In 1923, William Mansfield Clark from the U.S. Department of Agriculture alerted the public to the dangers of tetraethyl lead in gasoline, and further field studies, conducted by James P. Leake, set the standards for the safe level of lead in gasoline.

In October, 1922, Clark warned that “on busy thoroughfares it is highly probable that the lead oxide dust will remain in the lower (atmospheric) stratum,” and can constitute a “serious menace to the public health.”