Air pollution in Malaysia: current understanding and future directions

Air pollution remains a significant environmental and public health issue in Malaysia, with notable effects on the economy and climate. Despite long-standing monitoring systems and regulations, comprehensive assessments that combine multiple data sources with health impact analysis are still lacking. This study reviews peer-reviewed studies, haze events from 1983 to 2024, regulatory documents from the Department of Environment, Malaysia, and data from air quality monitoring stations across regions. and presents an integrated assessment of air quality across strategic and important urban, industrial, coastal, and residential areas. It analyses trends in the Air Pollutant Index and PM_2.5 levels from 2013 to 2024, and uses exposure-response models to estimate related deaths and economic impacts. Satellite data (MODIS and AERONET) help understand spatial variation and cross-border pollution. Average PM_2.5 levels ranged from 8.66-16.77 µg/m³, consistently above WHO guidelines from 2021. In 2020, PM_2.5 exposure was linked to 1.419 early deaths in four urban areas, costing about MYR 2.46 billion (USD 524 million). Population-attributable fractions ranged from 2.6-7.1%, with risk rising by 2.7-7.6% per 10 µg/m³ increase. The study identified 12 major haze events, notably in 1997 and 2015. COVID-19 restrictions temporarily reduced emissions, but levels quickly rebounded afterward. Conclusively, Malaysia's air quality issues are mainly due to transport, industry, dust, and recurring transboundary haze. Solutions include better source tracking, enhanced secondary pollutant monitoring, integrating health data more effectively, adopting advanced technologies, and aligning policies with WHO standards. Pollution effects are more pronounced in metropolitan regions due to proximity to dense sources.