The start of the Cold War brought new foes and new fears for the officials running America’s biological weapons program. Determined to anticipate possible Soviet attacks, the U.S. staged more than 200 domestic tests aimed at assessing national vulnerabilities to biological warfare.

From the Pentagon to the Pacific
Ira Baldwin, Camp Detrick’s scientific director during World War II, left his position after the Allied victory in 1945 and returned to teaching at the University of Wisconsin. He continued to advise the government on issues concerning biological weapons, however, particularly the threat that might be posed by enemy spies releasing biological agents in American cities. In an October 1948 report, Baldwin posited that the U.S. was “particularly vulnerable to this type of attack.” But in order to determine the precise nature of these vulnerabilities, secret field tests would have to be done to ascertain the vulnerability of targets of potential interest to the enemy. The Army’s Chemical Corps, which ran Camp Detrick, agreed with Baldwin’s assessment and set up a Special Operations Division at Camp Detrick to carry out the tests. Its first target was to be the Pentagon.

In August 1949, the Special Operations Division operatives infiltrated the world’s largest office building and sprayed bacteria into the Pentagon’s air handling system, which then spread them throughout the structure.

The operatives moved to larger scale testing, releasing clouds containing supposedly harmless bacteria from Navy ships off Norfolk, Virginia, in April 1950, and the San Francisco coast in September 1950. The San Francisco experiments showed exposure among almost all of the city’s 800,000 residents. Had the bacteria released been anthrax bacteria or some other virulent pathogen, the number of casualties would have been immense.

The St Jo Program and Large Area Concept
The success of the first field tests only increased demand for more experiments. In response to an Air Force request, in 1953 the Chemical Corps created the St Jo Program and operatives staged mock anthrax attacks on St. Louis, Minneapolis, and Winnipeg. The bacteria were released from generators placed on top of cars, and local governments were told that “invisible smokescreen[s]” were being deployed to mask the city on enemy radar. The next stage was to increase dispersal patterns, dispensing particles from airplanes to find out how wide of an area they would affect. The first Large Area Concept experiment, in 1957, involved dispersing microorganisms over a swath from South Dakota to Minnesota; monitoring revealed that some of the particles eventually traveled some 1200 miles away. Further tests covered areas from Ohio to Texas and Michigan to Kansas. In the Army’s words, these experiments “proved the feasibility of covering large areas of the country with [biological weapons] agents.”

Airports and Subways
Serratia marcescens bacteria. Open-air testing continued through the 1960s, with the Special Operations Division operatives simulating even more audacious assaults. In 1965 they spread bacteria throughout Washington’s National Airport; a year later, agents dropped light bulbs filled with organisms onto the tracks in New York’s subway system. “I think it spread pretty good,” participant Wally Pannier later said, “because you had a natural aerosol developed every few minutes from every train that went past.” President Nixon’s 1969 termination of the United States offensive biological weapons program brought an end to the open-air testing, but the American public did not learn of this testing until 1977. Relatives of one elderly man Edward Nevin who had died of a nosocomial infection six months after the San Francisco tests sued the government in 1981, arguing that the supposedly harmless Serratia marcescens bacteria used in that test had in fact caused his death. In the event, the courts ruled against them, the main reason being that the plaintiffs could not prove that the bacteria used in the test were the same as those that killed Mr. Nevin.