Hydrogen peroxide concentrations in the ambient air of Seoul, Korea

Gas-phase hydrogen peroxide (H2O2) was measured to investigate its distribution in the ambient air of downtown Seoul. These measurements were made during all four seasons, from 12 February, 1998 to 16 September, 1999, using the cold trap method and HPLC with fluorescence detector. Simultaneous measurements were also made of other photochemical oxidants and trace gases (O3, NO2, CO and SO2) and meteorological parameters (relative humidity, temperature, solar radiation and wind speed). The mean of all observations for hydrogen peroxide was 0.081 ppbv and the measured range was below the level of detection (<0.01 ppbv) to 0.380 ppbv. The highest mean (± standard deviation) concentrations appeared during the summer (0.104±0.068 ppbv, detection limit 0.380 ppbv) and the lowest concentrations were seen during the winter (0.042±0.021 ppbv, detection limit 0.098 ppbv). Gas-phase hydrogen peroxide showed a diurnal variation with maximum concentrations in the afternoon. From correlation analysis results, the relationship between gaseous H2O2 and some parameters [O3 (r=0.37), temperature (r=0.42), aldehydes (r=0.41)] showed positive correlations. Negative correlations between H2O2 and others [NO2 (r=−0.34), CO (r=−0.41), and SO2 (r=−0.30)] were seen. Thus, as expected, photochemical activity, competing reactions and primary pollutant concentrations appeared to be the most significant factors in controlling the gas-phase H2O2 concentration in Seoul during the measurement period.