Abstract

Air quality in Kuala Lumpur, Malaysia has been associated with various natural and anthropogenic sources and meteorological conditions. Air pollutants that show seasonal variations and frequently exceed the Malaysia Ambient Air Quality Standard (MAAQS) are particulate matter (PM) and surface ozone (O3), predominantly related to the monsoon seasons. Other air pollutants are usually associated with daily activities particularly related to the number of motor vehicles on roads, industrial activities and combustion processes. Haze episode due to biomass burning has been recognised as a major source of particulate matter in Kuala Lumpur. Potassium (K+), sulphate (SO42-), ammonium (NH4+), zinc (Zn), and iron (Fe) dominated the composition of inorganic substances in PM. Combustion from biomass burning during haze episodes also increased the concentration of carcinogenic substances such as polycyclic aromatic hydrocarbons (PAHs). Several organic molecules such as levoglucosan (1,6-anhidro-β-D-glucopyranose) have been identified as an indicator for biomass burning.

High surface O3 concentration is influenced by the chemistry of oxides of nitrogen (NOx) and volatile organic compounds (VOCs). VOCs namely benzene, toluene, ethylene and xylene (BTEX) were found recorded at the highest concentration near roadsides. The concentrations of major air pollutants were reduced during the COVID -19 lockdown except for O3.