What actually influences air pollution over the Indian Ocean?

Scientists from the Max Planck Institute for Chemistry detect substantial pollution of the atmosphere during periods between summer or winter monsoons

Using a combination of satellite observations and computer modelling, researchers of the Max Planck Institute for Chemistry have studied nitrogen oxides pollution over the Indian Ocean. They showed that the central Indian Ocean in the southern hemisphere is not always as pristine as found earlier during the winter monsoon period, but is polluted during the monsoon transition periods by pollution plumes from Africa and Southeast Asia. Generally, the most polluted region is the Bay of Bengal, which is influenced by Indian and south-east Asian outflow during most of the year and China during part of the year (Geophysical Research Letters, 30 April 2004 and 11 August 2004).