Two Hong Kong-funded air pollution studies in the Pearl River Delta region have not been fully disclosed to the public because Guangdong authorities object to releasing "confidential information" in them, the Hong Kong government has admitted.
The 2½ projects were commissioned in 2007 to study the formation of photochemical smog, or ozone pollution, and industrial sources of air pollution in the region.
Costing HK$10 million each, both studies were completed and filed to the commissioning body, the Environmental Protection Department, in June 2011.
But it was only in May this year that the department quietly uploaded the summary reports, of 11 and 15 pages, to its website.
The reports provided the scientific basis for setting new cross-border targets in emission cuts for next year and 2020, and for enhancing an air-quality monitoring network, a department spokesman said.
But Hong Kong had a binding agreement with Guangdong not to release the reports, which contained unspecified sensitive information, he said.
"The two studies were conducted within the region, which contained confidential information collected in the economic zone of [the Pearl River Delta]. Our Guangdong counterparts considered it inappropriate to disclose such information."
He said the province's role in the studies was only providing back-up and technical support, including "professional input" on selecting sample sites.
The embargo decision was in stark contrast to the complete disclosure in 2002 of an unprecedented regional air-quality report, including its technical annexes.
That report formed the basis on which the first cross-border emission-reduction targets were set.
A spokesman for the Guangdong Environmental Protection Bureau insisted the embargo was necessary as the reports had "some data about some enterprises. We have made a simplified version of what the public needs to know about it."
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In Hong Kong, Democratic Party lawmaker Wu Chi-wai said there was no justification for holding back the reports, which were already three years old.
"Everything about the mainland is confidential or sensitive. If that's the case, we won't be able to achieve anything on anything involving the mainland," he said.
Wu said that without the full report, it would be difficult to monitor whether the government had made the right policy decisions or measures.
Green Power chief executive Dr Man Chi-sum said Hong Kong and Guangdong might be overreacting about the reports.
"We are not talking about emissions from a particular power plant that we want to hold responsible," he said. "We want more about the trends."
Man noted that as the mainland stepped up its fight against pollution, many cities that once saw air-quality data as highly confidential were now willing to reveal their monitoring data, even on a real-time basis.
The ozone study involved collecting samples of volatile organic compounds (VOCs) at 84 locations in the delta region via eight measurements from September 2008 to December 2009.
VOCs constitute a smog-inducing pollutant that reacts with nitrogen dioxides in the air to form ozone.
In the other study, on industrial pollution sources, data was gathered from more than 150 selected enterprises about their production, operational processes and airborne emissions.