This one comes from Wikipedia's article Mercury(II) chloride, which cites Susan Craddock, "City of Plagues":

Between 1901 and 1904 the Marines Hospital Service quarantined and engaged in an extensive disinfection program of San Francisco's Chinatown, forcing the closure of over 14,000 rooms and eviction of thousands of Chinese whose dwellings were rendered toxic and uninhabitable from the disinfection program. Long-term mercury pollution is still a concern for construction workers in Chinatown to this day.

I searched the Google item for "mercury" without seeing this, but I suspect it only searched from part of the book. The book doesn't have inline citations anyway.

The story seems plausible. The Marine Hospital Service was at the beginning of a transition to become the Public Health Service and did oversee quarantines. Shudderingly enough, mercuric chloride was an over-the-counter "disinfectant" at the time. The quote implies but doesn't actually say that this campaign was the reason for modern construction workers' exposure, but it seems all too likely if the rest is true. The quote suggests something extraordinarily awful and racist in that era, also highly believable. But what is the full story?

  • Do note that while mercury causes significant health problems, they are mostly long-term problems. When your other option is death by plague (penicillin wasn't even really identified until later and not available until much later), contaminating yourself with mercury sounds like a pretty good plan.
    – fectin
    Commented Jan 6 at 1:12

1 Answer 1


In a 17 block area, 16,888 rooms of 1,185 buildings had their walls and ceilings sprayed with a 1:800 solution of mercury bichloride.

Source: The Journal of the California Senate, 06 January 1903, at page 54.

The source explains which particular 17 blocks were sprayed.

However, Chinatown was completely destroyed by fire in April 1906, making the claim that there are still contaminated buildings unreasonable. Also, mercury bichloride was known as "corrosive sublimate" because it sublimes. In other words, it doesn't remain as a solid in open air for 100+ years, but instead dissipates into the air.

  • But is the mercury still a problem now? It would probably also be useful to know what the total number of rooms & buildings in that area was in the first place.
    – jwodder
    Commented Jan 5 at 20:26
  • @jwodder ok, I added more
    – DavePhD
    Commented Jan 5 at 22:57
  • Excellent find! This certainly clarifies the context (bogus diagnoses of bubonic plague) and describes a campaign which, to an uncritical reading, might not have been as sinister as first suggested. The sublimation of mercury dichloride (really the ionic nomenclature shouldn't have been used) is very relevant; nonetheless, to the degree that it actually reacted with anything, it could have been stabilized by forming organic mercury compounds. But no, that doesn't make it fireproof. :) Commented Jan 6 at 0:39
  • 1
    @MikeSerfas on the one hand, there were racist policies involved, as held by courts at the time in decisions like Jew Ho v. Williamson, 103 F. 10 (C.C.D.Cal.1900) casetext.com/case/jew-ho-v-williamson , but disinfection with mercury bichloride was a very standard practice at the time.
    – DavePhD
    Commented Jan 6 at 1:17
  • 1
    One should also note that by the standards back then, desinfecting a room with mercury bichloride did not make it uninhabitable or toxic. They used that stuff back than because it works as a desinfectant. The aftereffects of the mercury were either unknown or considered relatively irrelevant compared to the disease they wanted to get rid off.
    – quarague
    Commented Jan 12 at 10:12

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .