"At the University of California, Irvine, campus managers will keep an eye on how crowded buildings are, using a system that has been under development for years with a grant from the US Defense Advanced Research Projects Agency. As students’ phones and laptops search for Wi-Fi signals in buildings, they generate ‘probe events’ that will be used to estimate how many people are in each area. A dashboard alerts managers to overcrowding, which can then be addressed by putting up signs, moving furniture around or giving students a stern talking-to. In the future, students might also get an alert if they have shared space with a person known to have COVID-19. The system strips away IP addresses and other identifying info, but students who are still unhappy about having their data collected can opt out. Sharad Mehrotra, a computer scientist who leads the project, says it will help the university limit transmission of COVID-19. “When the pandemic started and things were locked down, the responsibility of handling the situation largely resided with the government,” says Mehrotra. “But as things open up, the responsibility shifts to the community. It shifts to individuals, but also to organizations. What roles organizations can play has not been settled yet.”"