If you smell rotten cabbage in the next few days, be forewarned: It’s probably not your neighbor’s cooking.

On Monday, workers at the defunct Philadelphia Energy Solutions refinery in South Philadelphia were set to begin removing supplies of mercaptan, a colorless gas with an odor often compared with rotten eggs or cabbage.

Although it has other uses, mercaptan is used in the fossil fuel industry to give an odor to natural gas — the odor you’d detect at home if there was a possible gas leak.

The work is planned to last nine days.

The city’s Office of Emergency Management, which sent an alert, said mercaptan is not hazardous.

The owner of the refinery, then the largest on the East Coast, went bankrupt last year after the complex suffered a massive fire and explosion that led to its permanent closure. U.S. Bankruptcy Court in February approved the sale of the refinery complex to Hilco Redevelopment Partners LP of Chicago. The $252 million sale is set for closure in May.

Any residents who suspect that the odor they are smelling is the result of a nearby gas leak should still call 911.