Raising a stink

Air quality in poultry farms in Europe suffers badly due to ammonia from chicken droppings

Published: Tuesday 15 July 1997

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

Subscribe to Daily Newsletter :

Comments are moderated and will be published only after the site moderator’s approval. Please use a genuine email ID and provide your name. Selected comments may also be used in the ‘Letters’ section of the Down To Earth print edition.