The unique identifying numbers of over half a million smartphones have been recorded by a network of recycling bins in central London.
The data, which included the "movement, type, direction, and speed of unique devices", was recorded from smartphones that had their wi-fi on.
Although the Big Brother-esque rubbish bins are not harvesting data for an invasive totalitarian government, they are harvesting data. They're a proof-of-concept project, named Presence Orb, demonstrating the possibility for targeted personal advertising.
Targeted advertising is frequently sold to the public as a way to narrow down ads to fit personal user profiles - so you only see relevant information. But this can require knowing a fair amount about an individual, and could in fact reduce personal choice if you are bombarded with adverts that market research and some algorithm has decided are best fitted to you.
The idea is to bring cookie profiling into the real world, QZ reports.
Renew, the start-up behind the project, said the system provides an unparalleled insight into the past behaviour of users such as entry and exit points, "dwell" times, places of work, places of interest, and affinity to other devices. It should provide a compelling reach data base for predictive analytics such as likely places to eat, drink, and personal habits. Presence Orb is described as "a cookie for the real world".
In one of the most surveilled countries in Europe it is perhaps unsurprising such a project launched in Britain's capital.
In tests running between 21-24 May and 2-9 June, over four million events were captured, with over 530,000 unique devices captured.
Renew operates roughly 100 recycling bins around London, primarily in the City of London, which double up as digital advertising boards. Twelve of those bins were fitted with tracking devices.
If you don't want to be involved in the project, which many people are unlikely to know about, you can opt out by visiting the Presence Orb website which has instructions on how to prevent your phone's MAC address being picked up by the technology.
Nick Pickles, director of privacy campaign group Big Brother Watch, said: "This is shameless snooping for profit with absolutely no interest in respecting peoples' privacy.
"It is wholly wrong for companies we have absolutely no relationship with to turn our mobile phones into tracking devices without our permission or knowledge. If the Government did this there would rightly be uproar.
"I expect the Information Commissioner's Office to investigate this scheme urgently to address what is clearly a serious infringement on our privacy."