Fresh concerns over contract tracing tech on buses

Fresh concerns around contact tracing technology and its accuracy on Irish commuter buses have been raised by a new study carried out by two researchers at Trinity College Dublin (TCD).
Fresh concerns over contract tracing tech on buses
The Google/Apple API will be used in the Irish contact tracing app, and it is already being used in Switzerland, Italy and Germany. Stock image. Photographer: Simon Dawson/Bloomberg
The Google/Apple API will be used in the Irish contact tracing app, and it is already being used in Switzerland, Italy and Germany. Stock image. Photographer: Simon Dawson/Bloomberg

Fresh concerns around contact tracing technology and its accuracy on Irish commuter buses have been raised by a new study carried out by two researchers at Trinity College Dublin (TCD).

With contact tracing technology seen as critical for public transport, where strangers spend large amounts of time in an enclosed space together, reliable detection amongst devices might be impossible due to the radio environment inside a bus.

That is according to the independent ‘due diligence’ test carried out on the Google/Apple application programming interface (API) on Android handsets by Professor Doug Leith and Dr Stephen Farrell.

The Google/Apple API will be used in the Irish contact tracing app, and it is already being used in Switzerland, Italy and Germany.

"We found that the way the API measures Bluetooth LE signal strength, probably to save on battery power, can make it much more inaccurate at estimating proximity," said Prof Leith.

"We also found that updates to the API are silently pushed to handsets by Google, with no notification to users and no opt-out," he added. "This includes updates that can significantly affect contact tracing performance and, in turn, public health. This raises obvious concerns regarding oversight, and highlights the need for the governance of changes made by Google/Apple when it will eventually be deployed in Ireland."

The study also evaluated the technology and its proximity detection on a Dublin commuter bus.

"Contact tracing on public transport is an important use case as people can spend long periods together with complete strangers, making manual contact tracing extremely hard," Prof Leith said.

"We found that the radio environment inside a bus is highly complicated, presumably due to all the metal which reflects the radio waves. As a result, the signal strength can be higher between phones that are far apart than phones close together, making reliable proximity detection based on signal strength hard or perhaps even impossible.”

Prof Leith and Dr Farrell are currently working alongside the HSE and Department of Health in testing the technologies underlying the proposed contact tracing app. The HSE contact tracing app has yet to be released.

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