6. What can be done to reduce mercury releases?
- 6.1 What are the possible ways of controlling mercury releases?
- 6.2 What is the best overall approach to reduce emissions?
- 6.3 What further research and information is needed?
6.1 What are the possible ways of controlling mercury releases?
Mercury releases from natural processes, and from human
activity in the past, are largely beyond human control. Mercury
releases from current human activity may be limited by either
preventive measures or control measures.
Reducing the use of mercury-containing
products and raw materials containing unwanted mercury
impurities are examples of
- improving efficiency;
- using low-mercury fuels and alternatives, such as
natural gas instead of coal; and
- using fuels with a composition that makes mercury
easier to control.
Such measures are generally cost-effective, though sometimes
there could be negative effects. For instance, greater demand
for low-mercury fuel will lower the market price of high-mercury
fuel and – if not regulated – may encourage its use.
Replacing products and processes that contain
or use mercury with ones that do not is one of the most powerful
This may substantially reduce mercury in households, in the
waste stream and in the environment.
Such steps tend to be cost-effective, especially as demand
grows, but there are exceptions and possible trade-offs. Today,
for example, low-energy fluorescent lamps that contain mercury
may have a lower overall environmental impact than ordinary
bulbs, because less mercury containing fuel may be burnt to
generate the required electricity.
such as filtering exhaust gases, are
control methods at the point of emission. These
techniques are useful when raw materials contain tiny amounts of
mercury, that is in
fossil-fueled power plants,
cement production and metal mining and processing.
Control measures for other pollutants from coal-fired boilers
and incinerators can also reduce mercury emissions, although
their effectiveness depends very much on the type of coal, the
design of the boiler and the equipment used. Technology aimed
specifically at controlling mercury is being developed.
produce contaminated waste that could release mercury in the
future unless properly managed or re-used.
Effective waste management is another
control method which can reduce releases, for
instance from spills or gradual leakage (e.g. from broken
thermometers or auto switches and
Wastes containing low
concentrations of mercury
are generally permitted in normal landfills. In some cases, the
mercury content of the waste may first be rendered inert in
order to minimise release in the future. Sweden requires waste
with higher mercury concentrations to be deposited in specially
equipped landfills to limit leaching and evaporation, or in
‘final storage’ deep underground.
In some countries, the cost of waste management is high enough
to prompt producers to take preventive action and find
alternatives that do not produce mercury-containing
6.2 What is the best overall approach to reduce emissions?
A combination of both control and preventive measures is
required for optimum reduction of mercury releases.
Useful approaches for some of the main sources are:
- municipal and medical
waste incinerators may remove
mercury-containing waste before burning. Waste separation in
households and hospitals can be effective but costly.
Substitution with non-mercury products avoids this problem.
In the medium term, some mercury may also be removed from
- power-plant boilers, especially those
burning coal, may use less fuel or change to better
alternatives. Cleaning up the fuel before burning, or the
chimney gases after burning, can also help but the mercury
removed becomes a waste which needs to be managed;
- cement, mining and metal industries using raw
materials containing trace contamination may use a better
quality raw material or implement
- The scrap steel industry may separate
out mercury containing components, such as lights and
- small-scale gold miners may receive
training in safer methods using less or no mercury. Central
refining facilities could be provided for the miners. It is
difficult to enforce a ban;
- chlor-alkali producers
may apply strict mercury accounting procedures, leak
detection, exhaust air filtration and proper waste managemen
- mercury containing products may be
substituted with non-mercury products
- dentists may prepare mercury
amalgam fillings more
efficiently, use other materials instead or install amalgam
traps in the wastewater system;
- dental amalgams
may be removed before cremation or chimney
gases may be filtered. This may be avoided by switching to
non-mercury tooth fillings; and
- uncontrolled disposal of mercury-containing products or wastes
may be reduced by introducing and enforcing regulation and
improving access to suitable waste facilities. Substitution
with non-mercury products and processes may also
6.3 What further research and information is needed?
Many industrialised countries have addressed potential
problems caused by the use and release of mercury, with some
Some of the more common national initiatives include:
- environmental quality standards that
set maximum acceptable mercury
different media, such as drinking water, surface waters, air
and soil, and for foodstuffs like fish (in some countries);
- limits on the amount of mercury that
industrial, mineral and power generation operations can
release into the air and water, sometimes requiring the use
of ‘best available technology’ (in many countries); and
- restriction of mercury use in
specific products (in some countries).
Other actions have been taken, such as regulations on
recording and reporting mercury use and release by industry,
consumer safety measures, and advice on fish consumption.
Legal restrictions are complemented by the promotion of safe
mercury management. This includes developing and introducing
safer alternatives and cleaner technology, the use of subsidies
to promote substitutes and voluntary agreements with industry or
Because mercury crosses national borders, some regional and
international agreements have been reached to coordinate the
reduction of mercury releases.
For example, substantial reductions have been achieved by
legally binding agreements covering releases
across central and eastern Europe, Canada and the USA, and by
protecting the marine environment off the north-east Atlantic
and the Baltic Sea.
Various non-binding initiatives also cover
North America, the Arctic and Nordic regions, and the North Sea,
agreeing common goals, strategies and programmes.
In addition, several
voluntary private-sector initiatives supplement
national regulatory measures and help information exchange,
awareness raising and goal setting.
International trade in mercury chemicals and wastes is
restricted by two general multilateral environmental