Ground level ozone (O3) is a noxious air pollutant that Imposed adverse effect to human
health, crop yield and the environment. Hence, it is important to understand their fluctuation
and transformation characteristic which is still regarded at its infancy stage in Malaysia to
properly design abatement and control strategies. Therefore, this study aimed to Investigate
the characteristics of O3 fluctuation and transformation from its precursors as well as to
introduce the critical conversion point (COP) of O3 formation. Next hour O3 prediction
models during daily, daytime, nighttime and critical conversion time were also developed
using multiple linear regression and principal component regression to predict O3
concentrations in different group of monitoring stations. This study consists of 18 areas across Malaysia from 1999 to 2010. Although an ovenwhelming majority of the recorded
data are below the prescribed levels in the Malaysian Ambient Air Quality Guidelines, total
of 1,988 hour of exceedences have been recorded with majority contributed by Shah Alam.
O3 diurnal cycles suggest a unimodal peak between 12 pm to 4 pm, while minimum
concentration is consistently measured on 8 am. Results of PCA showed the contributions
to O3 variation by NO2, NO, T and UVB is up to 80%, whereas the composite diurnal plots
confirmed that variation is highly depend on NO2 and NO concentrations. The CCP of O3
formation were identified to occur in between 8 am to 11 am. MLR model based on cluster
group during daily exhibited optimal performance in terms of coefficient of determination,
prediction accuracy, and index of agreement with values of 0.9351, 0.9671 and 0.9831,
respectively. Although the optimal model was during daily, the developed models using
critical conversion time were more consistent with minimal differences between MLR and
PGR in terms of error and accuracy. Effective ground level ozone control, need strategic,
systematic and concerted efforts amongenvironmental related agencies in Malaysi
