AUSTIN (KXAN) — If you’re smelling something strange in the outside air around Austin, the Austin Fire Department doesn’t want you to be alarmed or call 911.

The natural gas-like smell is coming from the Luling oil fields and it’s common for this time of year, according to fire officials.

The odor from the oil fields can be smelled in the area when the south winds return after a cold, still night. The sulfur smell collects at the ground instead of dissipating like normal, so in the morning the wind brings up the smell and it spreads across the city, AFD says.

AFD says it has received over 100 calls for the odor this year, but there is no need to call 911 for general outdoor odors. However, if you’re smelling natural gas inside your home, you should call 911.

In recent years, AFD has received reports of the Luling smell from south Austin to Pflugerville.