Environmental Management: Principles and practice

Lead pollution
High lead levels in the air has been a problem for six or seven decades in some cities.
About 90 per cent of the atmospheric lead is probably from leaded petrol. Ice cores
from Greenland clearly show the pattern of pollution rising after the 1750s and
accelerating from 1925. Lead reduces birthweights and children are vulnerable as
they accumulate the metal and may suffer retarded mental development, especially
if exposed in the early years of life. Atmospheric lead may be compounded by drinking
water contaminated by old plumbing, and ingestion of white lead from old paint.
The poor are likely to suffer greater contamination. Some countries, starting in 1972,
have insisted on the use of non-leaded petrol. Such controls are not universal or
always enforced. Nevertheless, atmospheric lead in the UK has fallen from a peak in
1974 (and similar patterns can be seen in countries that banned leaded fuel).
Smogs
Between the 1860s and 1950s many UK and European cities had sulphur dioxide-
rich winter smog problems caused by domestic coal-fires. That problem has been
much reduced; however, there has been a world-wide increase in warm weather
nitrogen dioxide-rich (photochemical) smog, mainly caused by petrol-engine vehicles.
The 1956 Clean Air Act, the 1968 Clean Air Act, the 1974 Control of Pollution Act,
and a consumer shift to less polluting natural North Sea gas cured UK smogs (British
Medical Association, 1991:11).
Photochemical smogs are likely where there are sunny and still weather
conditions and traffic pollution, especially at high altitudes where there is less
shielding from UV (e.g. Mexico City or Madrid). Other emissions are caused by
vehicles in urban areas—partially burnt hydrocarbons including the dangerous volatile
organic carbons (VOCs) (which include toluene, ethylene, propylene, benzines, etc.),

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POLLUTION AND WASTE MANAGEMENT
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toxic dust, heavy metals (notably lead), and noise. VOCs are formed mainly from
diesel exhausts, cause respiratory diseases and may be carcinogenic; they also play
a part in tropospheric ozone production and acid deposition.
Pollution continues downwind of cities or busy road systems. A common
problem is tropospheric (the lower few kilometres of the atmosphere) ozone formed
from partially burnt hydrocarbons in vehicle exhaust or power-station flue-gases.
The WHO consider 60 ppbv of ozone to be dangerous to humans (the UN suggests
25 ppbv as a ‘safe limit’)—in 1992 Mexico City exceeded 398 ppm on more than
one occasion. Many other cities exceed safe ozone levels in hot still weather. Crop
damage from tropospheric ozone throughout the USA may amount to a 5 to 10 per
cent depression of harvest. A car manufacturer has recently introduced a radiator
catalyser which it hopes reduces ozone in the air passing the car, utilizing waste
heat to do so.
Air pollution from combustion-engine vehicles can be reduced by exhaust
catalysers, cleaner fuel (especially reduced sulphur and lead content), lean-burn and
direct-injection petrol engines, capture of evaporated fuel, non-polluting vehicles
(driven by electricity, natural gas, hydrogen, or fuel-cells), restrictions on use of
polluting private cars, such as road tolls for city driving or high parking charges and
other vehicle use restrictions, and improved public transport (Association of County
Councils, 1991). (Note that exhaust catalysers do not reduce carbon dioxide
emissions.)
In some countries (including the UK) total mileage travelled by car has increased
and markedly reduces the effect of better emissions controls. One or two cities have
tried restricting car use (environmental management goals may be pursued through
enforcement), for example by restricting cars with odd-numbered licence plates to
alternate days (the risk is that some will buy old cheap, polluting, even-number-plate
cars and increase emissions). Paris and some other French cities recently banned car
use in certain areas for days to encourage alternative transport use.
The problem of ocean pollution has been helped by new emission standards
for marine engines. It is also important to control disposal of lubricants, hydraulic
fluid and other harmful transport-related pollutants. What is needed in many countries,
including the UK, is a more foresighted and integrated approach to planning and
managing land use, transport and manufacture.