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Grading of beach water quality
The Environmental Protection Department (EPD) today (Thursday) announced the latest grading of Hong Kong's beaches, based on the bacteriological water quality.
The purpose of the grading system is to inform swimmers and the general public about the state of bacteriological pollution at various beaches.
The grading will be announced bi-weekly during the bathing season to coincide with the frequency at which beach waters are usually sampled.
The grading is based on the most recent data obtained by the department in its routine monitoring programme.
It gives an estimate on the risk of contracting some minor skin or gastrointestinal illnesses resulted from swimming at a beach with some degree of pollution.
The estimate is based on a large scale epidemiological study carried out in Hong Kong in the past bathing seasons.
The grading of some beaches fluctuates during the summer. In most cases, this represents a natural fluctuation in the bacteriological quality of bathing waters as rain and tides bring more or less pollution to the beaches.
Beaches with highly developed hinterlands are likely to be more polluted than the grades suggested during and after heavy rain.
Principal Environmental Protection Officer Dr Daniel Lau said: "Bathers should avoid swimming at such beaches for two to three days after a storm, or even longer if the weather remains overcast, shorter if there is strong sunshine."
However, the bi-weekly grades give a general picture of the most recent water quality at bathing beaches at the time of reporting and form the best available forecast for the immediate future.
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.