Nest Protect may have returned to store shelves at a lower price point this week, but the smart smoke protector is also proving how sensors in homes provide invaluable data. Nest Labs has released a new report based on data from hundreds of thousands of Nest Protect devices. The anonymous data shows that carbon monoxide leaks are more frequent than many may have expected, and that at least one million households in the US, UK, and Canada are exposed to high levels of carbon monoxide each year. Around 400 people are killed by carbon monoxide poisoning every year in the US, so Nest’s data could help safety experts better understand why and when leaks happen.