Persistent organic pollutants that have accumulated in soils over decades can be remobilised by volatilisation. Clean air masses advected with the onset of the summer monsoon to India enhance revolatilisation of chemicals which have been banned for decades. During propagation of the monsoon northward across the subcontinent, the air is increasingly polluted by these secondary emissions. Remobilisation of some PCBs may even have reached a historical high, 40 years after peak emission.