According to San Francisco's Public Utilities Commission, a lamp post that toppled over and nearly crushed a driver had been terminally compromised by a most deadly combination: human and dog urine.

KTVU reports that the three-story-tall pole snapped and fell onto an occupied car at around 6:30 p.m. Monday night, (though commenter Shaqapopolis says the event actually occurred Sunday) at the Nob Hill intersection of Pine and Taylor.

Luckily, the driver escaped injury, and was just shaken up by the experience. But why did the structure fall in the first place?

A PUC spokesperson acknowledged that the light was old, but said that it wasn't just age that felled the massive pole, it was pee. Lots and lots of pee.

“We believe there was some contribution of dog or human urine on the base of the pole,” PUC spokesman Tyrone Jue told the Chron, saying that pee "accelerates the corrosion of the metal base of street poles."

“The base or the bottom of the pole was rusted out and that contributed to the pole falling down,” another PUC spokesperson, Charles Sheehan, told KTVU.

This is the fourth light pole to unexpectedly collapse in San Francisco in the last two years, KTVU reports, saying that one fell on Greenwich Street, and two went down on Guerrero. The latter incidents caused the PUC to "replace 160 poles on Guerrero Street as a result."

That's not the only area that's undergone a massive replacement: according to the Chron, the PUC just started a program where workers visually check every one of San Francisco's 25,000 light poles, causing the replacement of 100 more along San Bruno Avenue.

But even then, it might be time to stop letting Rover (or yourself) pee on the local light poles. Since it appears the PUC has yet to get their hands on the DPW's pee-repelling paint, Jue has some ideas of where to go, instead.

“We encourage people and dogs alike to do their business in other places, like a proper restroom or one of our fire hydrants, which are stronger and made out of cast iron."

We're sure the SFFD will thank him for that one.