Case Study in Peninsular Malaysia - Where Does PM2.5 Come From?
PM2.5 is particulate matter with size less than 2.5 microns (0.0025 mm) which can be consisted of a mixture of chemical including carbon, organic matter, or even heavy metal released directly from a source or as a by-product of chemical reactions. Even though there is no standard air quality guideline focusing on the concentration of PM2.5 in Malaysia, it has been studied extensively especially in urban areas as these fine particles can easily invade human's respiratory system, leading to health issues and death.
In order to investigate the concentrations and sources of PM2.5 in the air of Malaysia, a study was carried out by researchers from UKM and USM by filtering the air in 3 study locations that represented urban, suburban and rural areas, followed by investigating the content of the particulate matter (or commonly known as dust) collected in the laboratory. The results shown were predictable: the highest concentration of PM2.5 was found in the urban area, followed by suburban and rural areas as shown in the bar chart below with the unit measurement of microgram per cubic meter of air (ug/m3). Comparing the results to the United States Environmental Protection Agency (USEPA) National Ambient Air Quality Standard and World Health Organisation (WHO) PM2.5 Air Quality Guideline, only the PM2.5 concentration in urban area exceeded the USEPA National Ambient Air Quality Standard due to the heavy traffic compared to suburban and rural areas.
The sources of PM2.5 were determined according to the chemical found in the particulate matter collected. For examples, several heavy metals with ammonium indicated that the source was motor vehicle emission and soil dust while magnesium ion and chloride indicated that the source was sea spray. Besides, sodium and calcium ions indicated that the source was mineral dust. From this data analysis, there were 3 major categories for sources of PM2.5 for each study area as shown in the pie chart below. The main sources of PM2.5 for urban, suburban and rural areas were motor vehicles or soil dust, domestic waste combustion and biomass combustion respectively. Even though the main sources of each location were different, there were two similarities:
- High levels of sulfate and nitrate as a result of motor vehicles and industrial activities.
- High levels of traffic-related zinc and iron compared to other metals
Since the main sources of PM2.5 in Malaysia were anthropogenic (man-made) activities such as traffic emission and open burning, actions can be taken to improve the air quality through the implementation of a better air pollution management policy. At the same time, more data should be collected for a more accurate and precise analysis.
Ooi, E., Mustaffam, N. I. H., Amil, N., Khan, M. F. & Latif, M. T. (2015). Source contribution of PM2.5 at different locations on the Malaysian Peninsula. The Bulletin of Environmental Contamination and Toxicology. DOI 10.1007/s00128-015-1477-9
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