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 quality
and public health. While emission reduction policies aim to improve air quality, their spatial
patterns and long-term trends in conurbation areas remain uncertain. This study examines NO₂ and
SO₂ trends in major Malaysian conurbations from 2019 to 2023, focusing on land use and urban
activities. While conurbations are primarily urban, they exhibit diverse land use patterns, from
high-traffic commercial zones to industrial hubs, influencing air pollution differently. Continuous
air quality monitoring data from Klang Valley, Johor Bahru, George Town, Kota Kinabalu, and
Kuching were analysed using statistical and geostatistical techniques to assess temporal and spatial
trends. Findings reveal that NO₂ concentrations are highest in traffic dense urban centres, whereas
SO₂ levels are more prominent in industrial and port areas. Seasonal variations, including monsoon
effects and transboundary haze, also influence pollution levels. The study highlights the
heterogeneous nature of air quality trends across conurbations, emphasising the need for localised
air pollution control strategies. By integrating land use planning with targeted mitigation measures,
policymakers can better manage urban air quality while addressing region-specific pollution
sources.