The bad news is that it could get worse.

One of the latest frontiers of personal privacy – your nose - is about to be violated, New Scientist says.

In the likely store of the future, an "air cannon" will track you as you walk around and then puff a smell at your nostrils –fresh coffee, luxury perfume, newly-baked bread, grilling meat, for instance - in the hope of prompting you to make a purchase.

Invention

The "cannon" was invented by scientists at the Advanced Telecommunications Research Institute in Kyoto, Japan, the British science weekly reports in next Saturday's issue.

The initial idea was to provide evocative smells for people exploring virtual-reality environments, such as someone driving a car simulator.

But marketing wizards are likely to latch on to the device to try to tempt shoppers towards a counter, their noses twitching and their wallets ready, the report says.

The gadget comprises a jet that forces a smell-laden vapour into a chamber, where it is compressed by a diaphragm and then forced down a fine nozzle towards the target.

Pinpoint

It is so accurate, according to its inventors, that it can target a single individual while someone just 50cm away will smell nothing.

The aiming is directed by a camera, which follows the target's eyes and delivers a sniper's shot of smell a couple of centimetres lower in order to place the molecules right under the nose.

The system faces technical, ethical and legal obstacles, however.

Among everything else, some people might be allergic to the scents and customers may rebel against the olfactory subliminal advertising.