Air quality in poultry farms in Europe suffers badly due to ammonia from chicken droppings
EUROPE'S farm buildings have concentrations of ammonia, bacterial toxins
and dust, high enough to harm both farm
workers and animals. Roger Phillips of
the Silsoe Research Institute, Bed-
fordshire, has reached this conclusion
following a four-year study for the
European Commission of farm buildings
in Britain, Denmark, Germany and
the Netherlands (New Scientist, Vol 154, No 2078).
Cocktails of ammonia, dust and
bacterial toxins can make farm workers
wheeze and cough, or contract a flu-like
condition called toxin fever. Animals
become susceptible to infection and
their growth is inhibited when exposed
to pollutants. The study group found
that the air was least wholesome in
buildings used for rearing poultry, especially broiler houses where chicks aie
fattened for around seven weeks before
being slaughtered. Air in buildings
where cattle were reared seldom
breached safety limits.
The researchers found that airborne
levels of ammonia frequently exceeded
the recommended safe level of 20 parts
per million for animals, or 25 parts per
million for people, in both poultry
houses and piggeries. The highest single
concentration measured - 73 parts per
million - was at a Dutch battery farm.
Poultry farms have a particular problem
with ammonia because bird droppings
are rich in nitrogen. Bacteria convert
urea and uric acid in the droppingg into
ammonia.
The average airborne ammonia in
British broiler houses was 27 parts
per million. The corresponding Dutch
and Danish figures were I I and 8 parts
per million. German poultry houses
averaged 21 parts per million of ammonia. Dust levels were highest at poultry
farms too, with the average value
exceeding the recommended safe dose
for animals.
On the same farms, average concentrations of bacterial toxins approached
800 nanograms per cubic metre of air.
The corresponding figures for cattle and
pigs were just 15 to 140 nanograms per
cubic metre respectively. No official safe
limit exists for concentrations of bacterial toxins, although a provisional safe
dose of 500 nanograms per cubic metre
of air was proposed a decade ago by
Ragnar Rylander, a researcher with
Sweden's Department of Environment
Hygiene, Gothenburg.
Phillips says research is urgently
needed into ways to improve air quality,
particularly on poultry farms. For
egg production, one possibility is to
adopt Dutch and Danish designs for
battery cages where droppings fall onto
a moving belt beneath. This keeps
the droppings dry, which makes it
more difficult for bacteria to break
down the urea into ammonia. Broiler
chickens are usually kept on stone
floors covered with sawdust. Cutting
pollution would mean using more
sawdust to absorb moisture or reducing
the number of birds that are kept in a
given area, both of which would eat into
farmers' profits
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