Apple and Google, which control the world’s most popular smartphone operating systems, gave a first look Monday at how public health apps will alert you if you’ve been exposed to the coronavirus.

The two tech giants have been working on new contact tracing tools for public health organizations that can tell you if you’ve crossed paths with someone who later tests positive for the deadly virus.

How it works: The new COVID-19 tools on iPhones and Android devices will use Bluetooth to sense nearby smartphones. When you’ve tested positive, you enter the test result into the app.

With your consent, anyone who was near you over the past 14 days will get a push notification that they have been potentially exposed: “You have recently come into contact with someone who has tested positive for COVID-19. Tap for more information.”

Public health authorities have used contact tracing for years to interview infected people, learn who they’ve been in contact with and advise them on what to do.

The smartphone version could help authorities more quickly lift social distancing constraints or respond to a new outbreak.

Participation is voluntary. Effectiveness of smartphone contact tracing hinges on how many people choose to use it.

Privacy advocates warn the technology being developed is potentially invasive and raises important questions of how to safeguard people’s sensitive health information.

Apple and Google say they’ve taken precautions to make sure tracking data is anonymous and they say apps will not be permitted to track your specific location.

In a blog post Tuesday, security firm FireEye said apps should think through the privacy and security implications when tracking users to help halt the spread of COVID-19:

 Apps should explain what data they collect and should outline under what conditions that data will be shared with third parties.

 Data should be kept secure, possibly through the use of encryption.

 In certain jurisdictions, users have the right to request access to the data that has been collected and can request that it be deleted. Apps should be prepared to comply with those requests, FireEye said.