Mohamed Elnour YassenJamaluddin Md. JahiShaharuddin Ahmad2024-05-102024-05-102005Yassen, M. E., Jahi, J. M., & Ahmad, S. (2005). Evaluation of long term trends in oxide of nitrogen concentrations in the Klang Valley region, Malaysia. Malaysian Journal of Environmental Management, 6, 59-72.https://repoemc.ukm.my/handle/123456789/548Anthropogenic emissions of NOx account for a large majority of all nitrogen inputs to the environment. The major sources of man-made NOx emissions are high-temperature combustion processes such as those that occur in automobile and power plants. NOx contribute to a wide range of environmental effects directly and when combined with other precursors in acid rain and ozone. NOx react in the air to form ground-level ozone and fine particle pollution, which are associated with adverse health effects. Principally, and for a long time, transport vehicles and industrial emissions are the major sources of the pollutants emitted in the Klang Valley atmosphere. Following the increase of urbanization and industrialization, the amount of traffic has increased in the Klang Valley. Traffic is considered as the major source of NOx in the Klang Valley. Exhaust emissions from the petrol-powered motor vehicles include carbon monoxide, nitrogen oxide, hydrocarbons and particulate matter. A time series analysis of NOx monitoring data from six locations in the Klang Valley Region from 1997 to 2002 is presented. The aim of this study is to evaluate the variations and trends in NOx in the Klang Valley Region for the period 1997-2002.enJournal