Use a LPG detector to periodically monitor the gas level and send alerts using Amazon SNS to subscribed email ids.
This projects shows a simple environment monitor which sends you an EMail when an abnormal weather condition is detected.
Idea is to use AWS IoT button as a switch when pressed sends notification to the homeowner that someone has tried to enter the home.
Nowadays the temperature is rising due to global warming, and we gotta keep track of it. This small application does it for you.