A Review on Long Range Transport of Air Pollution in South Asia

Abstract

Long Range Transport (LRT) of air pollutants is an important process of pollution transport to very distant sites. In order to estimate sources of pollution and the possible impacts, it is necessary to understand local as well as long range transport of pollution. Such long distance and inter-continental transport of both natural as well as anthropogenic pollutants adversely affects different atmospheric processes. The South Asian region is severely affected by long range transport and transboundary pollution originated from Europe, Middle-east, Africa, Southeast Asia etc. which very much depends on the seasons. The transported mineral dust in west and south Asia contributes to high particulate loadings in the region. On the other hand, the forest fires in Southeast Asia lead to long-term climate implications. The transport of polluted continental air masses up to the Indian Ocean has implications for Indian Summer Monsoons (ISM). The LRT of acidifying substances has been found damaging for receptor site soils and sensitive ecosystems. The LRT is also a great threat to the sensitive ecosystems such as the Himalayan region and Western Ghats in the Indian subcontinent or South Asia. Furthermore, the continental outflow has been found to be rich in anthropogenic pollutants which get mixed with marine atmosphere and their deposition alters the C/N ratio of oceanic waters. The backward trajectories have shown that the downwind locations mostly suffer from bad air quality. The present study reviews the effect of LRT on rain, snow, and dust and aerosol chemistry and reiterates the need to calculate the fraction of transported pollutants from other regions while formulating the strategies to improve the air quality. There is a need of constituting a task force and regional cooperation which can look into the modalities of the calculations and policy framing between the stakeholders.