Many mysteries exist to boggle the mind at any given moment, but it’s not every day that an unknown odor boggles noses across entire cities.

On the evening of Tuesday, Sept. 24, emergency dispatchers in Southwest Washington started receiving reports from residents about strange odors. People described smelling something reminiscent of sulfur, natural gas, or propane; others complained of burning garbage, ammonia, or “sewage broccoli.”

Not pleasant aromas by any stretch of the imagination.

Based on public reports, officials determined the noxious cloud started somewhere in the Kelso area before drifting south into Clark County. A breeze out of the north/northwest pushed the scent down the I-5 corridor, covering communities one after the next from Woodland to Vancouver. Like a fog, it rolled over the Columbia River and into parts of Portland around midnight. Some people said the scent caused headaches, eye and throat irritation, and disrupted sleep.

So… what was it?

Officials from multiple agencies, including local, state, and even federal organizations, jumped into action to pinpoint the source of the stench. The Cowlitz County Department of Emergency Management said air monitors didn’t detect any abnormal gas readings. Gas pipelines were functioning normally, railroad operators had zero leads, and no ships passed through the Kalama area at the time.

Other theories, according to the Cowlitz County fire district, had nothing to do with potential human mishap. Did the Earth shake? Did Mount St. Helens let out a belch? We can all breathe an odorous sigh of relief — the Cascades Volcano Observatory reported no abnormal activity or readings.

Up in the air

As of Wednesday night, the source of the stench had not been determined.

Folks who notice the smell are advised to stay inside and keep their windows closed — anyone experiencing adverse reactions should call 911, Cowlitz County officials said. Keep an eye on Facebook for updates.