While “Dusty Rain” may be a great name for a country western singer, it’s not something you want to find covering your car, your house and everything else outdoors. That’s why residents of parts of Oregon, Washington and Idaho in the northwestern U.S. were concerned over the weekend when a mysterious dusty rain falling from the sky looked like a white, chalky liquid and not the usual mist that drives then into the coffee shops. Fortunately, it may have had a natural, although not necessarily harmless, cause.

Milky rainwater collected from a rain gauge after the storm

The milky rain was filled with whitish particles which led some analysts to speculate it was caused by ash from the Volcano Shiveluch in Kamchatka Krai, Russia, which erupted in late January, sending plumes almost 33,000 feet into the air. Mexico’s Colima Volcano is also very active, with 14 eruptions in one day in early February. There was also a recent wildfire on the California/Nevada border that was a possible suspect. Without an official and/or plausible explanation, theories of alien intervention, bomb testing, industrial accident and other non-conventional causes arose.

The fact that the volcanoes were so far away and occurred so close in time to the dusty rain made them improbable causes. A more likely culprit was a dust storm in Nevada. It happened about 12 hours before the milky rain began to fall, perfect timing for 40 mile-per-hour winds to carry the dust kicked up to Spokane, Washington. The projected trajectory seemed to match the path that the milky rain fell on through the states.

White substance left on a truck after the rain evaporated

Case closed? Not so fast. Experts are still checking radar images and mineral tests of the residue to confirm the origin as the Nevada dust storm. Is it safe to go outside? Well, water from the ubiquitous Pacific Northwest rains is clear now. The residue probably isn’t harmful to touch, but be careful cleaning the grit from cars and other painted surfaces. And don’t go drinking it. And make sure you wash any fruit or vegetables that may have been covered with it. You probably shouldn’t breath the dried residue either. And …

In other words, no one knows for sure. What do you think?

While you’re pondering the dusty rain, here’s a Dusty rain song.