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Volume 15, No. 4, August 2015, Pages 1357-1366 PDF(1.05 MB)  
doi: 10.4209/aaqr.2015.01.0031   

High Nighttime Ground-Level Ozone Concentrations in Kemaman: NO and NO2 Concentrations Attributions

Norrimi Rosaida Awang, Nor Azam Ramli, Ahmad Shukri Yahaya, Maher Elbayoumi

Clean Air Research Group, School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang, Malaysia


  • The occurrences of high nighttime O3 in Malaysia as Tropical country is analysed.
  • HACA, is used to assess the sources of atmospheric pollutants at nine stations.
  • The stations has been categorized into three different clusters base on locations.
  • Lower concentration of NO 1.1 ppb reduced NO titration reactions during nighttime.
  • Nighttime NO2 might contribute to high nighttime O3.



High nighttime ozone (O3) concentration levels were observed in Kemaman, Terengganu, and results were compared with those in other places in Malaysia. In this study, the contribution of precursors [nitric oxide (NO) and nitrogen dioxide (NO2)] and meteorological factors wind speed, and wind direction) toward long-term high nighttime O3 over the period of 1999 to 2010 was evaluated. During this period, the recorded highest nighttime O3 ground level was 89 ppb with more than 25% surpassing 20 ppb. Analysis shows that minimal decreasing trends were measured in Kemaman. Lower nitrogen oxide (NOx) concentrations restricted the sinking agents; thus, reducing the depletion rates allowed O3 to remain in the atmosphere. Minimal associations were observed between the O3 concentration level and the speed and direction of wind. Accordingly, the largest contributor toward high nighttime O3 ground level concentration in Kemaman was most probably NOx concentration.



Keywords: Long-term variations; NOx concentration; Nighttime ozone chemistry.



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