An air-purification unit the size of a bus shelter could help reduce dangerous pollution in large cities

Air-purification unit for cities cuts pollution by 40 per cent

An air-purification unit the size of a bus shelter designed to remove dangerous pollutants from the atmosphere of busy cities has been tested in Hong Kong.

Developed jointly by London-headquartered built environment consultancy Arup and Hong Kong-based property developer Sino Group, the technology has contributed to a ‘significant improvement in air quality’ during the two-week trial, the firms said.

“We are glad that the empirical data show encouraging results with significant improvement in concentration of pollutants,” said Jimmy Tong of Arup. “Street Canyon Effect attributes to the accumulation of air pollutants on the street; meanwhile, the air purification system allows simultaneous production of air currents in between buildings and roads which generate wind channels to improve roadside ventilation in addition to purify air through filtration.”

The prototype has been set up at Hong Kong’s Queen’s Road East, one of the busiest streets in the city.

The filtration unit, awaiting a patent, draws air in through an inlet located at the bottom. The air is sucked through a bag filter which removes fine particles. It can effectively remove even the smallest particles less than 10 micrometres in diameter, also known as PM10 and PM2.5. These particles are particularly dangerous as they are usually not filtered out by the human respiratory system and can accumulate in the lungs.

Particles smaller than 2.5 micrometres, only detectable by electron microscopes, are a common by-product of combustion processes. Cars, power plants as well as wood burning  and forest fires are a frequent source of PM2.5s.

In the tests, the Arup and Sino Group system reduced concentrations of such pollutants on avarage by 40 per cent.

“We hope this green initiative brings real benefits to our society, and also inspires more people to contribute to a greener future,” said David Ng, Executive Assistant to Chairman of the Sino Group.

“Hong Kong is a densely populated city with busy road traffic, and poor roadside air quality poses a threat to public health. The technology is a welcome development, which has wide applications, including existing canopy structures of buildings in addition to transport network.”

The two firms envision the system could be used in other bus shelters or tram stations to improve air quality in Hong Kong but are also hoping China, battling excessive pollution, will find the invention attractive. 

The prototype is collecting data in real time, sharing them via a Hong Kong air-quality website.

The system will be installed at other locations with Arup and the Sino Group already considering enhancements, including installation of smart-controllers to control operating hours, solar panels to harvest solar energy, energy tiles for generating energy through stepping onto the tiles and a mist cooling system for cooling in hot weather.

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