Anionic Surfactants and Traffic Related Emission from an Urban Area of Perak, Malaysia

Anionic surfactants are one of the pollutants derived from particulate matter (PM) and adversely affect the health of living organisms. In this study, the compositions of surfactants extracted from PM and vehicle soot collected in an urban area were investigated. A high-volume air sampler was used to collect PM sample at urban area based on coarse (> 1.5 µm) and fine (< 1.5 µm) mode particles. Meanwhile, the vehicle soot was collected randomly from the exhaust pipe of various types of diesel and petrol vehicles using a soft brush during dry days. The concentration of anionic surfactants, such as Methylene Blue Active Substances (MBAS), was determined by the colorimetric method using UV-Vis Spectrophotometer. Morphological properties of the PM and exhaust soot sample was studied using field-emission scanning electron microscope. Results revealed that the MBAS concentration was dominated by fine mode particles (6.03 ± 3.97 µmol g^-1), whereas heavy-duty vehicles, such as buses, demonstrated the highest surfactant concentration with an average value of 0.340 ± 0.180 µmol g^-1. The structure of collected PM for all samples mostly appeared to be an irregular shape with the size range of ultrafine particles (0.05-0.2 µm). The emission of surfactants from diesel and petrol vehicles, especially at urban areas, should be a major concern, because they could negatively affect human health and the environment.