Residents in Southern California on Monday were greeted with pungent smells of sulfur.

Officials have been perplexed.  An explanation being explored is a wind delivered odor from a recent large scale fish die off in the Salton Sea.

Residents of Riverside County through to the San Fernando Valley were the recipients of the odor, about 150 miles from the Salton Sea.

Experts however are skeptical of this explanation.

Jack Crayon, who is an environmental scientist with the Department of Fish and Game in California says that this odor development around the sea is common, it occurs a few times a year and that it is unusual for the odor to travel that kind of distance.

Source Salton Sea eyed as culprit of big stink in Southern California | Fox News.