<p>This study investigates the spatial and temporal variability of four key air pollutants; PM_2.5, PM₁₀, NO₂, and CO across Malaysia over four years (2018–2021) using data from 65 Continuous Air Quality Monitoring (CAQM) stations. Seasonal and regional differences were evaluated through boxplot statistical analysis, which captured the variability and distribution of pollutant concentrations under four climatic regimes: the dry (June–September), first inter-monsoon (April–May), wet (November–March), and second inter-monsoon (October) seasons. To visualise the spatial distribution of pollutants, Geographic Information System (GIS)-based interpolation was applied, while Principal Component Analysis (PCA) was employed to examine the multivariate relationships between pollutant concentrations and key meteorological variables, including wind speed (ws), relative humidity (rh), and temperature (Temp). Results revealed persistently higher pollutant levels in the Central and Northern regions, especially within the Klang Valley and Johor industrial corridors, where dense urbanisation and traffic emissions dominate. Lower concentrations were observed in the East Coast and Borneo, influenced by stronger maritime ventilation and lower anthropogenic activity. PM_2.5 and PM₁₀ were highly correlated (r &gt; 0.9), while moderate associations with NO₂ and CO indicated shared combustion sources. Meteorological variables exerted weaker but consistent modulation on pollutant dispersion, particularly under dry and inter-monsoon conditions. The integrated statistical–spatial–multivariate framework developed in this study provides a robust and reproducible basis for understanding monsoon-driven air-quality dynamics in tropical Malaysia and offers valuable input for regional forecasting and sustainable pollution management.</p>