China is about to unleash a new weapon in the battle against illegal polluters - humans trained to sniff out foul gases, according to Chinese media.
Pollution sniffing is said to be "quite unpleasant"
The southern city of Guangzhou will be patrolled by "professional noses" who will detect unlawful emissions from factories, the China Daily reported.
The "noses", a trade more often linked with the perfume industry, have been trained by environment experts.
Liu Jingcai, of the sniffing team, said the work was "quite unpleasant".
"We have to stay in a lab smelling those awful gases repeatedly," he said.
The team, from the Panyu environment monitoring station, will use technical equipment to monitor gas density and use their noses to gauge its harmfulness.
"Our equipment can accurately analyse the density of a particular gas - but with mixed gases they are not reliable and it cannot tell the effects on humans," Mr Liu told the China Daily.
Mr Liu said they had "honed smelling skills from various sources of pollution".
"Now we can differentiate between hundreds of smells that may make people ill, before making an assessment on their density."
Mr Liu and his team expect to be issued certificates allowing them to officially start their careers as professional noses.
The China Daily said the certificates are valid for three years at a time, because human's sense of smell deteriorates with age.
They expect to target rubber factories, oil refineries and rubbish dumps.