alse positives in 2 ways: 1) By notifying Bobs only if they heard, say, 30+ min worth of messages, not just one message in passing. And 2) If the app <em>does</em> think Bob&#39;s been exposed, it can refer Bob to a <em>manual</em> contact tracer, for an in-depth follow-up interview.</p>

	<p>For other issues like data bandwidth, source integrity, and other security issues, check out <a href="https://github.com/DP-3T/documents#decentralized-privacy-preserving-proximity-tracing">the open-source DP-3T whitepa