Environment

Toxic Chemical Discovered in San Francisco's Fog

Fog rolling in off the Pacific brings iconic beauty to San Francisco, but scientists say it also carries with it something much less pleasant: toxic mercury. The fog along the coast of California deposits a neurotoxin called monomethyl mercury — at a concentration about 20 times that of rain — as it sweeps across the city. "On a relative scale, the levels of mercury are quite low and of no health concern. But it does bioaccumulate," or build up in organisms.