Ground-Level Ozone Pollution in Malaysia: Descriptive Analysis and Classification Using Hierarchical Clustering

Tropospheric ozone, a critical air pollutant, plays a significant role in determining ambient air quality. It forms through a photochemical reaction between sunlight, volatile organic compounds (VOCs), and nitrogen oxides, earning it the label of a secondary pollutant. Beyond its impact on human health, ozone also poses a threat to the environment and vegetation. This study hourly average of ozone (O3) concentrations in 2022 across 46 air quality monitoring stations in Malaysia. Mean, standard deviation, skewness, and kurtosis were employed to understand the characteristics of ground-level ozone concentrations. Using Agglomerative Hierarchical Cluster analysis, the stations were grouped into three clusters based on the mean hourly average O3 concentrations: High Pollution Region (HPR), Medium Pollution Region (MPR), and Low Pollution Region (LPR). Interestingly, some suburban stations, typically expected to have lower pollution levels, recorded higher O3 readings and were categorized in the high pollution cluster. By clustering the monitoring stations into these three groups, future research can benefit from a more focused assessment of air quality, reducing the complexity of monitoring and enhancing the effectiveness of pollution management strategies.