III. AIR POLLUTION

It is rare for fish processing operations to cause air pollution which is dangerous to health, but they can cause unpleasant smells and an unpleasant environment. Fish meal plants are one of the main producers of unpleasant smells which, although harmless, may lead to complaints from the neighbouring population. To reduce odours as much as possible, raw material for fish meal production must be as fresh as possible, and processing should begin as soon as the raw material arrives at the factory. The main contribution to the odours associated with fish meal production comes from the cooking and, particularly, the drying stage. Commercial equipment is available for odour reduction which involves the passing of vapours through water (scrubbing) and/or the burning of the vapours. The efficient operation of this equipment requires that the quantity of vapour is kept as small as possible and that the ducts and flues carrying the vapour are kept in good condition in order to prevent any vapours from escaping. A detailed guide to the efficient management of a fish meal plant so that air pollution is kept to a minimum is given in Torry Advisory Note No. 72 (Anon).

Other methods of fish processing can cause unpleasant smells even when processing is undertaken at a relatively small scale. The main processes include smoking and sun drying. With smoking operations, however, relatively small quantities of usually not unpleasant woodsmoke are produced which are seldom a cause for complaint from the surrounding population. With sun drying, on the other hand, the smell generated during the process can be strong and unpleasant. This is particularly the case when elasmobranch fish such as sharks and rays, are being salted and sun dried. A strong smell of ammonia produced by the fish will pervade the surrounding area making living conditions almost unbearable. It is important, therefore, that fish curing yards be sited away from urban areas or at least down-wind of them so that nuisance is kept to a minimum.