"This is part of the findings of a Swiss student of the Hochschule Rapperswil (HSR) who studied the status of waste incineration in China ... This work revealed that the heavy metal levels in the residue from the municipal waste incinerators are clearly much lower than those in Switzerland. One exception is mercury; its relatively high levels in the slag leaves room for interpretation and speculation. Because of the data that was collected, we cannot exclude the possibility that some Chinese municipal waste incinerators might even emit mercury into the environment." (Quoted from paper)