A third dimension by which special-purpose
health programs may be defined is by their
provision of special types of service. These pro-
grams are concerned with all types of persons
and with any type of disorder, for which the
service is provided. The list of such special ser-
vices is long; it results from the many subdivi-
sions of technology that have been developed
to diagnose and treat disease or to prevent it.

The numerous specialties of medicine and
the personnel engaged in them might be re-
garded as special types of service, but as a prac-
tical matter they contribute to general personal
health service. The programs that have en-
tailed special forms of organization are gener-
ally outside the domain of regular clinical
medicine. We consider here environmental
sanitation, emergency medical services, and
programs applying other special techniques.
Our perspective is the organized and not the
clinical aspects of these health services.

The tasks of controlling the environment so
that it is not harmful to human beings and is
conducive to health are tremendous. They in-
clude provision of safe water, disposal of
human and solid waste, reduction of air pol-
lution, insect vector control, protection against
ionizing radiation, and many other interven-
tions. Our main focus here will be on water
supply and sewage disposal.

After more than 200 years of economic devel-
opment, basic environmental protection ser-
vices in the industrialized countries have gen-
erally become well established. In the cities a
local unit of government, such as a Depart-
ment of Public Works, obtains and delivers the
water supply. Sometimes, in entrepreneurial
health systems, a private water company is
granted exclusive responsibility as a "public
utility" under contract with government.

The costs of original construction of water
supplies are usually derived from local general
revenues, but operating costs are usually recov-
ered from charges to water consumers. Contin-
ual surveillance of the quality of water deliv-
ered is generally a responsibility of the
Ministry of Health at local or higher levels.
Since urban populations have been growing
rapidly in the industrialized countries, there
are continual needs for acquiring new sources
of water. Chlorination or other forms of water
treatment, to ensure its safety, is routinely im-
plemented in urban water supplies.

Rural water supplies in industrialized coun-
tries may be through piped delivery in small
towns, but for isolated dwellings individual
wells are often necessary. Education and tech-
nical advice are the usual response of local
public health agencies to the needs of individ-
ual families.

Sewage disposal in cities of industrialized
countries is always a major challenge. The
sewer effluent usually goes into some river or
body of water, and the resulting contamina-
tion must be minimized. Accordingly, there
are sewage treatment facilities that should be
carefully maintained. These are operated by
various units of local government, with public
health agency surveillance.

Rural sewage disposal in small towns occa-
sionally may be handled by the piped method.
The effluent, however, is usually discharged in
some distant waterway without treatment. For
isolated dwellings, there may be sanitary la-
trines or indoor toilets, connected to septic

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