Sydney - It would be easy to teach dogs to help nab graffiti artists. They could be trained to alert handlers to the whiff of the aerosol spray paint cans used in defacing public property.

But popular targets like train stations and public parks are big places, and attacks often occur at night. Dog squads are simply too expensive an antidote to sprayers.

Science has come up with a technological solution that keeps costs down and, for good measure, do what dogs can't do and help police gather evidence for a possible prosecution.

Australian company E-Nose Pty Ltd, a specialist in providing equipment that monitors smells, has come up with diagnostics kit that can pick out the molecules in the vapour trail of graffiti artists and alert security guards to them.

"Our device will capture those molecules and set off an alarm," E- Nose chief executive Graham Bell said.

The electronic nose fits into a space the size of a tissue box and can be camouflaged to escape the attentions of vandals. From as far as 45 metres away, it can pick up the pong of a 4-second spray of paint.

When it detects paint molecules, the device relays a wireless message that can bring security guards scurrying to the scene of the attack. A bonus is that the detector can gather information that police could use to prosecute those snared during a graffiti attack.

It can tell the brand of paint and the time elapsed since its manufacture. (dpa)