μg/m3 as sulfate (SO42-) (No emission in the park). The corresponding concentrations were 10.95 ppb of HCl gas and 1.12 ppb of the chlorate (Cl-) in the same year.
2. The average concentrations for other ingorganic acids measured in the first three months in this study were 0.78 ppb HNO3/HNO2 , 4.11 ppb nitrate (NO3-),15.30ppb NH3 gas,3.46ppb ammonium (NH4+), 0.64μg/m3 HF gas, 0.52μg/m3 fluoride (F-) and 1.16μg/m3 total fluoride.
3. There were no significant differences for most pollutants between the background values and concentrations measured in the emission permitted period, except hydrofluoric acid. The hydrofluoric acid concentraction was doubled during the emission period（from 0.64μg/m3 to 1.21μg/m3）. However, the average concentrations of all species did not exceed the permitted discharge levels.
4. The distributions of all species skewed to the right. The distributions of nitric acid gas, sulfate, chlorate, amonia and ammonium concentrations were logistic normal.
5. We also found that the increased humidy was associated with increased concentrations of hydrochloric acid gas, hydrofluoric acid gas, fluorate and the total fluoride. Higher temperature was associated with reduced chlorate concentration and increased sulfate concentration. The concentrations of all species increased as the wind speed decreased.
Conclusions：Hydrofluoric acid is the only substance measured in the samples with the concentration significantly higher than the background value. There are no significant differences between the background levels and the measured levels of all other pollutants while the industries in the park were in operation.
