BBC News, Hong Kong
Local air quality objectives are less stringent than WHO guidelines
Disappointment was the overriding emotion on the Tsim Sha Tsui waterfront.
"I can't really see anything," said one tourist peering into the amber haze.
What they were meant to see was the picture postcard view of Hong Kong's dramatic skyline. What they saw instead were some dark shapes across a body of water.
The literal translation of Hong Kong is "fragrant harbour", but lingering exhaust fumes leave more of an impression on the nose than any cool sea breeze.
A few businesses have already left for the sweeter air of Singapore.
Michael Short lived in Hong Kong for 17 years and he loved it. But in the 1990s things began to change.
"I'd go across the harbour on a daily basis and gradually realised things were getting worse. It became very depressing not to be able to see the other side," he said.
Mr Short is a company director, and 18 months ago he packed up and moved to Singapore.
"We could be doing this in Hong Kong, but none of the directors want to live there. That's the cold hard fact."
There are two main sources of air pollution in Hong Kong.
In terms of sheer tonnage, most of the air pollution comes from factories in the Pearl River Delta across the border, and it is the particulates they emit that cause the haze. But this comes in concentrated spurts.
The rest of the time it is local sources - vehicle emissions, power plants and marine traffic - that are at the root of the problem.
Christine Loh, head of the think tank Civic Exchange, says this means that blame cannot just be shifted over the border, and that the government has been slow to act.
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"So far, the government is in denial. It's not that the government is not doing anything. It's a question of whether it is doing enough, fast enough," she said.
Even the pollutants that drift over the border are in one sense "made in Hong Kong" - many of the 70,000 factories in the Pear River Delta are owned by Hong Kong businesses.
"Pollution is responsible for serious chronic disease and premature death on a daily basis," said Anthony Hedley, professor of community health at the University of Hong Kong.
He is less worried about departing expats than the children who grow up here.
Hong Kong's air quality objectives are 20 years old and less stringent than World Health Organisation guidelines set in 2006.
The government has commissioned its own review of objectives - but it has been accused of procrastination.
"It seems they want to postpone raising the objectives because of fear about Hong Kong's public image," said Bill Barron, an environmental economist at the Hong Kong University of Science and Technology.
In the choked-up district of Causeway Bay, Annelise Connell and Phil Heung of environmental group Clear the Air don fluorescent vests and patrol the streets, confronting the drivers of vehicles with idling engines.
"You get up in the morning and the government says that pollution is going to be high today - what a way to live!" said Ms Connell.
The Environmental Protection Department has put in measures such as tightening vehicle emission standards, introducing cleaner fuels and controlling smoky engines.
Such policies have succeeded, in that overall pollutant emissions from road vehicles have dropped sharply since 1997.
But this has not significantly lowered levels of air pollution at the roadside itself, which remain very high. This is in a city where almost half the population lives five minutes away from heavy traffic.
Part of the problem lies in the very structure of such a densely populated place as Hong Kong, where congested roads and high-rise buildings prevent pollutants from being dispersed by wind.
Then there is the structure of policy-making.
The Environmental Protection Department (EPD) acknowledged the impact of air pollution in a statement: "Eliminating environmental pollution has a significant bearing not only on public health and the quality of life, but also on the long-term development of Hong Kong."
But campaigners argue that Hong Kong's legislature is heavily tilted towards business, in particular the transport lobby.
Roadside air pollution remains high, despite restrictions
One of the "functional constituency" seats ( legislative council seats reserved for special interest groups) is elected by the transport sector.
"It's very much pro-roads," said Dr Barron. "The two rail companies have one vote each, and the taxi owners and mini bus owners have many votes.
"It's not based on how big a share of the transport you hold but how many companies there are."
Miriam Lau, the representative of the transport functional constituency, insisted that industry was co-operating.
"Environmentalists want change overnight. But this is a business society. If companies have made investments, they cannot simply throw it all away. Time is needed to make changes," she said.
She argued that the public - through their directly elected representatives - are as eager to keep road transport options open as any transport lobbyist.
There are positive signs of cross-border co-operation between Hong Kong and Guangdong. A joint air quality monitoring mechanism has been set up and both governments have committed to reducing emissions of certain pollutants by 2010.
The voluntary Clean Air Charter launched by the Hong Kong General Chambers of Commerce and the Business Council on the Environment makes certain green requirements of businesses.
The largest employer in Hong Kong, the government, has already signed up.
There are also more plans to reduce power plant and vehicle emissions.
Michael Short said he would return to Hong Kong if the skies cleared up.
Time will tell if the government's initiatives meet his challenge.