Abstract
One of the main challenges for countries in tropical areas is the high concentration of ozone caused by elevated levels of anthropogenic and natural ozone precursors. In this study, variations in O3 concentrations from urban, suburban and rural regions of the Malaysian Peninsula were investigated using data covering a five-year period (2005–2009) obtained from the Malaysian Department of the Environment. The principal aim of the study is to identify and describe the variations in O3 concentrations recorded at three monitoring stations with different backgrounds, namely Petaling Jaya (S2) (urban), Putrajaya (S1) (suburban) and Jerantut (S3) (rural). The study also investigated the relationship between O3 distribution and its association with nitrogen oxides (NO and NO2) and non-methane hydrocarbon (NMHC). The results showed that the highest O3 concentration was recorded in a suburban area (Putrajaya (S1) with an average daily maximum value of 60 ± 20 ppbv). The O3 concentration was influenced by the characteristics of nitrogen oxides, particularly the titration of NO. The surface O3 level was found to be influenced by solar radiation and wind direction from the busy areas, most notably Kuala Lumpur's city centre. This study suggests that the emission of O3 precursors, particularly NOx from motor vehicles, needs to be regulated to reduce the incidence of high O3 levels in Malaysia.
Highlights
Ozone (O3) is considered to be secondary pollutant, photochemical oxidant and the main component of smog
The results showed that of the three stations, suburban Putrajaya (S1) had the highest hourly O3 concentration with 148 ppbv as recorded in 2006, followed by the urban area of Petaling Jaya (S2) which had an hourly maximum of O3 of 140 ppbv in 2005
The fact that the concentration of O3 recorded was higher in the suburban area of Putrajaya (S1) than that for urban Petaling Jaya (S2) is confirmed by the overall daily average and average daily maximum concentrations recorded at these two stations (Table 3)
Summary
Ozone (O3) is considered to be secondary pollutant, photochemical oxidant and the main component of smog It is regarded as a crucial air pollutant in the atmosphere because O3 is capable of causing damage to human health via respiratory disease (Ho et al, 2007; Karakatsani et al, 2010; Neidell and Kinney, 2010; Mills et al, 2011; Huang et al, 2012). The backward trajectories for the two main stations, namely Petaling Jaya (S2) and Putrajaya (S1), were developed for 72 h for the O3 episode event when the O3 concentration exceeded the limit of 100 ppbv for 1 h averaging time (the maximum value recommended by the Malaysian Air Quality Interim Guidelines, RMAQG). Three dates for highest O3 episodes were chosen for backward trajectory for the Petaling Jaya and Putrajaya stations when the concentration of O3 recorded was at the highest level. The selected dates for Petaling Jaya station were as follows: 7th June 2009 (southwest monsoon), 12th June 2009 (inter-monsoon) and 30th December 2009 (northeast monsoon), while those of Putrajaya were 5th February 2009 (northeast monsoon), 1st April 2009 (northeast monsoon), 13th April 2009 (northeast monsoon)
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