Structure and Composition of the Present-Day Atmosphere - Air Pollution and Global Warming: History, Science, and Solutions - page 69

Although Midgley also found that ethanol/benzene
blends reduced knock in engines, he chose to advocate
for tetraethyl lead, and it was first marketed in 1923
under the name ethyl gasoline .That year, Midgley and
three other General Motors laboratory employees expe-
rienced lead poisoning. Despite his personal experience
and warnings sent to him from leading experts on the
poisonous effects of lead, Midgley countered,

Despite the caution, more studies were not carried out
for thirty years, and effective opposition to the use of
leaded gasoline ended.
By the mid-1930s, 90 percent of U.S. gasoline was
leaded. Industrial backing of lead became so strong that,
in 1936, the U.S. Federal Trade Commission issued a
restraining order forbidding commercial criticism of
tetraethyl lead, stating that it is

...entirelysafetothehealth of (motorists) and to the
public in general when used as a motor fuel, and is not
anarcotic in its effect, a poisonous dope, or dangerous
to the life or health of a customer, purchaser, user or
the general public. (Federal Trade Commission, 1936)

The exhaust does not contain enough lead to worry
about, but no one knows what legislation might come
into existence fostered by competition and fanatical
health cranks. (Kovarik, 1999)

Between September 1923 and April 1925, 17 workers
at du Pont, General Motors, and Standard Oil died and
149 were injured due to lead poisoning during the pro-
cessing of leaded gasoline. Five of the workers died in
October 1924 at a Standard Oil of New Jersey refinery
after they became suddenly insane from the cumula-
tive exposure to high concentrations of tetraethyl lead.
Despite the deaths and public outcry, Midgley contin-
ued to defend his additive. In a paper presented at the
American Chemical Society conference in April 1925,
he stated that

Only in 1959 did the Public Health Service rein-
vestigate the issue of tetraethyl lead. At that time, it
found it

...regrettable that the investigations recommended by
the Surgeon General's Committee in 1926 were not
carried out by the Public Health Service. (U.S. Public
Health Service, 1959)

Despite the concern, tetraethyl lead was not regulated
as a pollutant in the United States until 1977. In 1975,
the catalytic converter, which reduced emissions of car-
bon monoxide, hydrocarbons, and, eventually, oxides of
nitrogen from cars, was invented. Because lead deac-
tivates the catalyst in the catalytic converter, vehicles
using catalytic converters could run only on unleaded
fuel. Thus, the use of the catalytic converter in new cars
inadvertently provided a convenient method to phase
out the use of lead. The regulation of lead as a crite-
ria air pollutant in the United States in 1977 due to its
health effects also hastened the phase-out of lead as a
gasoline additive.
Between 1970 and 1997, total lead emissions in the
United States decreased from 199,000 to 3,600 tonnes
per year, with only 13.3 percent of total lead emissions
in 1997 coming from transportation (U.S. EPA, 1998).
Today, the largest emission sources of lead in the United
States are lead ore crushing and smelting and battery
manufacturing. Since the 1980s, leaded gasoline has
been phased out in many countries, although it is still
an additive to gasoline in several others.

tetraethyl lead is the only material available which can
bring about these (antiknock) results, which are of vital
importance to the continued economic use by the gen-
eral public of all automotive equipment, and unless a
grave and inescapable hazard exists in the manufacture
of tetraethyl lead, its abandonment cannot be justified.
(Midgley, 1925b)

Midgley's claim about the lack of antiknock alterna-
tives contradicted his own work with ethanol/benzene
blends, iron carbonyl, and other mixes that prevented
knock.
In May 1925, the U.S. Surgeon General (head of
the Public Health Service) put together a committee
to study the health effects of tetraethyl lead. The Sur-
geon General argued that because no regulatory prece-
dent existed, the committee would have to find striking
evidence of serious and immediate harm for action to
be taken against lead (Kovarik, 1999). Based on mea-
surements that showed lead contents in fecal pellets of
typical drivers and garage workers lower than those of
lead industry workers, and based on the observations
that drivers and garage workers had not experienced
direct lead poisoning, the Surgeon General concluded
that there were “no grounds for prohibiting the use of
Ethyl gasoline” (U.S. Public Health Service, 1925). He
did caution that further studies should be carried out.

3.6.9.2. Concentrations
The U.S. National Ambient Air Quality Standard for
lead is 1.5 gm − 3 ,averaged over a calendar quar-

ter. Ambient concentrations of lead between 1980 and
2009 decreased from about 1.4 to 0.1

gm − 3 (U.S.
EPA, 2011c). The highest concentrations of lead are