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Of the world’s 20 worst cities for air
pollution, 14 are in India. In Delhi, thick
smog in November 2017 reduced the
air quality to the equivalent of smoking
50 cigarettes a day.no sanitation. The Thames River,
in London, was both the source
of water for domestic use and the
outlet for untreated human sewage.
Disease spread, river fish were
wiped out, and the smell was
sometimes unbearable. Other urbancenters fared little better: similarly
unsanitary conditions were recorded
in Berlin in 1870, for example.
In the United States, the first two
cities to enact laws to ensure clean
air were Chicago and Cincinnati, in- By that time, the manure from
3 million horses pulling wagons in
North American cities was seeping
into water supplies and producing
plagues of disease-causing flies.
As horses were gradually replaced
by the internal combustion engine,
smog from cars and trucks became
a major issue. London’s Great Smog
of 1952, described as a “pea-souper”
for the color of the filthy air, killed
more than 4,000 people.
Air pollution
The result of harmful substances
being released into the atmosphere,
such as gases or small particles
called aerosols, air pollution can
have natural sources, such as
volcanoes or wildfires, but is mainly
caused by human activity. The main
air pollutants are emissions ❯❯THE HUMAN FACTOR
See also: Pesticides 242–247 ■ Acid rain 248–249 ■ Light pollution 252–253 ■ A
plastic wasteland 284–285 ■ The water crisis 286–291 ■ Waste disposal 330–331 The “Great Stink”
By the early 19th century,
London’s Thames was the
most polluted river in the
world. Industrial pollution and
human effluent emptied into
it from thousands of drains.
People complained, but the
government did nothing. In
1855, the scientist Michael
Faraday lambasted politicians
for their inaction, to no avail.
However, they got the message
three years later, when a hot
summer contributed to the
“Great Stink” of 1858. The
Houses of Parliament, being
adjacent to the Thames, were
badly affected, and legislation
was suddenly enacted in a
mere 18 days.
Civil engineer Joseph
Bazalgette was commissioned
to design a new sewage
system. It was based on six
interceptor sewers, 100 miles
(160 km) long, which flowed to
new treatment works. Most of
London was connected to
it within a decade. Much of
the sewage system is still in
operation today, more than
150 years later.This cartoon, published in Punch
magazine in July 1858, was entitled
“The Silent Highwayman.” People
at the time attributed the spread
of cholera to the bad river smells.Air pollution control
systems still lag behind
economic development.
Bob O’KeefeUS_230-235_Pollution.indd 233 12/11/18 7:47 PM