Ezahtulsyahreen Ab. Rahman1,2, Firdaus Mohamad Hamzah This email address is being protected from spambots. You need JavaScript enabled to view it.3, Mohd Talib Latif4, Doreena Dominick5,6 

1 Department of Chemical and Process Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia
2 Air Division, Department of Environment, Ministry of Environment and Water, 62574 Putrajaya, Malaysia
3 Department of Engineering Education, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia
4 Department of Earth Sciences and Environment, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia
5 Centre for Atmospheric Chemistry, University of Wollongong, Wollongong, NSW 2522, Australia
6 School of Earth, Atmospheric and Life Sciences, University of Wollongong, Wollongong, NSW 2522, Australia

Received: August 28, 2021
Revised: November 20, 2021
Accepted: December 5, 2021

 Copyright The Author(s). This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are cited.

Download Citation: ||https://doi.org/10.4209/aaqr.210161  

Cite this article:

Ab. Rahman, E., Hamzah, F.M., Latif, M.T., Dominick, D. (2022). Assessment of PM2.5 Patterns in Malaysia Using the Clustering Method. Aerosol Air Qual. Res. 22, 210161. https://doi.org/10.4209/aaqr.210161


  • PM2.5 concentrations were classified into three regions, HPR, MPR and LPR.
  • Haze episode contributes to high PM2.5 concentrations.
  • Monsoon phenomenon influences the monthly variation trend of PM2.5.
  • PM10 and CO were significantly correlated in all regions.


Particulate matter is the parameter of most concern in air quality monitoring in Malaysia. This study discusses the variations and clustering of PM2.5 recorded from 2018 to 2019 at 65 stations of the Continuous Air Quality Monitoring Network of the Malaysian Department of Environment. PM2.5 concentrations were recorded continuously using a tapered element oscillating microbalance. The cluster analysis was conducted using the Agglomerative Hierarchical Cluster (AHC) method. The results show that the daily average of PM2.5 concentrations ranged between 8 and 31 µg m–3. The cluster regions were classified into High Pollution Regions (HPR), Medium Pollution Regions (MPR) and Low Pollution Regions (LPR) based on the AHC analysis. The mean concentration of PM2.5 recorded in HPR was significantly higher with 23.04 µg m–3 followed by MPR and LPR. The results also showed that the highest concentration of PM2.5 was recorded during the 2019 haze episode for all three regions, with the air pollutant index indicating very unhealthy and dangerous levels.

Keywords: PM2.5, Regional concentration, Agglomerative hierarchical cluster

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