There has been a great deal of information in the trade press and television recently about swimming pools and the problem associate with trichloramines acting as a precursor for asthma. Certainly if you go into a swimming pool and your eyes sting from the trichloramine, it also means that there is damage being done to your lungs, the difference is that you don’t feel your lungs sting.

Duty of Care
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The swimming pool and spa industry has a Duty of Care for their clients. If you know that you are causing health issues then you should be taking action to resolve the problem. The public and pool staff are becoming more aware of the health implications of swimming and working in these environments, it is only a matter of time before there are litigation cases against swimming pool operators that are not practicing a “Duty of Care”. It is unfortunate that we have these problems because swimming is one of the best exercise activities for health and fitness.

Over the last 10 years there has been a huge amount of research concentrating on the health effects of trichloramines, and as a consequence the maximum permissible trichloramine level has been reduced in several European Countries. Germany is one notable example with a limit of 10ppb, in the UK the limit is 100ppb however the maximum concentration is not enforced. Indeed the trichloramine levels are very rarely even monitored.

I consider the parallel with trichloramines to be almost similar the series of events that took place with asbestos. We have known about the problem for decades but nothing was actually done for around 40 years, in the intervening time the public suffered.

The research to date has centered on the public health effects of trichloramine, but very little has been accomplished in finding out how trichloramines are produced in swimming pools. It is only once you know the mechanism that you can actually do something about solving the problem. This seems a logical first step, but it is a first step that has never been taken. Dryden Aqua has recently completed a 3 year research project funded by the European Commission under the
Life Environment initiative. The research concentrated on water filtration, but as opposed to focusing on a narrow field, the research was expanded to encompass not only the physical effects of filtration but also the chemical and biological interactions. It was discovered that trichloramines are produced by a reaction between ammonium and chlorine in the thin bacteria film called the biofilm that coats every surface in contact with the water.

The largest single surface in contact with the water is the sand in the sand filters. One tonne of sand has a surface area in the order of 3000 square meters. Since it is impossible to prevent bacteria growing on sand, the sand filters become the largest point source of trichloramine. Good equipment and system management can improve the situation, but they can not prevent trichloramine production. Given that the sand is the source of trichloramine, the solution to the problem is simple, you eliminate the sand.

The European Commission research conducted by Dryden Aqua resulted in the development of AFM (Active Filter Media), details from www.AFM.eu . AFM media replaces the sand in sand filters, and because AFM does not support bacterial growth, there is no biofilm and no trichloramine production. A small amount of trichloramine will still be produced by biofilm on the surfaces of the tiles, pipes and solids removed by the AFM media, however the largest single point source of trichloramines has now been eliminated.

The solution is simple; change the sand in your filters to AFM media.