Residents in several US states are reporting a strange fog that emits a chemical smell, causing various health symptoms shortly after exposure. Starting in late December, symptoms include coughing, sore throat, and eye irritation. Experts have stated there’s no evidence linking this fog to any dangerous substances, attributing the occurrences to common winter respiratory viruses and natural moisture phenomena. Some speculate conspiracy theories, suggesting possible connections to experiments or chemical releases. The phenomenon has flooded social media with videos and alarming testimonials from eyewitnesses.