Shanghai Burns a Ton of Dope Every Month in 1931

Here we see confiscated opium being burnt in Shanghai in 1931. I have read elsewhere that the special furnaces, overseen by the customs and police, were in Pootung (Pudong) and that convicted smugglers and other prisoners were used to do the job of hauling the dope into the brick built furnaces as part of their sentence. Apparently if the wind was in the right direction the sweet smell of the burning opium would waft across the Whangpoo into the International Settlement!!