The Hong Kong Observatory's director said it could have released a day earlier test results showing that radioactive iodine had descended on the city from the damaged Japanese nuclear power station since Saturday, but had held back to verify.
Dr Lee Boon-ying, the Observatory chief, said yesterday that caution was needed for better accuracy of data and to avoid unnecessary public speculation about possible health threats, even though the level detected was extremely low.
The results announcement was made on Tuesday, three days after the radioactive dust was detected.
'We considered whether to release the findings to the public [on Monday] but our decision was to hold them until we had finished another measurement to verify the results,' Lee said yesterday.
'We could not tell the public on Monday that we might have detected it as it could have led to more speculation and even some chaos.'
Lee retires next month after working at the Observatory for 31 years.
The latest readings showed that the iodine level had gone up 56 per cent from the level measured in air samples taken between Sunday and Monday, but was still negligible, the Observatory said.