Gas leaks in buildings can present a serious threat to public safety, and even in less dangerous situations they can be costly and damaging to the environment. We’ve created an Internet of Things application that monitors gas pipes for leaks, and allows a building manager to remotely shut off a pipe if a leak is detected. This video will show you how to build it. An MQ9 gas sensor attached to a pipe will detect leaking gas, and will cause an alert to be sent to the building owner or manager using Amazon Web Services SNS. Then, using an iOS app and AWS SQS, the manager can stop the flow of gas through the pipe by remotely closing an electric solenoid valve.