Assessing Air Quality Trends in Malaysian Conurbations: NO₂ and SO₂ Variability AcrossLand Use and Urban Activities

Nitrogen dioxide (NO₂) and sulphur dioxide (SO₂) are key urban air pollutants affecting air qualityand public health. While emission reduction policies aim to improve air quality, their spatialpatterns and long-term trends in conurbation areas remain uncertain. This study examines NO₂ andSO₂ trends in major Malaysian conurbations from 2019 to 2023, focusing on land use and urbanactivities. While conurbations are primarily urban, they exhibit diverse land use patterns, fromhigh-traffic commercial zones to industrial hubs, influencing air pollution differently. Continuousair quality monitoring data from Klang Valley, Johor Bahru, George Town, Kota Kinabalu, andKuching were analysed using statistical and geostatistical techniques to assess temporal and spatialtrends. Findings reveal that NO₂ concentrations are highest in traffic dense urban centres, whereasSO₂ levels are more prominent in industrial and port areas. Seasonal variations, including monsooneffects and transboundary haze, also influence pollution levels. The study highlights theheterogeneous nature of air quality trends across conurbations, emphasising the need for localisedair pollution control strategies. By integrating land use planning with targeted mitigation measures,policymakers can better manage urban air quality while addressing region-specific pollutionsources.