Reporter 445, 24 January 1999
Air pollution kills up to 24,000 people in the UK each year and traffic is one of the major sources of many of the chemicals blamed. In the widest-ranging study of urban pollution ever launched, University researchers are mapping the journey poisons make from pistons to people
Professor Gordon Andrews can test emissions making their way inside cars (above) and is developing engine components such as oil filters (below) which reduce emissions
The link between car exhausts and ill health is a difficult one to investigate as emissions quickly mix into the chemical soup that makes up our air. Traffic is known to contribute (up to 90% of nitrogen oxides in city air, for example, can be traced to its fumes) but greater efforts are being made to understand the link between cars, lorries and health.
New and ‘clean’ engines could even make the situation worse by producing particles so small they slip past the nostril hairs into the lungs.
Leeds’ Wellington Road was named as one of Britain’s most polluted roads in a pollution standards report published last year and many cities are struggling to meet strict air quality targets laid down by the government. To help them meet these requirements, and to make our urban environment more pleasant, Dr Margaret Bell, of the Institute for Transport Studies, is co-ordinating an inter-disciplinary project to investigate just how much damage our car-culture is causing.
The £4.2m award from the Joint Infrastructure Fund will equip a multidisciplinary team across six departments with the necessary tools to identify toxins released from vehicles, follow them through the air and trace them to the blood of drivers and pedestrians.
"The approach we are taking will answer many questions about possible ways forward," said Dr Bell. "For example, the government is encouraging car-drivers to park and ride into cities. Current data on pollution produced by petrol cars and diesel buses, however, is difficult to compare so we cannot accurately judge which is better for passengers and nearby pedestrians."
The pollutants spewed from exhausts include carbon monoxide and nitrogen oxides. Dr Bell believes the tests currently used to measure these chemicals are insufficient.
"Emissions measurements are taken from an idling engine or as a total produced during a ‘typical journey’. They do not take into account acceleration, braking or driving at speed, which all produce different amounts of the two pollutants," she said. "For example, traffic planners often try to keep cars moving to reduce carbon monoxide but this actually increases nitrogen oxides."
Professor Gordon Andrews in the fuel and energy department and Dr Girish Kale in mining and mineral engineering are developing emission-monitoring equipment that can be fitted to a car exhaust. Analysing fumes produced throughout the different stages of a typical journey will help determine how traffic management can reduce the most harmful effects.
Siting a set of traffic lights at the top and bottom of a hill, for example, produces different amounts of harsh acceleration, which leads to different emissions, said Dr Bell. The sensors will even be sensitive enough to compare different driving styles – from aggressive ‘boy racers’ to more sedate road users.
Once released from the exhaust the pollutants are dispersed and become more difficult to pinpoint. Roadside measurements help build up a picture of how the pollution fluctuates over time but are at the mercy of the weather, chemical changes and even, in one case, the fumes from a Chinese restaurant in Leicester.
Better results about the fate of pollutants in the atmosphere will be obtained using a mobile laboratory developed by Dr Paul Seakins in chemistry.
Comparing the measurements taken from the exhaust, with those of the surrounding atmosphere at different locations, will show where – and how quickly – noxious emissions are dispersed. The mass of data produced will be logged into manageable chunks with a new computer system prepared by Dr Alastair Watson in civil engineering.
The final piece in the jigsaw, and the ultimate destination of the chemicals produced by cars, lorries and buses, is the human body. The particulate dust produced by diesel engines is a particular hazard for the lungs. Belching buses are a common site but newer and ‘cleaner burning’ diesel engines may be a bigger problem as they produce smaller particles which slip past the nostril hairs into the lungs, said Dr Bell.
Other pollutants are broken down inside the body and Professor Chris Wild is leading research in the molecular epidemiology department to develop revolutionary biomarkers. These will pick out telltale residues in blood and urine.
"Children being taken to school by car encounter higher levels of pollution than those walking along the same street, but for a shorter time," said Dr Bell. "We will be able to determine which is worse for them by seeing which chemicals end up inside their bodies."
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