XN000022-1996-04-25 — Page 13

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The grading will be announced biweekly during the bathing season to coincide with the frequency at which beach waters are usually sampled.

The grading is based on the most recent E coli data obtained by the EPD in its routine monitoring programme.

As with last year, the grading also includes an estimate of the risk of contracting some minor skin or gastrointestinal complaints as a result of swimming at a beach which has some degree of pollution.

The estimate is based on a very large body of statistical information gathered in Hong Kong in recent bathing seasons.

The grading of some beaches may vary during the summer. This represents a natural fluctuation in the bacteriological quality of bathing waters in most cases, as rain and tides bring more or less pollution to the beaches.

However, the grades give a good general picture of the water quality at bathing beaches at the time of reporting and form the best available forecast for the immediate future.

Beaches with highly developed hinterlands are likely to be more polluted than the grades suggest during and after heavy rain.

"Bathers should avoid such beaches for two or three days after a storm, longer if the weather remains overcast or less if there is strong sunshine", acting Principal Environmental Protection Officer, Mr Edmond Ho, said.

The system for grading beach water quality is as follows:

Grade "1" indicates that the water quality is good. The E coli count is no more than 24 per 100 millilitres at each beach so graded, and the expected risk of minor illness to swimmers is undetectable.

Grade "2" indicates that the water quality is fair. The E coli count is no more than 180 per 100 millilitres at each beach so graded, and the expected health risk is no more than 10 cases of minor illness per 1,000 swimmers.

Grade "3" indicates that the water quality is poor. The E coli count is no more than 610 per 100 millilitres at each beach so graded, and the expected health risk is no more than 15 cases of minor illness per 1,000 swimmers.