Assessment of high nighttime ground-level ozone concentration in Kemaman

Ground-level ozone was a pervasive air pollutant due to its harmful effect on living things. In this research, the concentration of nighttime ground-level ozone and its precursors were determined, starting from 7 p.m. to 7 a.m. using descriptive analysis, box and whisker plot and time-series plot in Kemaman, Terengganu. Besides, diurnal plot was also used to illustrate the mechanism of nighttime ground-level ozone removal chemistry. Multiple Linear Regression was used to fit the data obtained from site to predict the response outcome of selected variable to ground-level ozone concentration. This study showed that the concentration of ground-level ozone has a mean of 16.11 ppb in Kemaman. Diurnal plot illustrated that the concentration of ground-level ozone had decreased over time while the concentration of adjusted nitrogen dioxide still remained high. Along the period of monitoring, the highest concentration of ground-level ozone recorded was 51 ppb in Kemaman. The R2 value for primary data was moderate, which was 0.408, indicating the selected variables have explained less possibilities in variation of ground-level ozone concentration. The concentration of ground-level ozone in Kemaman monitored was lower than the nitrogen dioxide because it was raining along the monitoring period and also because of the nighttime ground-level ozone removal chemistry. On the other hand, the R2 value for secondary-data was low, 0.052, which indicates the selected variables have explained less possibilities in variation of ground-level ozone concentration. This was probably due to a lot of missing data.