Today I learned the very useful lesson that if you smell gas, you should call 911. I was only peripherally aware of a funny smell this afternoon before one of my neighbors waved me outside. My home office is in the living room, and I keep an eye on things outside while working but don't usually pay attention while I'm in meetings. My neighbor told me that she smelled something, I should call someone, and that she was going grocery shopping.
With that inauspicious comment, I googled my natural gas company and learned that calling 911 was the recommended action. And, in fact, when I called 911, they agreed. Fire trucks and the gas company quickly arrived. It turned out that the city, while replacing my street's sidewalks, had damaged my gas line, which filled my yard and started seeping into my front rooms.
So today I learned many fun facts: you should immediately call 911 if you smell something odd. Natural gas does not smell precisely like rotten eggs, unlike the advertisements. Firemen do not wear masks, even when they're in your house. However, the gas company is highly invested in making sure you don't blow up, and will even avoid walking on your tulips and raspberries while doing that.