This lot really DO work at a snail's pace: Meet the mighty molluscs who monitor the pong at a Russian sewage plant

It's a snail-paced solution to pollution problems.

But a St Petersburg waterworks is putting six giant gastropods to work monitoring emissions from a sewage incinerator.

The African snails, the size of small rats, are attached to sensors that will show them getting sick if they take in too much bad air.

Mollusc maintenance: Six African snails fitted with heart monitors and sensors are being used to monitor pollution levels at a sewage treatment site in St Petersburg

Snail sewage? Three of the creatures breathe clean air, while three have air from the chimney at the incineration plant

Environmentalists have said the move is just a publicity stunt aimed at distracting attention from unsafe practices at the incinerator.

But the company, Vodokanal, said it was a serious attempt to improve control over what comes out of the smokestack.

The plant uses conventional gauges to check emissions, but company officials said it also wanted to keep an eye on compounds that might be produced in concentrations too low for the gauges to detect or that could harm humans if combined with other substances.

Olga Rublevskaya, director of wastewater disposal at Vodokanal, said: 'Live organisms won't deceive anyone about the danger of pollution.

'This is very strict control for us. Now we are under the watch of snails and crayfish all the time!'

Sensitive: The company behind the scheme, Vodokanal, also uses crayfish to monitor water pollution

Accurate: The snails become sick if the quality of air is too toxic and were selected because they have lungs and breathe in a similar way to humans

The company is also using crayfish to monitor the quality of city water.

The snails, which grow up to eight inches long, live in a fish tank inside the city's Southwest Waste Water Treatment Plant.

They are attached to sensors that measure their heartbeat and other vital signs. Three breathe clean air, the other three diluted air coming from the plant's chimney.

If the sensors register an unfavourable change in their behaviour and condition, it would be an immediate signal that air coming from burnt sewage residue was dangerous.

'The African snails, which are able to live for up to seven years, will also help to test the influence of possible accumulating substances over a long period,' said Sergei Kholodkevich, an ecological researcher who dreamt up the idea of using the creatures.

Mr Kholodkevich, who works at an institute of the Russian Academy of Sciences, said he chose snails because they had lungs and breath air 'like people do'.

Novel approach: The South-West Waste Water Treatment Plant in St Petersburg, where the snails live

But Dmitry Artamonov, who heads Greenpeace's St Petersburg office, accused Vodokanal of hiding information about the plant's effects on the environment.

'The issue is that the local treatment facilities are meant for treatment of domestic waste, but not for treatment of industrial waste that contains toxic substances and also gets dumped into the sewage waters,' he said.

'As for snails, it can be hard for them to indicate the environmental danger immediately, because such substances as dioxins, for instance, can accumulate in an organism over a long period of time and only decades later provoke cancer.'