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Improving pollution monitoring in big cities

Air pollution in big cities across Asia is a major health issue and so monitoring pollution and its effect on people living in those areas is of huge importance. Researchers at King’s have now proposed new ways to monitor traffic related pollution that could give us a more accurate view of the impact that pollution is having on society and public health.

Many of the world’s megacities that have the most severe air pollution problems are cities in which a large number of people live in tall, densely clustered buildings. These clusters of high buildings are known to create ‘street canyons’ where air pollutants are trapped between buildings, increasing the levels of potentially harmful particles and gases found in the air.

Despite this, air pollution caused by traffic is currently monitored at ground level and calculations don’t account for the effects of these tall buildings. Many studies also don’t take into account mobility of residents orhow much exposure they experience every day as they move around their city.

Dr Ben Barratt and colleagues set out to monitor traffic-related air pollution (TRAP) in Hong Kong, not just across landscapes at ground level but by also monitoring upwards.

The team first mapped pollution levels at street level, by establishing a network of 100 monitors across Hong Kong. They then set up monitors inside and outside the homes of residents of six street canyons who lived at increasing heights above the street and sampled air continuously for four weeks – two weeks in the warm season and two in the cool season. They combined these data with information about movements of residents using travel behaviour surveys.

They found that looking at the data together in this way allowed them to see stronger links between air pollution and cardiovascular, respiratory and natural cause related deaths in a cohort of elderly Hong Kong residents.

Ben Barratt, says: ‘By looking at movements of pollutants in 3D you can uncover more detailed information about the impact of pollutants on health. We found significant associations between mortality and pollutant exposures that would not have been found by simply looking at the spread of pollutants at ground level.

‘Our study has shown that this type of advanced modelling is possible without an excess burden on resources and recommend that vertical movement of pollution should be incorporated in to future studies on the impact of pollution in cities like Hong Kong.’