A growing number of residents — particularly transplants from the East Coast — report developing persistent dry skin, irritated eyes, and brittle hair that only clears up when they leave the city. Not when they go somewhere humid, mind you. When they go anywhere else. Arizona. LA. Back home to New England. The symptoms vanish like a tech startup's Series A funding.

The easy explanation would be climate, but San Francisco is famously foggy and humid. That's what makes this so weird. One local resident who's battled eczema for years actually reported the opposite experience: "SF has extremely high humidity levels and as a lifelong sufferer of severe eczema it's the only place I've ever lived where my skin is not cracking." So we're not dealing with a simple dryness problem.

Some suspect the water. SF's tap water comes from the Hetch Hetchy reservoir and is generally considered excellent — it's one of the few things the city legitimately does well. But "great water quality" by EPA standards doesn't mean your particular biology agrees with the specific mineral content or treatment chemicals used. Chloramine, the disinfectant SFPUC uses, affects people differently than the chlorine used in many other cities.

Others point to environmental factors. San Francisco's microclimates are no joke, and neither is its mold and dust mite situation. As one resident bluntly put it: "There's lots of dust mites here too. And it gets moldy." Another Bay Area transplant reported sudden rosacea flare-ups that only appeared after moving here and disappeared on trips back East, saying, "There's definitely something in the air here."

So what's the takeaway? Nobody actually knows. And that's the frustrating part. We have a city government that spends $14 billion a year and employs thousands of public health officials, yet residents are left crowdsourcing dermatological mysteries online. Maybe before the next round of "wellness equity" grants, someone at DPH could investigate why a non-trivial number of people develop skin conditions that magically resolve at the airport. A shower filter might cost you $30. An answer from city hall? Apparently priceless — because it doesn't exist.