8 roads with worst air, and most not monitored
Researchers have singled out eight urban roads - most of which are not monitored by the government's air-quality network - as Hong Kong's most polluted thoroughfares.
The roads have nitrogen dioxide readings of up to 300 micrograms per cubic metre of air, categorised as 'very high' on the government scale.
Professors from the University of Science and Technology, in a study sponsored by the Jockey Club and supported by the think tank Civic Exchange, also found the eight roads far dirtier than two highways with far more traffic but better ventilation.
The information - released as the Environmental Protection Department is due to report progress of a review of air quality objectives to lawmakers on Monday - was collected with a mobile system the researchers and think tank said should be added to the network of fixed sites.
Using a specially equipped van, the team travelled through busy roads of all 18 districts from September last year to April. It spent four days on each district and measured each chosen road at least eight times, during and outside rush hours, to get an average.
They found high roadside pollution levels were not restricted to Central, Mong Kok and Causeway Bay, which the department monitors with fixed stations, but also existed in Kwun Tong, Hung Hom, Wan Chai, Kwai Chung and Eastern district.
Concentrations of nitrogen dioxide exceeded 300 on King's Road and Ma Tau Wai Road, which are not officially monitored, as well as Hennessy Road, Des Voeux Road Central and Nathan Road, parts of which are covered by the department's network.
And although Gloucester Road, Kwun Tong Road and Container Port Road South fared better, levels all exceeded 200, the more stringent target used by the World Health Organisation. All eight roads were more polluted than the more heavily used but better ventilated Tolo Highway and Kwun Tong Bypass.
The mobile monitor also found air quality varied dramatically within short distances, said Chan Chak-keung, director of the Institute for the Environment at the University of Science and Technology, who led the research. For example, the pollutant's level on Gloucester and Hennessy roads dropped from over 300 to 75 as they reached Victoria Park.
'Although it doesn't carry the heaviest traffic, the many high-rise buildings, buses, bus stops and traffic lights along Hennessy Road trap pollutants, making the corridor the dirtiest of all,' Chan said. 'More bus stops along the road means convenience, but there is a trade-off between air quality and convenience. We should look into the health risks.'
As the van measured air at a height of 3.5 metres, 'what we actually breathe in should be even worse', he said.
In the case of Container Port Road South, sulphur dioxide emissions from container ships at the Kwai Chung port were spread by southwesterly winds to the more uphill and less busy Lai King Hill Road during one-third of the measured time.
He urged the government to exercise more traffic control on busy routes, create more urban open space and control marine emissions by requiring ships to use cleaner fuel.
Erica Chan Fong-ying, of the Clean Air Network, said the study showed the three low-emission zones a government consultant proposed last year for Central, Causeway Bay and Mong Kok were too small. The Central zone missed Bonham Road and Garden Road, and the Mong Kok zone did not cover Yau Ma Tei and Jordan - places with schools, hospitals and health rehabilitation centres, where children and patients were concentrated, Chan said.
Civic Exchange chief executive Christine Loh Kung-wai said the government should add the mobile monitor to its fixed-point network.
The department said it would examine the team's data carefully. The siting of its roadside stations was in line with international practice, it said, and its measurements could not be compared with the team's because of different methodologies.