Rapidly rising transboundary atmospheric pollution from industrial and urban sources in Southeast Asia and its implications for regional sustainable development

Transboundary atmospheric pollution is a major concern throughout much of Southeast Asia (SEA), although most attention has, to date, focused on episodic haze events associated with biomass burning in the region. Here, we reconstruct long-term variations in transboundary inputs of chromium (Cr), an industrial pollutant, to Singapore over the period 1900-2017 by adopting a novel catchment-reservoir mass balance methodology that combines a national emissions inventory and a paleolimnological approach. Results show periods of low (before the 1950s) and relatively stable (the 1950s-1980s) levels of transboundary Cr deposition in Singapore followed by an unambiguous increase fromca.1990 onwards, most likely linked to the onset of rapid industrialisation in neighbouring parts of Malaysia and Indonesia. Notably, fromca.2000 onwards, fluxes of transboundary Cr deposition in Singapore further increased by 3% per year, almost doubling from 6 +/- 3 tonne Cr yr(-1)in 2000 to around 11 +/- 3 tonne Cr yr(-1)in 2017. This post-2000 rapid increase may reflect the effects of globalisation, pro-export driven economic growth policies and increasing capital inflows to the whole region, including from Singapore, all of which combined to drive industrialisation throughout much of SEA. The current trend of increasing transboundary pollution from anthropogenic activity highlights an urgent need for effective collaboration among countries in SEA in order to improve well-being and help guarantee sustainable development throughout the region.