Critical Transformational Time of Ground Level Ozone from Nitrogen Dioxide in Urban Area

Abstract

The prior aim of the study is to investigate the characteristic of the ground level ozone from its main precursor during critical transformation time in urban area. The analysis was carried out using the dataset of three selected urban area from 2013 to 2014. The mean O3 concentration recorded throughout 2013 and 2014 in Kota Bharu, Putrajaya and Shah Alam is 15.56 ppb, 21.34 ppb and 19.17 ppb, respectively, while the mean O3 concentration during critical transformation time (CCT) is 13.07 ppb, 13.51 ppb and 12.14 ppb, respectively. It has been found that the O3 concentration is high starting from March to May due to the Southwest monsoon season in Putrajaya and Shah Alam. However, O3 concentration in Kota Bharu is recorded to be the highest starting approximately from May 2013, while in 2014, the O3 concentration is high starting from January to February, then from April to August. The CCP was observed to be occur within the CCT, between 8.00 a.m. and 11.00 a.m., using the diurnal plot and the O3 maxima was observed, usually after CCT at approximately 2.00 p.m. to 4.00 p.m. The finding clearly showed that the CCT period is an important period in O3 daily fluctuation that should be given more attention to understand this air pollutant.